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Posted to issues-all@impala.apache.org by "Andy Stadtler (JIRA)" <ji...@apache.org> on 2019/03/01 00:36:00 UTC
[jira] [Updated] (IMPALA-8265) Reject INSERT/UPSERT queries with
ORDER BY and no OFFSET/LIMIT
[ https://issues.apache.org/jira/browse/IMPALA-8265?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Andy Stadtler updated IMPALA-8265:
----------------------------------
Description:
Currently Impala doesn't honor a sort by without a limit or offset in a insert ... select operation. While we currently throw a warning it seems like this query should be rejected with the same message. Especially now with the UPSERT ability and Kudu its obvious logic to take a table of duplicate rows and use the following query.
{code:java}
UPSERT INTO kudu.table SELECT col1, col2, col3 FROM duplicate_row_table SORT BY timestamp_column ASC;{code}
Impala will happily take this query and write incorrect data. The same query works fine as a SELECT only query and it's easy to see where users would make the mistake of reusing it in an INSERT/UPSERT.
Rejecting the query with the warning message would make sure the user knew the sort by would not be honored and make sure they added a limit or changed their query logic.
{quote}*Sorting considerations:* Although you can specify an {{ORDER BY}} clause in an {{INSERT ... SELECT}} statement, any {{ORDER BY}} clause is ignored and the results are not necessarily sorted. An {{INSERT ... SELECT}} operation potentially creates many different data files, prepared on different data nodes, and therefore the notion of the data being stored in sorted order is impractical.
{quote}
was:
Currently Impala doesn't honor a sort by without a limit or offset in a insert ... select operation. While we currently throw a warning it seems like this query should be rejected with the same message. Especially now with the UPSERT ability and Kudu its obvious logic to take a table of duplicate rows and UPSERT INTO kudu.table SELECT col1, col2, col3 FROM duplicate_row_table SORT BY timestamp_column ASC. Impala will happily take this query and write incorrect data. The same query works fine as a SELECT only query and it's easy to see where users would make the mistake of reusing it in an INSERT/UPSERT.
Rejecting the query with the warning message would make sure the user knew the sort by would not be honored and make sure they added a limit or changed their query logic.
*Sorting considerations:* Although you can specify an {{ORDER BY}} clause in an {{INSERT ... SELECT}} statement, any {{ORDER BY}} clause is ignored and the results are not necessarily sorted. An {{INSERT ... SELECT}} operation potentially creates many different data files, prepared on different data nodes, and therefore the notion of the data being stored in sorted order is impractical.
> Reject INSERT/UPSERT queries with ORDER BY and no OFFSET/LIMIT
> ---------------------------------------------------------------
>
> Key: IMPALA-8265
> URL: https://issues.apache.org/jira/browse/IMPALA-8265
> Project: IMPALA
> Issue Type: Improvement
> Reporter: Andy Stadtler
> Priority: Critical
>
> Currently Impala doesn't honor a sort by without a limit or offset in a insert ... select operation. While we currently throw a warning it seems like this query should be rejected with the same message. Especially now with the UPSERT ability and Kudu its obvious logic to take a table of duplicate rows and use the following query.
> {code:java}
> UPSERT INTO kudu.table SELECT col1, col2, col3 FROM duplicate_row_table SORT BY timestamp_column ASC;{code}
> Impala will happily take this query and write incorrect data. The same query works fine as a SELECT only query and it's easy to see where users would make the mistake of reusing it in an INSERT/UPSERT.
>
> Rejecting the query with the warning message would make sure the user knew the sort by would not be honored and make sure they added a limit or changed their query logic.
>
> {quote}*Sorting considerations:* Although you can specify an {{ORDER BY}} clause in an {{INSERT ... SELECT}} statement, any {{ORDER BY}} clause is ignored and the results are not necessarily sorted. An {{INSERT ... SELECT}} operation potentially creates many different data files, prepared on different data nodes, and therefore the notion of the data being stored in sorted order is impractical.
> {quote}
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