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Lu, Huayi a24ca60074 DWS DEVELOPER 811 version 
Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2023-01-19 13:37:49 +00:00

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<a name="EN-US_TOPIC_0000001145830495"></a><a name="EN-US_TOPIC_0000001145830495"></a>
<h1 class="topictitle1">HLL Functions and Operators</h1>
<div id="body1551855680017"><div class="section" id="EN-US_TOPIC_0000001145830495__section432010211209"><h4 class="sectiontitle">Hash Functions</h4><ul id="EN-US_TOPIC_0000001145830495__ul044442754013"><li id="EN-US_TOPIC_0000001145830495__li044432719402">hll_hash_boolean(bool)<p id="EN-US_TOPIC_0000001145830495__p11671938194011"><a name="EN-US_TOPIC_0000001145830495__li044432719402"></a><a name="li044432719402"></a>Description: Hashes data of the bool type.</p>
<p id="EN-US_TOPIC_0000001145830495__p389216367402">Return type: hll_hashval</p>
<div class="p" id="EN-US_TOPIC_0000001145830495__p10161636154017">For example:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen939894763819"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_boolean</span><span class="p">(</span><span class="k">FALSE</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_boolean</span><span class="w"> </span>
<span class="c1">---------------------</span>
<span class="w"> </span><span class="mi">5048724184180415669</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</div>
</li></ul>
</div>
<ul id="EN-US_TOPIC_0000001145830495__ul985122220374"><li id="EN-US_TOPIC_0000001145830495__li19663103853914">hll_hash_boolean(bool, int32)<p id="EN-US_TOPIC_0000001145830495__p1352075519394"><a name="EN-US_TOPIC_0000001145830495__li19663103853914"></a><a name="li19663103853914"></a>Description: Configures a hash seed (that is, change the hash policy) and hashes data of the bool type.</p>
<p id="EN-US_TOPIC_0000001145830495__p17521125513910">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p452195517393">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen24323116480"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_boolean</span><span class="p">(</span><span class="k">FALSE</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_boolean</span><span class="w"> </span>
<span class="c1">--------------------</span>
<span class="w"> </span><span class="mi">391264977436098630</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li14867105411381">hll_hash_smallint(smallint)<p id="EN-US_TOPIC_0000001145830495__p292921017397"><a name="EN-US_TOPIC_0000001145830495__li14867105411381"></a><a name="li14867105411381"></a>Description: Hashes data of the smallint type.</p>
<p id="EN-US_TOPIC_0000001145830495__p184757292394">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p12886274013">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen162251923194017"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_smallint</span><span class="p">(</span><span class="mi">100</span><span class="p">::</span><span class="nb">smallint</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_smallint</span><span class="w"> </span>
<span class="c1">---------------------</span>
<span class="w"> </span><span class="mi">4631120266694327276</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
<div class="note" id="EN-US_TOPIC_0000001145830495__note79339532436"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001145830495__p124422034154116">If parameters with the same numeric value are hashed using different data types, the data will differ, because hash functions select different calculation policies for each type.</p>
</div></div>
<ul id="EN-US_TOPIC_0000001145830495__ul13560111124510"><li id="EN-US_TOPIC_0000001145830495__li146341704447">hll_hash_smallint(smallint, int32)<p id="EN-US_TOPIC_0000001145830495__p9773181514442"><a name="EN-US_TOPIC_0000001145830495__li146341704447"></a><a name="li146341704447"></a>Description: Configures a hash seed (that is, change the hash policy) and hashes data of the smallint type.</p>
<p id="EN-US_TOPIC_0000001145830495__p20773315124414">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p4773171544410">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen67311258194920"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_smallint</span><span class="p">(</span><span class="mi">100</span><span class="p">::</span><span class="nb">smallint</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_smallint</span><span class="w"> </span>
<span class="c1">---------------------</span>
<span class="w"> </span><span class="mi">8349353095166695771</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1956018174510">hll_hash_integer(integer)<p id="EN-US_TOPIC_0000001145830495__p188441026174510"><a name="EN-US_TOPIC_0000001145830495__li1956018174510"></a><a name="li1956018174510"></a>Description: Hashes data of the integer type.</p>
<p id="EN-US_TOPIC_0000001145830495__p9109154417457">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p77875718452">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen19719151604620"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">0</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_integer</span><span class="w"> </span>
<span class="c1">----------------------</span>
<span class="w"> </span><span class="o">-</span><span class="mi">3485513579396041028</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li10559161815111">hll_hash_integer(integer, int32)<p id="EN-US_TOPIC_0000001145830495__p10177323145115"><a name="EN-US_TOPIC_0000001145830495__li10559161815111"></a><a name="li10559161815111"></a>Description: Hashes data of the integer type and configures a hash seed (that is, change the hash policy).</p>
<p id="EN-US_TOPIC_0000001145830495__p717712310518">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p19177102375115">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen86051114205619"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="w"> </span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_integer</span><span class="w"> </span>
<span class="c1">--------------------</span>
<span class="w"> </span><span class="mi">183371090322255134</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li690632444615">hll_hash_bigint(bigint)<p id="EN-US_TOPIC_0000001145830495__p1824419483"><a name="EN-US_TOPIC_0000001145830495__li690632444615"></a><a name="li690632444615"></a>Description: Hashes data of the bigint type.</p>
<p id="EN-US_TOPIC_0000001145830495__p11598191915488">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p1497803104816">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen936855417488"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_bigint</span><span class="p">(</span><span class="mi">100</span><span class="p">::</span><span class="nb">bigint</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_bigint</span><span class="w"> </span>
<span class="c1">---------------------</span>
<span class="w"> </span><span class="mi">8349353095166695771</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li175361985218">hll_hash_bigint(bigint, int32)<p id="EN-US_TOPIC_0000001145830495__p01736302526"><a name="EN-US_TOPIC_0000001145830495__li175361985218"></a><a name="li175361985218"></a>Description: Hashes data of the bigint type and configures a hash seed (that is, change the hash policy).</p>
<p id="EN-US_TOPIC_0000001145830495__p817373015525">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p16173530175215">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen201521340125618"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_bigint</span><span class="p">(</span><span class="mi">100</span><span class="p">::</span><span class="nb">bigint</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_bigint</span><span class="w"> </span>
<span class="c1">---------------------</span>
<span class="w"> </span><span class="mi">4631120266694327276</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1671222194916">hll_hash_bytea(bytea)<p id="EN-US_TOPIC_0000001145830495__p1390229154916"><a name="EN-US_TOPIC_0000001145830495__li1671222194916"></a><a name="li1671222194916"></a>Description: Hashes data of the bytea type.</p>
<p id="EN-US_TOPIC_0000001145830495__p1488716439493">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p15816142145212">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen14291944185213"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_bytea</span><span class="p">(</span><span class="n">E</span><span class="s1">'\\x'</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_bytea</span><span class="w"> </span>
<span class="c1">----------------</span>
<span class="w"> </span><span class="mi">0</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1138520117537">hll_hash_bytea(bytea, int32)<p id="EN-US_TOPIC_0000001145830495__p9474113115313"><a name="EN-US_TOPIC_0000001145830495__li1138520117537"></a><a name="li1138520117537"></a>Description: Hashes data of the bytea type and configures a hash seed (that is, change the hash policy).</p>
<p id="EN-US_TOPIC_0000001145830495__p164741913115317">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p17474181345310">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen14995846195613"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_bytea</span><span class="p">(</span><span class="n">E</span><span class="s1">'\\x'</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_bytea</span><span class="w"> </span>
<span class="c1">---------------------</span>
<span class="w"> </span><span class="mi">6574525721897061910</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1441418172539">hll_hash_text(text)<p id="EN-US_TOPIC_0000001145830495__p975971875412"><a name="EN-US_TOPIC_0000001145830495__li1441418172539"></a><a name="li1441418172539"></a>Description: Hashes data of the text type.</p>
<p id="EN-US_TOPIC_0000001145830495__p1356010357542">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p169201850195417">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen924813111555"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_text</span><span class="p">(</span><span class="s1">'AB'</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_text</span><span class="w"> </span>
<span class="c1">---------------------</span>
<span class="w"> </span><span class="mi">5365230931951287672</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li8693717115410">hll_hash_text(text, int32)<p id="EN-US_TOPIC_0000001145830495__p5759191875417"><a name="EN-US_TOPIC_0000001145830495__li8693717115410"></a><a name="li8693717115410"></a>Description: Hashes data of the text type and configures a hash seed (that is, change the hash policy).</p>
<p id="EN-US_TOPIC_0000001145830495__p1975961813546">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p117599187549">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen7471125093417"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hll_hash_text</span><span class="p">(</span><span class="s1">'AB'</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="n">hll_hash_text</span><span class="w"></span>
<span class="c1">---------------------</span>
<span class="mi">7680762839921155903</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1234171916555">hll_hash_any(anytype)<p id="EN-US_TOPIC_0000001145830495__p5937103516556"><a name="EN-US_TOPIC_0000001145830495__li1234171916555"></a><a name="li1234171916555"></a>Description: Hashes data of any type.</p>
<p id="EN-US_TOPIC_0000001145830495__p1484847125510">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p58671952597">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen16992812185916"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_hash_any</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_any</span><span class="w"> </span>
<span class="c1">----------------------</span>
<span class="w"> </span><span class="o">-</span><span class="mi">8604791237420463362</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
<span class="k">select</span><span class="w"> </span><span class="n">hll_hash_any</span><span class="p">(</span><span class="s1">'08:00:2b:01:02:03'</span><span class="p">::</span><span class="n">macaddr</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_any</span><span class="w"> </span>
<span class="c1">----------------------</span>
<span class="w"> </span><span class="o">-</span><span class="mi">4883882473551067169</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li15301518185519">hll_hash_any(anytype, int32)<p id="EN-US_TOPIC_0000001145830495__p11527182214554"><a name="EN-US_TOPIC_0000001145830495__li15301518185519"></a><a name="li15301518185519"></a>Description: Hashes data of any type and configures a hash seed (that is, change the hash policy).</p>
<p id="EN-US_TOPIC_0000001145830495__p1652718228557">Return type: hll_hashval</p>
<p id="EN-US_TOPIC_0000001145830495__p7527422135514">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen315816253573"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_hash_any</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hash_any</span><span class="w"> </span>
<span class="c1">----------------------</span>
<span class="w"> </span><span class="o">-</span><span class="mi">1478847531811254870</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li789114975914">hll_hashval_eq(hll_hashval, hll_hashval)<p id="EN-US_TOPIC_0000001145830495__p7498123719018"><a name="EN-US_TOPIC_0000001145830495__li789114975914"></a><a name="li789114975914"></a>Description: Compares two pieces of data of the hll_hashval type to check whether they are the same.</p>
<p id="EN-US_TOPIC_0000001145830495__p119982521903">Return type: bool</p>
<p id="EN-US_TOPIC_0000001145830495__p473220582000">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen184516181417"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_hashval_eq</span><span class="p">(</span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hashval_eq</span><span class="w"> </span>
<span class="c1">----------------</span>
<span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li8451142520112">hll_hashval_ne(hll_hashval, hll_hashval)<p id="EN-US_TOPIC_0000001145830495__p763471424"><a name="EN-US_TOPIC_0000001145830495__li8451142520112"></a><a name="li8451142520112"></a>Description: Compares two pieces of data of the hll_hashval type to check whether they are different.</p>
<p id="EN-US_TOPIC_0000001145830495__p497629825">Return type: bool</p>
<p id="EN-US_TOPIC_0000001145830495__p614410385211">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen73758524"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_hashval_ne</span><span class="p">(</span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_hashval_ne</span><span class="w"> </span>
<span class="c1">----------------</span>
<span class="w"> </span><span class="n">f</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
<div class="section" id="EN-US_TOPIC_0000001145830495__section1615145915110"><h4 class="sectiontitle">Precision Functions</h4><p id="EN-US_TOPIC_0000001145830495__p1459914424415">HLL supports <strong id="EN-US_TOPIC_0000001145830495__b2218125734413">explicit</strong>, <strong id="EN-US_TOPIC_0000001145830495__b1751514115457">sparse</strong>, and <strong id="EN-US_TOPIC_0000001145830495__b981244124515">full</strong> modes. <strong id="EN-US_TOPIC_0000001145830495__b3616848103513">explicit</strong> and <strong id="EN-US_TOPIC_0000001145830495__b1661744818359">sparse</strong> excel when the data scale is small, and barely produce errors in calculation results. When the number of distinct values increases, <strong id="EN-US_TOPIC_0000001145830495__b153172525357">full</strong> becomes more suitable, but produces some errors. The following functions are used to view precision parameters in HLLs.</p>
</div>
<ul id="EN-US_TOPIC_0000001145830495__ul1536134010715"><li id="EN-US_TOPIC_0000001145830495__li103634012717">hll_schema_version(hll)<p id="EN-US_TOPIC_0000001145830495__p131926551716"><a name="EN-US_TOPIC_0000001145830495__li103634012717"></a><a name="li103634012717"></a>Description: Checks the schema version in the current HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p1764011597819">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen118593201792"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_schema_version</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_schema_version</span><span class="w"> </span>
<span class="c1">--------------------</span>
<span class="w"> </span><span class="mi">1</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li186561125291">hll_type(hll)<p id="EN-US_TOPIC_0000001145830495__p131220381690"><a name="EN-US_TOPIC_0000001145830495__li186561125291"></a><a name="li186561125291"></a>Description: Checks the type of the current HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p11497205914912">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen13543173010106"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_type</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_type</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="mi">1</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1176193861016">hll_log2m(hll)<p id="EN-US_TOPIC_0000001145830495__p8498143517260"><a name="EN-US_TOPIC_0000001145830495__li1176193861016"></a><a name="li1176193861016"></a>Description: Check the value of log2m of the current HLL. This value affects the error rate in calculating the number of distinct values by the HLL. The formula for calculating the error rate is as follows:</p>
<p id="EN-US_TOPIC_0000001145830495__p35854337613"><span><img id="EN-US_TOPIC_0000001145830495__image1568415491471" src="figure/en-us_image_0000001145830887.png"></span></p>
<p id="EN-US_TOPIC_0000001145830495__p894785514132">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen119003918144"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_log2m</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_log2m</span><span class="w"> </span>
<span class="c1">-----------</span>
<span class="w"> </span><span class="mi">11</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li16353516101417">hll_regwidth(hll)<p id="EN-US_TOPIC_0000001145830495__p154161231161410"><a name="EN-US_TOPIC_0000001145830495__li16353516101417"></a><a name="li16353516101417"></a>Description: Checks the number of bits of buckets in a hll data structure.</p>
<p id="EN-US_TOPIC_0000001145830495__p1693117529148">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen47445105156"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_regwidth</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_regwidth</span><span class="w"> </span>
<span class="c1">--------------</span>
<span class="w"> </span><span class="mi">5</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li283771671511">hll_expthresh(hll)<p id="EN-US_TOPIC_0000001145830495__p5745731101514"><a name="EN-US_TOPIC_0000001145830495__li283771671511"></a><a name="li283771671511"></a>Description: Obtains the size of <strong id="EN-US_TOPIC_0000001145830495__b181398303620">expthresh</strong> in the current HLL. An HLL usually switches from the <strong id="EN-US_TOPIC_0000001145830495__b11401034362">explicit</strong> mode to the <strong id="EN-US_TOPIC_0000001145830495__b1814103103612">sparse</strong> mode and then to the <strong id="EN-US_TOPIC_0000001145830495__b11411353616">full</strong> mode. This process is called the promotion hierarchy policy. You can change the value of <strong id="EN-US_TOPIC_0000001145830495__b1326464366">expthresh</strong> to change the policy. For example, if <strong id="EN-US_TOPIC_0000001145830495__b1632717663619">expthresh</strong> is <strong id="EN-US_TOPIC_0000001145830495__b632819616366">0</strong>, an HILL will skip the <strong id="EN-US_TOPIC_0000001145830495__b73286618369">explicit</strong> mode and directly enter the <strong id="EN-US_TOPIC_0000001145830495__b20329269366">sparse</strong> mode. If the value of <strong id="EN-US_TOPIC_0000001145830495__b19190154625318">expthresh</strong> is explicitly set to a value ranging from 1 to 7, this function returns 2<sup id="EN-US_TOPIC_0000001145830495__sup134945331612">expthresh</sup>.</p>
<p id="EN-US_TOPIC_0000001145830495__p1594874916153">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen14338910101614"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_expthresh</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_expthresh</span><span class="w"> </span>
<span class="c1">---------------</span>
<span class="w"> </span><span class="p">(</span><span class="o">-</span><span class="mi">1</span><span class="p">,</span><span class="mi">160</span><span class="p">)</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
<span class="k">select</span><span class="w"> </span><span class="n">hll_expthresh</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(</span><span class="mi">11</span><span class="p">,</span><span class="mi">5</span><span class="p">,</span><span class="mi">3</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_expthresh</span><span class="w"> </span>
<span class="c1">---------------</span>
<span class="w"> </span><span class="p">(</span><span class="mi">8</span><span class="p">,</span><span class="mi">8</span><span class="p">)</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1927621401615">hll_sparseon(hll)<p id="EN-US_TOPIC_0000001145830495__p19838823171611"><a name="EN-US_TOPIC_0000001145830495__li1927621401615"></a><a name="li1927621401615"></a>Description: Specifies whether to enable the <strong id="EN-US_TOPIC_0000001145830495__b19748112616565">sparse</strong> mode. <strong id="EN-US_TOPIC_0000001145830495__b175032625613">0</strong> indicates <strong id="EN-US_TOPIC_0000001145830495__b1875192625618">off</strong> and <strong id="EN-US_TOPIC_0000001145830495__b19751102635618">1</strong> indicates <strong id="EN-US_TOPIC_0000001145830495__b475220262560">on</strong>.</p>
<p id="EN-US_TOPIC_0000001145830495__p2071413457163">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen1380847151712"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_sparseon</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_sparseon</span><span class="w"> </span>
<span class="c1">--------------</span>
<span class="w"> </span><span class="mi">1</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
<div class="section" id="EN-US_TOPIC_0000001145830495__section52621914536"><h4 class="sectiontitle">Aggregation Functions</h4><ul id="EN-US_TOPIC_0000001145830495__ul184183451465"><li id="EN-US_TOPIC_0000001145830495__li338416476468">hll_add_agg(hll_hashval)<p id="EN-US_TOPIC_0000001145830495__p1847115251153"><a name="EN-US_TOPIC_0000001145830495__li338416476468"></a><a name="li338416476468"></a>Description: Groups hashed data into HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p1128415470158">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p08611252141511">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen7705135519166"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span>
<span class="normal">14</span>
<span class="normal">15</span>
<span class="normal">16</span>
<span class="normal">17</span>
<span class="normal">18</span>
<span class="normal">19</span></pre></div></td><td class="code"><div><pre><span></span><span class="c1">-- Prepare data:</span>
<span class="k">create</span><span class="w"> </span><span class="k">table</span><span class="w"> </span><span class="n">t_id</span><span class="p">(</span><span class="n">id</span><span class="w"> </span><span class="nb">int</span><span class="p">);</span><span class="w"></span>
<span class="k">insert</span><span class="w"> </span><span class="k">into</span><span class="w"> </span><span class="n">t_id</span><span class="w"> </span><span class="k">values</span><span class="p">(</span><span class="n">generate_series</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span><span class="mi">500</span><span class="p">));</span><span class="w"></span>
<span class="k">create</span><span class="w"> </span><span class="k">table</span><span class="w"> </span><span class="n">t_data</span><span class="p">(</span><span class="n">a</span><span class="w"> </span><span class="nb">int</span><span class="p">,</span><span class="w"> </span><span class="k">c</span><span class="w"> </span><span class="nb">text</span><span class="p">);</span><span class="w"></span>
<span class="k">insert</span><span class="w"> </span><span class="k">into</span><span class="w"> </span><span class="n">t_data</span><span class="w"> </span><span class="k">select</span><span class="w"> </span><span class="k">mod</span><span class="p">(</span><span class="n">id</span><span class="p">,</span><span class="mi">2</span><span class="p">),</span><span class="w"> </span><span class="n">id</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_id</span><span class="p">;</span><span class="w"></span>
<span class="c1">-- Create another table and specify an HLL column:</span>
<span class="k">create</span><span class="w"> </span><span class="k">table</span><span class="w"> </span><span class="n">t_a_c_hll</span><span class="p">(</span><span class="n">a</span><span class="w"> </span><span class="nb">int</span><span class="p">,</span><span class="w"> </span><span class="k">c</span><span class="w"> </span><span class="n">hll</span><span class="p">);</span><span class="w"></span>
<span class="c1">-- Use GROUP BY on column a to group data, and insert the data to the HLL:</span>
<span class="k">insert</span><span class="w"> </span><span class="k">into</span><span class="w"> </span><span class="n">t_a_c_hll</span><span class="w"> </span><span class="k">select</span><span class="w"> </span><span class="n">a</span><span class="p">,</span><span class="w"> </span><span class="n">hll_add_agg</span><span class="p">(</span><span class="n">hll_hash_text</span><span class="p">(</span><span class="k">c</span><span class="p">))</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_data</span><span class="w"> </span><span class="k">group</span><span class="w"> </span><span class="k">by</span><span class="w"> </span><span class="n">a</span><span class="p">;</span><span class="w"></span>
<span class="c1">-- Calculate the number of distinct values for each group in the HLL:</span>
<span class="k">select</span><span class="w"> </span><span class="n">a</span><span class="p">,</span><span class="w"> </span><span class="o">#</span><span class="k">c</span><span class="w"> </span><span class="k">as</span><span class="w"> </span><span class="k">cardinality</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_a_c_hll</span><span class="w"> </span><span class="k">order</span><span class="w"> </span><span class="k">by</span><span class="w"> </span><span class="n">a</span><span class="p">;</span><span class="w"></span>
<span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">cardinality</span><span class="w"> </span>
<span class="c1">---+------------------</span>
<span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">250</span><span class="p">.</span><span class="mi">741759091658</span><span class="w"></span>
<span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">250</span><span class="p">.</span><span class="mi">741759091658</span><span class="w"></span>
<span class="p">(</span><span class="mi">2</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</div>
<ul id="EN-US_TOPIC_0000001145830495__ul13721161131510"><li id="EN-US_TOPIC_0000001145830495__li1450517214596">hll_add_agg(hll_hashval, int32 log2m)<p id="EN-US_TOPIC_0000001145830495__p1987284112595"><a name="EN-US_TOPIC_0000001145830495__li1450517214596"></a><a name="li1450517214596"></a>Description: Groups hashed data into HLL and sets the <strong id="EN-US_TOPIC_0000001145830495__b1353841513415">log2m</strong> parameter. The parameter value ranges from 10 to 16.</p>
<p id="EN-US_TOPIC_0000001145830495__p6872204112591">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p1087204113597">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen1144945161113"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="w"> </span><span class="k">Select</span><span class="w"> </span><span class="n">hll_cardinality</span><span class="p">(</span><span class="n">hll_add_agg</span><span class="p">(</span><span class="n">hll_hash_text</span><span class="p">(</span><span class="k">c</span><span class="p">),</span><span class="w"> </span><span class="mi">10</span><span class="p">))</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_data</span><span class="p">;</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_cardinality</span><span class="w"> </span>
<span class="c1">------------------</span>
<span class="w"> </span><span class="mi">503</span><span class="p">.</span><span class="mi">932348927339</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li420241718318">hll_add_agg(hll_hashval, int32 log2m, int32 regwidth)<p id="EN-US_TOPIC_0000001145830495__p1423816181547"><a name="EN-US_TOPIC_0000001145830495__li420241718318"></a><a name="li420241718318"></a>Description: Groups hashed data into HLL and sets the <strong id="EN-US_TOPIC_0000001145830495__b1880893812520">log2m</strong> and <strong id="EN-US_TOPIC_0000001145830495__b179303418519">regwidth</strong> parameters in sequence. The value of <strong id="EN-US_TOPIC_0000001145830495__b470502669">regwidth</strong> ranges from 1 to 5.</p>
<p id="EN-US_TOPIC_0000001145830495__p1023881817415">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p122380181943">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen13205143014228"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">Select</span><span class="w"> </span><span class="n">hll_cardinality</span><span class="p">(</span><span class="n">hll_add_agg</span><span class="p">(</span><span class="n">hll_hash_text</span><span class="p">(</span><span class="k">c</span><span class="p">),</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">))</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_data</span><span class="p">;</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_cardinality</span><span class="w"> </span>
<span class="c1">------------------</span>
<span class="w"> </span><span class="mi">496</span><span class="p">.</span><span class="mi">628982624022</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li2021817135616">hll_add_agg(hll_hashval, int32 log2m, int32 regwidth, int64 expthresh)<p id="EN-US_TOPIC_0000001145830495__p1053925568"><a name="EN-US_TOPIC_0000001145830495__li2021817135616"></a><a name="li2021817135616"></a>Description: Groups hashed data into HLL and sets the parameters <strong id="EN-US_TOPIC_0000001145830495__b1844354818576">log2m</strong>, <strong id="EN-US_TOPIC_0000001145830495__b464725011575">regwidth</strong>, and <strong id="EN-US_TOPIC_0000001145830495__b174121356125719">expthresh</strong> in sequence. The value of <strong id="EN-US_TOPIC_0000001145830495__b10982132035812">expthresh</strong> is an integer ranging from –1 to 7. <strong id="EN-US_TOPIC_0000001145830495__b15417119838">expthresh</strong> is used to specify the threshold for switching from the <strong id="EN-US_TOPIC_0000001145830495__b8292133810318">explicit</strong> mode to the <strong id="EN-US_TOPIC_0000001145830495__b1052515471533">sparse</strong> mode. <strong id="EN-US_TOPIC_0000001145830495__b19867125919319">–1</strong> indicates the auto mode; <strong id="EN-US_TOPIC_0000001145830495__b642173315417">0</strong> indicates that the <strong id="EN-US_TOPIC_0000001145830495__b1945494910414">explicit</strong> mode is skipped; a value from 1 to 7 indicates that the mode is switched when the number of distinct values reaches 2<sup id="EN-US_TOPIC_0000001145830495__sup112656249195"><strong id="EN-US_TOPIC_0000001145830495__b208165184812">expthresh</strong></sup>.</p>
<p id="EN-US_TOPIC_0000001145830495__p13531025367">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p8534254610">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen99971539142319"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="w"> </span><span class="k">Select</span><span class="w"> </span><span class="n">hll_cardinality</span><span class="p">(</span><span class="n">hll_add_agg</span><span class="p">(</span><span class="n">hll_hash_text</span><span class="p">(</span><span class="k">c</span><span class="p">),</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">))</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_data</span><span class="p">;</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_cardinality</span><span class="w"> </span>
<span class="c1">------------------</span>
<span class="w"> </span><span class="mi">496</span><span class="p">.</span><span class="mi">628982624022</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li599851619816">hll_add_agg(hll_hashval, int32 log2m, int32 regwidth, int64 expthresh, int32 sparseon)<p id="EN-US_TOPIC_0000001145830495__p142701419188"><a name="EN-US_TOPIC_0000001145830495__li599851619816"></a><a name="li599851619816"></a>Description: Groups hashed data into HLL and sets the <strong id="EN-US_TOPIC_0000001145830495__b811474016810">log2m</strong>, <strong id="EN-US_TOPIC_0000001145830495__b6360114111811">regwidth</strong>, <strong id="EN-US_TOPIC_0000001145830495__b127044516815">expthresh</strong>, and <strong id="EN-US_TOPIC_0000001145830495__b662744811814">sparseon</strong> parameters in sequence. The value of <strong id="EN-US_TOPIC_0000001145830495__b3462197131415">sparseon</strong> is <strong id="EN-US_TOPIC_0000001145830495__b59371822911">0</strong> or <strong id="EN-US_TOPIC_0000001145830495__b84781461798">1</strong>.</p>
<p id="EN-US_TOPIC_0000001145830495__p102701919181">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p1027014194811">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen4897191820299"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="w"> </span><span class="k">Select</span><span class="w"> </span><span class="n">hll_cardinality</span><span class="p">(</span><span class="n">hll_add_agg</span><span class="p">(</span><span class="n">hll_hash_text</span><span class="p">(</span><span class="k">c</span><span class="p">),</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span><span class="w"> </span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">))</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_data</span><span class="p">;</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_cardinality</span><span class="w"> </span>
<span class="c1">------------------</span>
<span class="w"> </span><span class="mi">496</span><span class="p">.</span><span class="mi">628982624022</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li149714387173">hll_union_agg(hll)<p id="EN-US_TOPIC_0000001145830495__p1619444182"><a name="EN-US_TOPIC_0000001145830495__li149714387173"></a><a name="li149714387173"></a>Description: Perform the <strong id="EN-US_TOPIC_0000001145830495__b181714176359">UNION</strong> operation on multiple pieces of data of the hll type to obtain one HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p8894142313186">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p7206133211186">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen1668214125305"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span></pre></div></td><td class="code"><div><pre><span></span><span class="c1">-- Perform the UNION operation on data of the hll type in each group to obtain one HLL, and calculate the number of distinct values:</span>
<span class="k">select</span><span class="w"> </span><span class="o">#</span><span class="n">hll_union_agg</span><span class="p">(</span><span class="k">c</span><span class="p">)</span><span class="w"> </span><span class="k">as</span><span class="w"> </span><span class="k">cardinality</span><span class="w"> </span><span class="k">from</span><span class="w"> </span><span class="n">t_a_c_hll</span><span class="p">;</span><span class="w"></span>
<span class="w"> </span><span class="k">cardinality</span><span class="w"> </span>
<span class="c1">------------------</span>
<span class="w"> </span><span class="mi">496</span><span class="p">.</span><span class="mi">628982624022</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
<div class="note" id="EN-US_TOPIC_0000001145830495__note42005853413"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001145830495__p02075810346">To perform <strong id="EN-US_TOPIC_0000001145830495__b014718258118">UNION</strong> on data in multiple HLLs, ensure that the HLLs have the same precision. Otherwise, <strong id="EN-US_TOPIC_0000001145830495__b11295354124">UNION</strong> cannot be performed. This restriction also applies to the hll_union(hll, hll) function.</p>
</div></div>
</li></ul>
<div class="section" id="EN-US_TOPIC_0000001145830495__section17355134113311"><h4 class="sectiontitle">Functional Functions</h4><ul id="EN-US_TOPIC_0000001145830495__ul19311914134811"><li id="EN-US_TOPIC_0000001145830495__li1918101619482">hll_print(hll)<p id="EN-US_TOPIC_0000001145830495__p1167654218200"><a name="EN-US_TOPIC_0000001145830495__li1918101619482"></a><a name="li1918101619482"></a>Description: Prints some debugging parameters of an HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p15725115513207">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen533419108215"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_print</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_print</span><span class="w"> </span>
<span class="c1">-----------------------------------------------------------</span>
<span class="w"> </span><span class="n">EMPTY</span><span class="p">,</span><span class="w"> </span><span class="n">nregs</span><span class="o">=</span><span class="mi">2048</span><span class="p">,</span><span class="w"> </span><span class="n">nbits</span><span class="o">=</span><span class="mi">5</span><span class="p">,</span><span class="w"> </span><span class="n">expthresh</span><span class="o">=-</span><span class="mi">1</span><span class="p">(</span><span class="mi">160</span><span class="p">),</span><span class="w"> </span><span class="n">sparseon</span><span class="o">=</span><span class="mi">1</span><span class="n">gongne</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</div>
<ul id="EN-US_TOPIC_0000001145830495__ul192613016208"><li id="EN-US_TOPIC_0000001145830495__li6147111818213">hll_empty()<p id="EN-US_TOPIC_0000001145830495__p1639774632111"><a name="EN-US_TOPIC_0000001145830495__li6147111818213"></a><a name="li6147111818213"></a>Description: Creates an empty HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p8960175818213">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p76012252218">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen18414225172212"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">();</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_empty</span><span class="w"> </span>
<span class="c1">-----------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x118b7f</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li294513342287">hll_empty(int32 log2m)<p id="EN-US_TOPIC_0000001145830495__p1831211171982"><a name="EN-US_TOPIC_0000001145830495__li294513342287"></a><a name="li294513342287"></a>Description: Creates an empty HLL and sets the <strong id="EN-US_TOPIC_0000001145830495__b1984021117191">log2m</strong> parameter. The parameter value ranges from 10 to 16.</p>
<p id="EN-US_TOPIC_0000001145830495__p131216177814">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p14312117989">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen1397418303228"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="w"> </span><span class="k">select</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">(</span><span class="mi">10</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_empty</span><span class="w"> </span>
<span class="c1">-----------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x118a7f</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li14981621015">hll_empty(int32 log2m, int32 regwidth)<p id="EN-US_TOPIC_0000001145830495__p16155163916101"><a name="EN-US_TOPIC_0000001145830495__li14981621015"></a><a name="li14981621015"></a>Description: Creates an empty HLL and sets the <strong id="EN-US_TOPIC_0000001145830495__b16692457191918">log2m</strong> and <strong id="EN-US_TOPIC_0000001145830495__b53357213202">regwidth</strong> parameters in sequence. The value of <strong id="EN-US_TOPIC_0000001145830495__b85081216508">regwidth</strong> ranges from 1 to 5.</p>
<p id="EN-US_TOPIC_0000001145830495__p11155193920102">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p1615553912105">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen1648416394220"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_empty</span><span class="w"> </span>
<span class="c1">-----------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x116a7f</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li65635587126">hll_empty(int32 log2m, int32 regwidth, int64 expthresh)<p id="EN-US_TOPIC_0000001145830495__p182001115141314"><a name="EN-US_TOPIC_0000001145830495__li65635587126"></a><a name="li65635587126"></a>Description: Creates an empty HLL and sets the <strong id="EN-US_TOPIC_0000001145830495__b1737083012200">log2m</strong>, <strong id="EN-US_TOPIC_0000001145830495__b5339123220205">regwidth</strong>, and <strong id="EN-US_TOPIC_0000001145830495__b07702035182010">expthresh</strong> parameters. The value of <strong id="EN-US_TOPIC_0000001145830495__b780316591673">expthresh</strong> is an integer ranging from –1 to 7. This parameter specifies the threshold for switching from the <strong id="EN-US_TOPIC_0000001145830495__b165034260816">explicit</strong> mode to the <strong id="EN-US_TOPIC_0000001145830495__b15046268810">sparse</strong> mode. <strong id="EN-US_TOPIC_0000001145830495__b118741382503">–1</strong> indicates the auto mode; <strong id="EN-US_TOPIC_0000001145830495__b1187563865017">0</strong> indicates that the <strong id="EN-US_TOPIC_0000001145830495__b148771538195012">explicit</strong> mode is skipped; a value from 1 to 7 indicates that the mode is switched when the number of distinct values reaches 2<sup id="EN-US_TOPIC_0000001145830495__sup28794386501"><strong id="EN-US_TOPIC_0000001145830495__b0878163895014">expthresh</strong></sup>.</p>
<p id="EN-US_TOPIC_0000001145830495__p1533061014228">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p52001515121313">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen6621144512210"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="w"> </span><span class="k">select</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">,</span><span class="w"> </span><span class="mi">7</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_empty</span><span class="w"> </span>
<span class="c1">-----------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x116a48</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li15202125961520">hll_empty(int32 log2m, int32 regwidth, int64 expthresh, int32 sparseon)<p id="EN-US_TOPIC_0000001145830495__p158132614212"><a name="EN-US_TOPIC_0000001145830495__li15202125961520"></a><a name="li15202125961520"></a>Description: Creates an empty HLL and sets the <strong id="EN-US_TOPIC_0000001145830495__b1975693492119">log2m</strong>, <strong id="EN-US_TOPIC_0000001145830495__b177113452119">regwidth</strong>, <strong id="EN-US_TOPIC_0000001145830495__b13771634172119">expthresh</strong>, and <strong id="EN-US_TOPIC_0000001145830495__b1123985015212">sparseon</strong> parameters. The value of <strong id="EN-US_TOPIC_0000001145830495__b62752056142110">sparseon</strong> is <strong id="EN-US_TOPIC_0000001145830495__b1067005842119">0</strong> or <strong id="EN-US_TOPIC_0000001145830495__b03959117225">1</strong>.</p>
<p id="EN-US_TOPIC_0000001145830495__p981376152115">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p88135612218">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen146220508225"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="w"> </span><span class="k">select</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span><span class="mi">4</span><span class="p">,</span><span class="mi">7</span><span class="p">,</span><span class="mi">0</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_empty</span><span class="w"> </span>
<span class="c1">-----------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x116a08</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li7789448142212">hll_add(hll, hll_hashval)<p id="EN-US_TOPIC_0000001145830495__p1941515252311"><a name="EN-US_TOPIC_0000001145830495__li7789448142212"></a><a name="li7789448142212"></a>Description: Adds hll_hashval to an HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p1441738112410">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p88702122243">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen108071136122412"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_add</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_add</span><span class="w"> </span>
<span class="c1">--------------------------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x128b7f8895a3f5af28cafe</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li463515414247">hll_add_rev(hll_hashval, hll)<p id="EN-US_TOPIC_0000001145830495__p1288656122519"><a name="EN-US_TOPIC_0000001145830495__li463515414247"></a><a name="li463515414247"></a>Description: Adds hll_hashval to an HLL. This function works the same as hll_add, except that the positions of parameters are switched.</p>
<p id="EN-US_TOPIC_0000001145830495__p227181912514">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p1135502417257">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen209187392252"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_add_rev</span><span class="p">(</span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">),</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">());</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_add_rev</span><span class="w"> </span>
<span class="c1">--------------------------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x128b7f8895a3f5af28cafe</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1137144442511">hll_eq(hll, hll)<p id="EN-US_TOPIC_0000001145830495__p958916318260"><a name="EN-US_TOPIC_0000001145830495__li1137144442511"></a><a name="li1137144442511"></a>Description: Compares two HLLs to check whether they are the same.</p>
<p id="EN-US_TOPIC_0000001145830495__p49961415192612">Return type: bool</p>
<p id="EN-US_TOPIC_0000001145830495__p390213219261">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen1455873692616"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_eq</span><span class="p">(</span><span class="n">hll_add</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">)),</span><span class="w"> </span><span class="n">hll_add</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">2</span><span class="p">)));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_eq</span><span class="w"> </span>
<span class="c1">--------</span>
<span class="w"> </span><span class="n">f</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li17480164332619">hll_ne(hll, hll)<p id="EN-US_TOPIC_0000001145830495__p122916532719"><a name="EN-US_TOPIC_0000001145830495__li17480164332619"></a><a name="li17480164332619"></a>Description: Compares two HLLs to check whether they are different.</p>
<p id="EN-US_TOPIC_0000001145830495__p585731542715">Return type: bool</p>
<p id="EN-US_TOPIC_0000001145830495__p12888131922719">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen335754922717"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_ne</span><span class="p">(</span><span class="n">hll_add</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">)),</span><span class="w"> </span><span class="n">hll_add</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">2</span><span class="p">)));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_ne</span><span class="w"> </span>
<span class="c1">--------</span>
<span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li76541539271">hll_cardinality(hll)<p id="EN-US_TOPIC_0000001145830495__p73021312817"><a name="EN-US_TOPIC_0000001145830495__li76541539271"></a><a name="li76541539271"></a>Description: Calculates the number of distinct values of an HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p15436113019288">Return type: int</p>
<p id="EN-US_TOPIC_0000001145830495__p379673532815">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen71391529282"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_cardinality</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_cardinality</span><span class="w"> </span>
<span class="c1">-----------------</span>
<span class="w"> </span><span class="mi">1</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li650195610286">hll_union(hll, hll)<p id="EN-US_TOPIC_0000001145830495__p742361232918"><a name="EN-US_TOPIC_0000001145830495__li650195610286"></a><a name="li650195610286"></a>Description: Performs the <strong id="EN-US_TOPIC_0000001145830495__b18279978475">UNION</strong> operation on two HLL data structures to obtain one HLL.</p>
<p id="EN-US_TOPIC_0000001145830495__p1193813916294">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p4673204419296">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen1270611814308"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="n">hll_union</span><span class="p">(</span><span class="n">hll_add</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">)),</span><span class="w"> </span><span class="n">hll_add</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">(),</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">2</span><span class="p">)));</span><span class="w"></span>
<span class="w"> </span><span class="n">hll_union</span><span class="w"> </span>
<span class="c1">------------------------------------------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x128b7f8895a3f5af28cafeda0ce907e4355b60</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
<div class="section" id="EN-US_TOPIC_0000001145830495__section121531551417"><h4 class="sectiontitle">Built-in Functions</h4><p id="EN-US_TOPIC_0000001145830495__p163082041204910">HLL has a series of built-in functions for internal data processing. Generally, users do not need to know how to use these functions. For details, see <a href="#EN-US_TOPIC_0000001145830495__table47911935194712">Table 1</a>.</p>
</div>
<div class="tablenoborder"><a name="EN-US_TOPIC_0000001145830495__table47911935194712"></a><a name="table47911935194712"></a><table cellpadding="4" cellspacing="0" summary="" id="EN-US_TOPIC_0000001145830495__table47911935194712" frame="border" border="1" rules="all"><caption><b>Table 1 </b>Built-in functions</caption><thead align="left"><tr id="EN-US_TOPIC_0000001145830495__row77911435104713"><th align="left" class="cellrowborder" valign="top" width="24.48%" id="mcps1.3.12.2.3.1.1"><p id="EN-US_TOPIC_0000001145830495__p2791143544719">Function</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="75.52%" id="mcps1.3.12.2.3.1.2"><p id="EN-US_TOPIC_0000001145830495__p9791835174713">Description</p>
</th>
</tr>
</thead>
<tbody><tr id="EN-US_TOPIC_0000001145830495__row1879183513479"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p1179193510478">hll_in</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p1979119357477">Receives hll data in string format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row1479111356473"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p279183512474">hll_out</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p3791143534720">Sends hll data in string format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row17791143519475"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p179143534719">hll_recv</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p19791133504717">Receives hll data in bytea format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row37911735174717"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p579113584717">hll_send</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p27911635154716">Sends hll data in bytea format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row1079119355476"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p879173514479">hll_trans_in</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p1479112358470">Receives hll_trans_type data in string format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row1679111357471"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p19791103544713">hll_trans_out</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p379103574716">Sends hll_trans_type data in string format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row279110357470"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p379193517476">hll_trans_recv</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p187911359479">Receives hll_trans_type data in bytea format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row1679123516479"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p1579193513473">hll_trans_send</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p4791235144715">Sends hll_trans_type data in bytea format.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row10791193515474"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p13791103513474">hll_typmod_in</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p7791835124712">Receives typmod data.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row167911235114720"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p1791123516471">hll_typmod_out</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p17918354472">Sends typmod data.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row20791193513473"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p117911835204715">hll_hashval_in</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p1779111354473">Receives hll_hashval data.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row13791173594711"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p167911235154711">hll_hashval_out</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p4791163594716">Sends hll_hashval data.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row9791435194716"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p18791335114717">hll_add_trans0</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p117915355473">Works similar to hll_add, and is used on the first phase of DNs in distributed aggregation operations.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row12791103520475"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p2791143513476">hll_union_trans</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p7791103544717">Works similar to hll_union, and is used on the first phase of DNs in distributed aggregation operations.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row15791133515478"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p1879133524717">hll_union_collect</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p179110357477">Works similar to hll_union, and is used on the second phase of CNs in distributed aggregation operations to summarize the results of each DN.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row47911535164716"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p1479111359471">hll_pack</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p579114359471">Is used on the third phase of CNs in distributed aggregation operations to convert a user-defined type hll_trans_type to the hll type.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row1179173574716"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p17791635184719">hll</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p879183564713">Converts a hll type to another hll type. Input parameters can be specified.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row107913352479"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p879153518477">hll_hashval</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p67911135194720">Converts the bigint type to the hll_hashval type.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145830495__row14791143519470"><td class="cellrowborder" valign="top" width="24.48%" headers="mcps1.3.12.2.3.1.1 "><p id="EN-US_TOPIC_0000001145830495__p1079123544713">hll_hashval_int4</p>
</td>
<td class="cellrowborder" valign="top" width="75.52%" headers="mcps1.3.12.2.3.1.2 "><p id="EN-US_TOPIC_0000001145830495__p279110352479">Converts the int4 type to the hll_hashval type.</p>
</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="EN-US_TOPIC_0000001145830495__section0622234841"><h4 class="sectiontitle">Operators</h4><ul id="EN-US_TOPIC_0000001145830495__ul46536203527"><li id="EN-US_TOPIC_0000001145830495__li116531820165213">=<p id="EN-US_TOPIC_0000001145830495__p1290875111157"><a name="EN-US_TOPIC_0000001145830495__li116531820165213"></a><a name="li116531820165213"></a>Description: Compares the values of hll and hll_hashval types to check whether they are the same.</p>
<p id="EN-US_TOPIC_0000001145830495__p1579811138169">Return type: bool</p>
<p id="EN-US_TOPIC_0000001145830495__p10751141881610">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen196755372168"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span></pre></div></td><td class="code"><div><pre><span></span><span class="c1">--hll</span>
<span class="k">select</span><span class="w"> </span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">))</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">));</span><span class="w"></span>
<span class="k">column</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
<span class="c1">--hll_hashval</span>
<span class="k">select</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="o">?</span><span class="k">column</span><span class="o">?</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</div>
<ul id="EN-US_TOPIC_0000001145830495__ul747015462150"><li id="EN-US_TOPIC_0000001145830495__li12661524164">&lt;&gt; or !=<p id="EN-US_TOPIC_0000001145830495__p950315931712"><a name="EN-US_TOPIC_0000001145830495__li12661524164"></a><a name="li12661524164"></a>Description: Compares the values of hll and hll_hashval types to check whether they are different.</p>
<p id="EN-US_TOPIC_0000001145830495__p7269162212177">Return type: bool</p>
<p id="EN-US_TOPIC_0000001145830495__p561683021714">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen3694196111819"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span></pre></div></td><td class="code"><div><pre><span></span><span class="c1">--hll</span>
<span class="k">select</span><span class="w"> </span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">))</span><span class="w"> </span><span class="o">&lt;&gt;</span><span class="w"> </span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">2</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="o">?</span><span class="k">column</span><span class="o">?</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
<span class="c1">--hll_hashval</span>
<span class="k">select</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="o">&lt;&gt;</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">2</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="o">?</span><span class="k">column</span><span class="o">?</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li1658419151180">||<p id="EN-US_TOPIC_0000001145830495__p8976833171810"><a name="EN-US_TOPIC_0000001145830495__li1658419151180"></a><a name="li1658419151180"></a>Description: Represents the functions of hll_add, hll_union, and hll_add_rev.</p>
<p id="EN-US_TOPIC_0000001145830495__p12773165317187">Return type: hll</p>
<p id="EN-US_TOPIC_0000001145830495__p449295812188">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen188043271192"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span>
<span class="normal">14</span>
<span class="normal">15</span>
<span class="normal">16</span>
<span class="normal">17</span>
<span class="normal">18</span>
<span class="normal">19</span>
<span class="normal">20</span></pre></div></td><td class="code"><div><pre><span></span><span class="c1">--hll_add</span>
<span class="k">select</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span><span class="w"></span>
<span class="w"> </span><span class="o">?</span><span class="k">column</span><span class="o">?</span><span class="w"> </span>
<span class="c1">--------------------------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x128b7f8895a3f5af28cafe</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
<span class="w"> </span>
<span class="c1">--hll_add_rev</span>
<span class="k">select</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_empty</span><span class="p">();</span><span class="w"></span>
<span class="w"> </span><span class="o">?</span><span class="k">column</span><span class="o">?</span><span class="w"> </span>
<span class="c1">--------------------------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x128b7f8895a3f5af28cafe</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
<span class="w"> </span>
<span class="c1">--hll_union</span>
<span class="k">select</span><span class="w"> </span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">))</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">2</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="o">?</span><span class="k">column</span><span class="o">?</span><span class="w"> </span>
<span class="c1">------------------------------------------</span>
<span class="w"> </span><span class="err">\</span><span class="n">x128b7f8895a3f5af28cafeda0ce907e4355b60</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001145830495__li16979102211209">#<p id="EN-US_TOPIC_0000001145830495__p9230123062016"><a name="EN-US_TOPIC_0000001145830495__li16979102211209"></a><a name="li16979102211209"></a>Description: Calculates the number of distinct values of an HLL. It works the same as the hll_cardinality function.</p>
<p id="EN-US_TOPIC_0000001145830495__p1891854172018">Return type: int</p>
<p id="EN-US_TOPIC_0000001145830495__p7886845202013">For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001145830495__screen17918186172112"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">select</span><span class="w"> </span><span class="o">#</span><span class="p">(</span><span class="n">hll_empty</span><span class="p">()</span><span class="w"> </span><span class="o">||</span><span class="w"> </span><span class="n">hll_hash_integer</span><span class="p">(</span><span class="mi">1</span><span class="p">));</span><span class="w"></span>
<span class="w"> </span><span class="o">?</span><span class="k">column</span><span class="o">?</span><span class="w"> </span>
<span class="c1">----------</span>
<span class="w"> </span><span class="mi">1</span><span class="w"></span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span><span class="w"></span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_06_0027.html">Functions and Operators</a></div>
</div>
</div>
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