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| <h1 class="title topictitle1" id="ariaid-title1">ALTER VIEW Statement</h1> |
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| <div class="body conbody"> |
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| <p class="p"> |
| The <code class="ph codeph">ALTER VIEW</code> statement changes the characteristics of a view. |
| </p> |
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| <p class="p"> |
| Because a view is a logical construct, an alias for a query, with no physical data behind |
| it, <code class="ph codeph">ALTER VIEW</code> only involves changes to metadata in the metastore |
| database, not any data files in HDFS. |
| </p> |
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| <p class="p"> |
| To see the definition of the updated view, issue a <code class="ph codeph">DESCRIBE FORMATTED</code> |
| statement. |
| </p> |
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| <p class="p"> |
| <strong class="ph b">Syntax:</strong> |
| </p> |
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| <pre class="pre codeblock"><code>ALTER VIEW [<var class="keyword varname">database_name</var>.]<var class="keyword varname">view_name</var> |
| [(<var class="keyword varname">column_name</var> [COMMENT '<var class="keyword varname">column_comment</var>'][, ...])] |
| AS <var class="keyword varname">select_statement</var>; |
| |
| ALTER VIEW [<var class="keyword varname">database_name</var>.]<var class="keyword varname">view_name</var> |
| RENAME TO [<var class="keyword varname">database_name</var>.]<var class="keyword varname">view_name</var>; |
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| ALTER VIEW [<var class="keyword varname">database_name</var>.]<var class="keyword varname">view_name</var> SET OWNER USER user_name; |
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| ALTER VIEW [<var class="keyword varname">database_name</var>.]<var class="keyword varname">view_name</var> |
| SET TBLPROPERTIES ('<var class="keyword varname">name</var>' = '<var class="keyword varname">value</var>'[, '<var class="keyword varname">name</var>' = '<var class="keyword varname">value</var>' ...]); |
| |
| ALTER VIEW [<var class="keyword varname">database_name</var>.]<var class="keyword varname">view_name</var> |
| UNSET TBLPROPERTIES ('<var class="keyword varname">name</var>'[, ...]); |
| </code></pre> |
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| <ul class="ul"> |
| <li class="li"> |
| The <code class="ph codeph">AS</code> clause associates the view with a different query. |
| <p class="p"> |
| An optional list of column names can be specified with or without the column-level |
| comments. |
| </p> |
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| <div class="p"> |
| For example: |
| <pre class="pre codeblock"><code> |
| ALTER VIEW v1 AS SELECT x, UPPER(s) s FROM t2; |
| ALTER VIEW v1 (c1, c2) AS SELECT x, UPPER(s) s FROM t2; |
| ALTER VIEW v7 (c1 COMMENT 'Comment for c1', c2) AS SELECT t1.c1, t1.c2 FROM t1; |
| </code></pre> |
| </div> |
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| </li> |
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| <li class="li"> |
| The <code class="ph codeph">RENAME TO</code> clause changes the name of the view, moves the view to a |
| different database, or both. |
| <div class="p"> |
| For example: |
| <pre class="pre codeblock"><code>ALTER VIEW db1.v1 RENAME TO db2.v2; -- Move the view to a different database with a new name. |
| ALTER VIEW db1.v1 RENAME TO db1.v2; -- Rename the view in the same database. |
| ALTER VIEW db1.v1 RENAME TO db2.v1; -- Move the view to a difference database with the same view name.</code></pre> |
| </div> |
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| </li> |
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| <li class="li"> |
| The <code class="ph codeph">SET OWNER</code> clause transfers the ownership of the view from the |
| current owner to another user. |
| <p class="p"> |
| The view owner is originally set to the user who creates the view. |
| The term <code class="ph codeph">OWNER</code> is used to differentiate between the |
| <code class="ph codeph">ALL</code> privilege that is explicitly granted via the |
| <code class="ph codeph">GRANT</code> statement and a privilege that is implicitly granted by the |
| <code class="ph codeph">CREATE VIEW</code> statement. |
| </p> |
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| </li> |
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| <li class="li"> |
| The <code class="ph codeph">SET TBLPROPERTIES</code> clause is primarily a way to associate arbitrary |
| user-specified data items with a particular view. |
| <p class="p"> |
| You can associate arbitrary items of metadata with a table by specifying the |
| <code class="ph codeph">TBLPROPERTIES</code> clause. This clause takes a comma-separated list of |
| key-value pairs and stores those items in the metastore database. You can also unset the |
| view properties later with an <code class="ph codeph">UNSET TBLPROPERTIES</code> clause. |
| </p> |
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| <div class="p"> |
| For example: |
| <pre class="pre codeblock"><code>ALTER VIEW v1 SET TBLPROPERTIES ('tblp1' = '1', 'tblp2' = '2'); |
| ALTER VIEW v1 UNSET TBLPROPERTIES ('tblp1', 'tblp2'); |
| </code></pre> |
| </div> |
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| </li> |
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| </ul> |
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| <p class="p"> |
| <strong class="ph b">Statement type:</strong> DDL |
| </p> |
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| <p class="p"> |
| If you connect to different Impala nodes within an <span class="keyword cmdname">impala-shell</span> |
| session for load-balancing purposes, you can enable the <code class="ph codeph">SYNC_DDL</code> query |
| option to make each DDL statement wait before returning, until the new or changed |
| metadata has been received by all the Impala nodes. See |
| <a class="xref" href="../shared/../topics/impala_sync_ddl.html#sync_ddl">SYNC_DDL Query Option</a> for details. |
| </p> |
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| <p class="p"> |
| <strong class="ph b">Security considerations:</strong> |
| </p> |
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| <p class="p"> |
| If these statements in your environment contain sensitive literal values such as credit |
| card numbers or tax identifiers, Impala can redact this sensitive information when |
| displaying the statements in log files and other administrative contexts. See |
| <span class="xref">the documentation for your Apache Hadoop distribution</span> for details. |
| </p> |
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| <p class="p"> |
| <strong class="ph b">Cancellation:</strong> Cannot be cancelled. |
| </p> |
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| <p class="p"> |
| <strong class="ph b">HDFS permissions:</strong> This statement does not touch any HDFS files or directories, |
| therefore no HDFS permissions are required. |
| </p> |
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| <p class="p"> |
| <strong class="ph b">Related information:</strong> |
| </p> |
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| <p class="p"> |
| <a class="xref" href="impala_views.html#views">Overview of Impala Views</a>, <a class="xref" href="impala_create_view.html#create_view">CREATE VIEW Statement</a>, |
| <a class="xref" href="impala_drop_view.html#drop_view">DROP VIEW Statement</a> |
| </p> |
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| </div> |
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| <div class="related-links"> |
| <div class="familylinks"> |
| <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_langref_sql.html">Impala SQL Statements</a></div> |
| </div> |
| </div></body> |
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