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https://issues.apache.org/jira/browse/IMPALA-11337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17577031#comment-17577031
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ASF subversion and git services commented on IMPALA-11337:
----------------------------------------------------------
Commit 328eedf96725c1eafd29675eea89b72990a06d15 in impala's branch
refs/heads/branch-4.1.1 from Joe McDonnell
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=328eedf96 ]
IMPALA-11337: Flush row output before writing "Fetched X row(s)"
When redirecting stdout and stderr to a file, the
existing code can sometimes output the "Fetched X row(s)"
line before finishing the row output. e.g.
impala-shell -B -q "select 1" >> outfile.txt 2>> outfile.txt
The rows output goes to stdout while the control messages
like "Fetched X row(s)" go to stderr. Since stdout can buffer
output, that can delay the output. This adds a flush for
stdout before writing the "Fetched X row(s)" message.
Testing:
- Added a shell test that redirects stdout and stderr to
a file and verifies the contents. This consistently
fails without the flush.
- Other shell tests pass
Change-Id: I83f89c110fd90d2d54331c7121e407d9de99146c
Reviewed-on: http://gerrit.cloudera.org:8080/18625
Reviewed-by: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
> impala-shell can output the "Fetched X row(s)" line before the actual results
> -----------------------------------------------------------------------------
>
> Key: IMPALA-11337
> URL: https://issues.apache.org/jira/browse/IMPALA-11337
> Project: IMPALA
> Issue Type: Bug
> Components: Clients
> Affects Versions: Impala 4.2.0
> Reporter: Joe McDonnell
> Assignee: Joe McDonnell
> Priority: Major
> Fix For: Impala 4.2.0
>
>
> In some scenarios, we are seeing that the "Fetched X row(s)" message is
> output before the actual data:
> {noformat}
> Query: SELECT * FROM test_table ORDER BY id DESC
> Query submitted at: 2022-06-02 23:53:48 (Coordinator:
> https://coordinator:25000)
> Query progress can be monitored at:
> https://coordinator:25000/query_plan?query_id=9d47858d6659cb87:2ccbdcdf00000000
> Fetched 1 row(s) in 1.59s
> 0 john 10{noformat}
> The "Fetched X row(s)" message is going to stderr and the results are going
> to stdout, so this is not covered completely by the current tests.
> Nonetheless, we should expect the "Fetched X row(s)" output to happen after
> the results data is written.
> We should add tests for this case and make sure that stdout is flushed prior
> to writing the "Fetched X row(s)" output.
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