[9.3 bug fix] backends emit hundreds of messages when statistics file is inaccessible
От | MauMau |
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Тема | [9.3 bug fix] backends emit hundreds of messages when statistics file is inaccessible |
Дата | |
Msg-id | F678F6772E314F38814968F6182753EE@maumau обсуждение исходный текст |
Ответы |
Re: [9.3 bug fix] backends emit hundreds of messages when statistics file is inaccessible
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Список | pgsql-hackers |
Hello, I've found a bug in PostgreSQL 9.3 beta 2 which is related to statistics collection which emits excesssive amount of error messages. Please find attached the patch to fix this. I confirmed this problem occurs in PostgreSQL 9.2, too. Could you backport this? [Problem] If the directory specified by stats_temp_directory becomes inaccessible to postgres, enormous amount of WARNING messages are output. For example, when I set wrong permission on the directory by mistake while the database server is running and then started psql, more than 600 messages were emitted in a few seconds like this: WARNING: could not open statistics file "/work/maumau/stats_tmp/pgstat.stat": Permission denied LOG: could not open temporary statistics file "/work/maumau/stats_tmp/pgstat.tmp": Permission denied WARNING: could not open statistics file "/work/maumau/stats_tmp/pgstat.stat": Permission denied WARNING: could not open statistics file "/work/maumau/stats_tmp/pgstat.stat": Permission denied WARNING: could not open statistics file "/work/maumau/stats_tmp/pgstat.stat": Permission denied ... Even when there's no client, these messages are output regularly. I guess this is because autovacuum runs. [Cause] In backend_read_statsfile(), the backend loops PGSTAT_POLL_LOOP_COUNT (=1000) times trying to open the statistics file. The backend emits a WARNING message if it fails to open the file in every iteration of the loop. [How to fix] Emit the message upon the first failed attempt. For some diagnostics purposes, emit the message with DEBUG2 level on the subsequent attempts. DEBUG2 is arbitrary. Regards MauMau
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