| <?xml version="1.0" encoding="UTF-8"?> |
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| <!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
| <concept id="comment"> |
| |
| <title>COMMENT Statement</title> |
| |
| <titlealts audience="PDF"> |
| |
| <navtitle>COMMENT</navtitle> |
| |
| </titlealts> |
| |
| <prolog> |
| <metadata> |
| <data name="Category" value="Impala"/> |
| <data name="Category" value="SQL"/> |
| <data name="Category" value="DDL"/> |
| <data name="Category" value="Tables"/> |
| <data name="Category" value="Hive"/> |
| <data name="Category" value="Metastore"/> |
| <data name="Category" value="ETL"/> |
| <data name="Category" value="Ingest"/> |
| <data name="Category" value="Developers"/> |
| <data name="Category" value="Data Analysts"/> |
| </metadata> |
| </prolog> |
| |
| <conbody> |
| |
| <p> |
| The <codeph>COMMENT</codeph> statement adds, changes, or removes a comment about a |
| database, a table, or a column. |
| </p> |
| |
| <p> |
| You can alternatively use the <codeph>CREATE</codeph> and <codeph>ALTER</codeph> |
| statements to add comments to the objects. |
| </p> |
| |
| <p> |
| You can view the comment on a database, a table, or a column using the |
| <codeph>SHOW</codeph> or <codeph>DESCRIBE</codeph> statement. |
| </p> |
| |
| <p conref="../shared/impala_common.xml#common/syntax_blurb"/> |
| |
| <codeblock>COMMENT ON DATABASE <varname>db_name</varname> IS {'<varname>comment</varname>' | NULL}</codeblock> |
| |
| <codeblock>COMMENT ON TABLE [<varname>db_name</varname>.]<varname>table_name</varname> IS {'<varname>comment</varname>' | NULL}</codeblock> |
| |
| <codeblock>COMMENT ON COLUMN [<varname>db_name</varname>.]<varname>table_name</varname>.<varname>column_name</varname> IS {'<varname>comment</varname>' | NULL}</codeblock> |
| |
| <p> |
| <b>Parameters:</b> |
| </p> |
| |
| <ul> |
| <li> |
| <varname>db_name</varname>: Specify the database name if not for the current database. |
| </li> |
| |
| <li> |
| <codeph>NULL</codeph>: If given for the comment, removes the existing comment. |
| </li> |
| |
| <li> |
| The <varname>comment</varname> string can be up to 256 characters long. |
| </li> |
| </ul> |
| |
| <p> |
| <b>Privileges required:</b> |
| </p> |
| |
| <p> |
| To add a comment, the <codeph>ALTER</codeph> privilege on the object is required. |
| </p> |
| |
| <p> |
| To view a comment, the <codeph>SELECT</codeph>, <codeph>INSERT</codeph>, or |
| <codeph>REFRESH</codeph> on the object is required. |
| </p> |
| |
| <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/> |
| |
| <p> |
| <b>Added in:</b> <keyword keyref="impala31"/> |
| </p> |
| |
| </conbody> |
| |
| </concept> |