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IMPALA-4730: [DOCS] DISTINCT is allowed with group_concat()

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Remove the "DISTINCT not allowed" restriction.

Add DISTINCT to syntax.

Add an example showing usage of DISTINCT.

Change-Id: Ib7d4555a5bc4c4195fa1529d1c1bdf39f98e7346
Reviewed-on: http://gerrit.cloudera.org:8080/7016
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: Impala Public Jenkins
This commit is contained in:
John Russell
2017-05-30 11:33:43 -07:00
committed by Impala Public Jenkins
parent f15589573b
commit 45e2329c92
1 changed files with 15 additions and 9 deletions
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24
docs/topics/impala_group_concat.xml
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@@ -45,9 +45,7 @@ under the License.
<p conref="../shared/impala_common.xml#common/syntax_blurb"/>
<!-- Might allow DISTINCT at some point. Check: does it allow ALL now? -->
<codeblock>GROUP_CONCAT([ALL] <varname>expression</varname> [, <varname>separator</varname>])</codeblock>
<codeblock>GROUP_CONCAT([ALL<ph rev="IMPALA-4730"> | DISTINCT</ph>] <varname>expression</varname> [, <varname>separator</varname>])</codeblock>
<p conref="../shared/impala_common.xml#common/concat_blurb"/>
@@ -61,12 +59,6 @@ under the License.
<b>Return type:</b> <codeph>STRING</codeph>
</p>
<p conref="../shared/impala_common.xml#common/restrictions_blurb"/>
<p>
You cannot apply the <codeph>DISTINCT</codeph> operator to the argument of this function.
</p>
<p conref="../shared/impala_common.xml#common/analytic_not_allowed_caveat"/>
<p>
@@ -98,6 +90,20 @@ under the License.
+---------------------------------+
| 1, 3, 2, 1 |
+---------------------------------+
</codeblock>
<p rev="IMPALA-4730">
Specify the <codeph>DISTINCT</codeph> keyword to eliminate duplicate values from
the concatenated result:
</p>
<codeblock rev="IMPALA-4730">
[localhost:21000] &gt; select group_concat(distinct s) from t1;
+--------------------------+
| group_concat(distinct s) |
+--------------------------+
| three, two, one |
+--------------------------+
</codeblock>
<p>