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Yang, Tong
6182f91ba8
Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Co-authored-by: Yang, Tong <yangtong2@huawei.com> Co-committed-by: Yang, Tong <yangtong2@huawei.com>
49 lines
6.7 KiB
HTML
49 lines
6.7 KiB
HTML
<a name="mrs_01_1431"></a><a name="mrs_01_1431"></a>
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<h1 class="topictitle1">ADD COLUMNS</h1>
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<div id="body1595920211683"><div class="section" id="mrs_01_1431__sa1cb229bf26b4a7a8efd1716defb63de"><h4 class="sectiontitle">Function</h4><p id="mrs_01_1431__ac917e6d6e78044e99179c0e0f5284232">This command is used to add a column to an existing table.</p>
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</div>
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<div class="section" id="mrs_01_1431__sc019b10a59e9426498a678c024d74f03"><h4 class="sectiontitle">Syntax</h4><p id="mrs_01_1431__ade33c61d12d049f8a0ab2538ce894440"><b><span class="cmdname" id="mrs_01_1431__cmdname67412714133">ALTER TABLE</span></b> <i><span class="varname" id="mrs_01_1431__v0218405770da4a66bab17413724b33ef">[db_name.]table_name</span></i> <b><span class="cmdname" id="mrs_01_1431__cmdname6841530161313">ADD COLUMNS</span></b> <i><span class="varname" id="mrs_01_1431__v1011a0e23107494faa79a92185d1e984">(col_name data_type,...)</span></i> <b><span class="cmdname" id="mrs_01_1431__cmdname11215183551319">TBLPROPERTIES</span></b><i><span class="varname" id="mrs_01_1431__v7a7ed8ecac4441d6978ef8caeb37cfc7">(''COLUMNPROPERTIES.columnName.shared_column'='sharedFolder.sharedColumnName,...', 'DEFAULT.VALUE.COLUMN_NAME'='default_value')</span></i>;</p>
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</div>
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<div class="section" id="mrs_01_1431__s253f086de08745ac890027c0b103cd7a"><h4 class="sectiontitle">Parameter Description</h4>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" id="mrs_01_1431__ta69e9ecdc1554375a8a1e844b14e00c5" frame="border" border="1" rules="all"><caption><b>Table 1 </b>ADD COLUMNS parameters</caption><thead align="left"><tr id="mrs_01_1431__r61ddb6139b8d4f4ca4a88c6389f8f327"><th align="left" class="cellrowborder" valign="top" width="24.89%" id="mcps1.3.3.2.2.3.1.1"><p id="mrs_01_1431__aeb0bfa560fb74f1f9e584cc1ef05bb9b">Parameter</p>
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</th>
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<th align="left" class="cellrowborder" valign="top" width="75.11%" id="mcps1.3.3.2.2.3.1.2"><p id="mrs_01_1431__ae81789e97e6d4953a8342f22d64feea9">Description</p>
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</th>
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</tr>
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</thead>
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<tbody><tr id="mrs_01_1431__re06e5e8fff8843fe84403c19e570e3f2"><td class="cellrowborder" valign="top" width="24.89%" headers="mcps1.3.3.2.2.3.1.1 "><p id="mrs_01_1431__afdc41077453c4291997170b1ab57f04d">db_name</p>
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</td>
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<td class="cellrowborder" valign="top" width="75.11%" headers="mcps1.3.3.2.2.3.1.2 "><p id="mrs_01_1431__a95e3427330524b4b9c6af41366afd1fd">Database name. If this parameter is not specified, the current database is selected.</p>
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</td>
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</tr>
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<tr id="mrs_01_1431__r4a578c7015ba461bab46a5c40c46256a"><td class="cellrowborder" valign="top" width="24.89%" headers="mcps1.3.3.2.2.3.1.1 "><p id="mrs_01_1431__ac25da7f69c964d93947693ed5b4006cb">table_name</p>
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</td>
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<td class="cellrowborder" valign="top" width="75.11%" headers="mcps1.3.3.2.2.3.1.2 "><p id="mrs_01_1431__a09288a5af7f44e36922b37de34446d94">Table name.</p>
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</td>
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</tr>
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<tr id="mrs_01_1431__rbf8f7998df2b40979c8e9e64d667e180"><td class="cellrowborder" valign="top" width="24.89%" headers="mcps1.3.3.2.2.3.1.1 "><p id="mrs_01_1431__a440446fee79947738959536aa886e611">col_name data_type</p>
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</td>
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<td class="cellrowborder" valign="top" width="75.11%" headers="mcps1.3.3.2.2.3.1.2 "><p id="mrs_01_1431__a9e6c31cb47f84b3d920a2ac5563ed7bf">Name of a comma-separated column with a data type. It consists of letters, digits, and underscores (_).</p>
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<div class="note" id="mrs_01_1431__n79385f1f99e34e9ba0fb44c3855905b0"><span class="notetitle"> NOTE: </span><div class="notebody"><p id="mrs_01_1431__a0d8c8a5cc97a443ab3aeca91f0a32caf">When creating a CarbonData table, do not name columns as tupleId, PositionId, and PositionReference because they will be used in UPDATE, DELETE, and secondary index commands.</p>
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</div></div>
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</td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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<div class="section" id="mrs_01_1431__s486ec4e997f847db995de2e1be1f7bd2"><h4 class="sectiontitle">Precautions</h4><ul id="mrs_01_1431__u456725972e234be3baabd062981672f5"><li id="mrs_01_1431__lece9b081af8349f6992997d485f6998d">Only <strong id="mrs_01_1431__b136478818147">shared_column</strong> and <strong id="mrs_01_1431__b166535813145">default_value</strong> are read. If any other property name is specified, no error will be thrown and the property will be ignored.</li><li id="mrs_01_1431__l6e33c715d5f44381b7b97ffacdd48aba">If no default value is specified, the default value of the new column is considered null.</li><li id="mrs_01_1431__le991932b5be84a29ad331d37e690b193">If filter is applied to the column, new columns will not be added during sort. New columns may affect query performance.</li></ul>
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</div>
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<div class="section" id="mrs_01_1431__s55536c9c534643ed8272f9f4b47fb407"><h4 class="sectiontitle">Examples</h4><ul id="mrs_01_1431__u7dd2908e171f4a26b31c6673dfeaf2fb"><li id="mrs_01_1431__lddf30cddf65b4e3498bf3a6bd89b853e"><b><span class="cmdname" id="mrs_01_1431__cmdname185932420135">ALTER TABLE</span></b> <i><span class="varname" id="mrs_01_1431__v2172a8dcc9fe4fcda54be7ae35bb8ab4">carbon</span></i> <b><span class="cmdname" id="mrs_01_1431__cmdname89938459132">ADD COLUMNS</span></b> <i><span class="varname" id="mrs_01_1431__vbfc8481653374de687e34a039f72b022">(a1 INT, b1 STRING)</span></i>;</li><li id="mrs_01_1431__l9ab1e9aec0134041bad78c69347a6300"><b><span class="cmdname" id="mrs_01_1431__cmdname10602121613143">ALTER TABLE</span></b> <i><span class="varname" id="mrs_01_1431__v60b2e595d2614db88d1aa949a8285b08">carbon</span></i> <b><span class="cmdname" id="mrs_01_1431__cmdname12509820191419">ADD COLUMNS</span></b> <i><span class="varname" id="mrs_01_1431__v72cc58def8dc451cba8702a11345c364">(a1 INT, b1 STRING)</span></i> <b><span class="cmdname" id="mrs_01_1431__cmdname979312233149">TBLPROPERTIES</span></b><i><span class="varname" id="mrs_01_1431__va825484497d94e2688035827e1f7f73a">('COLUMNPROPERTIES.b1.shared_column'='sharedFolder.b1')</span></i>;</li><li id="mrs_01_1431__l191b374e00ed4f32b5db2e9cbc9be7f6">ALTER TABLE <i><span class="varname" id="mrs_01_1431__ve7649af8bb3a44c795b3c3bf9d49682e">carbon</span></i> <b><span class="cmdname" id="mrs_01_1431__cmdname1119193216144">ADD COLUMNS</span></b> <i><span class="varname" id="mrs_01_1431__v4d5b6aef4581483da9aa7cff96ecf38e">(a1 INT, b1 STRING)</span></i> <b><span class="cmdname" id="mrs_01_1431__cmdname14776235121414">TBLPROPERTIES</span></b><i><span class="varname" id="mrs_01_1431__vf94331c1c4dd4fedad2e4f48e78d29d9">('DEFAULT.VALUE.a1'='10')</span></i>;</li></ul>
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</div>
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<div class="section" id="mrs_01_1431__sbd5eea8637c94038bf6a129ab9ca129f"><h4 class="sectiontitle">System Response</h4><p id="mrs_01_1431__ab3f2ebd199c342fb9103cbe4f02c7148">The newly added column can be displayed by running the <strong id="mrs_01_1431__b10167796128159">DESCRIBE</strong> command.</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="mrs_01_1424.html">DDL</a></div>
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</div>
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</div>
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