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Queries using generator=categorymembers and gcmsort=timestamp intermittently return database errors.

Sample query URL:  http://en.wikipedia.org/w/api.php?action=query&generator=categorymembers&gcmtitle=Category:Wikipedia%20soft%20redirected%20categories&prop=info&gcmlimit=500&gcmsort=timestamp

Response:

<?xml version="1.0"?>
<api servedby="srv296">
  <error code="internal_api_error_DBQueryError" info="Database query error" xml:space="preserve">

#0 /usr/local/apache/common-local/php-1.17/includes/db/Database.php(734): DatabaseBase->reportQueryError('Query execution...', 1317, 'SELECT  page_na...', 'ApiQueryCategor...', false)
#1 /usr/local/apache/common-local/php-1.17/includes/db/Database.php(1033): DatabaseBase->query('SELECT  page_na...', 'ApiQueryCategor...')
#2 /usr/local/apache/common-local/php-1.17/includes/api/ApiQueryBase.php(263): DatabaseBase->select(Array, Array, Array, 'ApiQueryCategor...', Array, Array)
#3 /usr/local/apache/common-local/php-1.17/includes/api/ApiQueryCategoryMembers.php(161): ApiQueryBase->select('ApiQueryCategor...', Array)
#4 /usr/local/apache/common-local/php-1.17/includes/api/ApiQueryCategoryMembers.php(52): ApiQueryCategoryMembers->run(Object(ApiPageSet))
#5 /usr/local/apache/common-local/php-1.17/includes/api/ApiQuery.php(550): ApiQueryCategoryMembers->executeGenerator(Object(ApiPageSet))
#6 /usr/local/apache/common-local/php-1.17/includes/api/ApiQuery.php(246): ApiQuery->executeGeneratorModule(Object(ApiQueryCategoryMembers), Array)
#7 /usr/local/apache/common-local/php-1.17/includes/api/ApiMain.php(657): ApiQuery->execute()
#8 /usr/local/apache/common-local/php-1.17/includes/api/ApiMain.php(339): ApiMain->executeAction()
#9 /usr/local/apache/common-local/php-1.17/includes/api/ApiMain.php(323): ApiMain->executeActionWithErrorHandling()
#10 /usr/local/apache/common-local/php-1.17/api.php(116): ApiMain->execute()
#11 /usr/local/apache/common-local/live-1.5/api.php(3): require('/usr/local/apac...')
#12 {main}

</error>
</api>

As mentioned earlier, this error is intermittent.  I can submit the _identical_ query 10 times and it will only result in an error 2 or 3 times.  So far, I have not encountered any similar errors when the ordering is by sortkey.

I have encountered the same error when using list=categorymembers instead of generator=categorymembers.