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Lu, Huayi e6fa411af0 DWS DEV 830.201 version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2024-05-16 07:24:04 +00:00

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<a name="EN-US_TOPIC_0000001188642102"></a><a name="EN-US_TOPIC_0000001188642102"></a>
<h1 class="topictitle1">Querying Data on OBS Through Foreign Tables</h1>
<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_section42051157305"><h4 class="sectiontitle">Viewing Data on OBS by Directly Querying the Foreign Table</h4><p id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p108158220156">If the data amount is small, you can directly run <strong id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_b842352706114858">SELECT</strong> to query the foreign table and view the data on OBS.</p>
<ol id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_ol18171133519553"><li id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_li149753914557"><span>Run the following command to query data from the foreign table:</span><p><div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_screen1649716395554"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</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="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">product_info_ext_obs</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p48753336403">If the query result is the same as the data in <a href="dws_04_0243.html#EN-US_TOPIC_0000001188482188__en-us_topic_0000001145410931_en-us_topic_0102810712_en-us_topic_0093837401_section1888720568453">Original Data</a>, the import is successful. The following information is displayed at the end of the query result:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_screen0184956124218"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="p">(</span><span class="mi">10</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p164991939165510">After data is queried, you can insert the data to common tables in the database.</p>
</p></li></ol>
</div>
<div class="section" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_section152121815193012"><a name="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_section152121815193012"></a><a name="en-us_topic_0000001099130958_en-us_topic_0102810710_section152121815193012"></a><h4 class="sectiontitle">Querying Data After Importing It</h4><ol id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_ol19756112118416"><li id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_li57561212420"><span>Create a table in <span id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_ph1692512422530">GaussDB(DWS)</span> to store imported data.</span><p><p id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p1263149111210">The target table structure must be the same as the structure of the foreign table created in <a href="dws_04_0245.html">Creating a Foreign Table</a>. That is, both tables must have the same number of columns and column types.</p>
<p id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p1846511513104">For example, create a table named <em id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_i842352697171046">product_info</em>. The table example is as follows:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_screen17865118123918"><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>
<span class="normal">21</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">DROP</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="n">product_info</span><span class="p">;</span>
<span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">product_info</span>
<span class="p">(</span>
<span class="w"> </span><span class="n">product_price</span><span class="w"> </span><span class="nb">integer</span><span class="w"> </span><span class="k">not</span><span class="w"> </span><span class="k">null</span><span class="p">,</span>
<span class="w"> </span><span class="n">product_id</span><span class="w"> </span><span class="nb">char</span><span class="p">(</span><span class="mi">30</span><span class="p">)</span><span class="w"> </span><span class="k">not</span><span class="w"> </span><span class="k">null</span><span class="p">,</span>
<span class="w"> </span><span class="n">product_time</span><span class="w"> </span><span class="nb">date</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_level</span><span class="w"> </span><span class="nb">char</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_name</span><span class="w"> </span><span class="nb">varchar</span><span class="p">(</span><span class="mi">200</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_type1</span><span class="w"> </span><span class="nb">varchar</span><span class="p">(</span><span class="mi">20</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_type2</span><span class="w"> </span><span class="nb">char</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_monthly_sales_cnt</span><span class="w"> </span><span class="nb">integer</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_comment_time</span><span class="w"> </span><span class="nb">date</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_comment_num</span><span class="w"> </span><span class="nb">integer</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">product_comment_content</span><span class="w"> </span><span class="nb">varchar</span><span class="p">(</span><span class="mi">200</span><span class="p">)</span><span class="w"> </span>
<span class="p">)</span><span class="w"> </span>
<span class="k">with</span><span class="w"> </span><span class="p">(</span>
<span class="n">orientation</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">column</span><span class="p">,</span>
<span class="n">compression</span><span class="o">=</span><span class="n">middle</span>
<span class="p">)</span><span class="w"> </span>
<span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">HASH</span><span class="w"> </span><span class="p">(</span><span class="n">product_id</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</p></li><li id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_li4947547161213"><span>Run the <strong id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_b842352706155329">INSERT INTO.. SELECT ..</strong> command to import data from the foreign table to the target table.</span><p><p id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p7919143312475">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_screen1377164017472"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">INSERT</span><span class="w"> </span><span class="k">INTO</span><span class="w"> </span><span class="n">product_info</span><span class="w"> </span><span class="k">SELECT</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">product_info_ext_obs</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<div class="p" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p11951646143216">If information similar to the following is displayed, the data has been imported.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_en-us_topic_0067790278_s94af2c28f6a84fcaae4451dc06657b2c"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">INSERT</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="mi">10</span>
</pre></div></td></tr></table></div>
</div>
</div>
</p></li><li id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_li4116383617136"><span>Run the following <strong id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_b842352706155423">SELECT</strong> command to view data imported from OBS to <span id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_ph039828152817">GaussDB(DWS)</span>:</span><p><div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_screen669215472511"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</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="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">product_info</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_p785613361634">If the query result is the same as the data in <a href="dws_04_0243.html#EN-US_TOPIC_0000001188482188__en-us_topic_0000001145410931_en-us_topic_0102810712_en-us_topic_0093837401_section1888720568453">Original Data</a>, the import is successful. The following information is displayed at the end of the query result:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188642102__en-us_topic_0000001099130958_en-us_topic_0102810710_screen1085853616314"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="p">(</span><span class="mi">10</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</p></li></ol>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0155.html">Importing ORC or CarbonData Data from OBS</a></div>
</div>
</div>
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