Re: Vacuum Problems (locking)

Mike Goldner wrote:
> I have a nightly vacuum scheduled as follows:
>
> su - postgres -c "/usr/bin/vacuumdb --analyze --dbname=mydb"
>
> Last night, it appears that the vacuum blocked db access from my
> application server (JBoss). Here is the logfile snippet:
>
> [3693-jbossdb-postgres-2006-10-25 06:52:29.488 EDT]NOTICE: number of
> page slots needed (559472) exceeds max_fsm_pages (200000)
> [3693-jbossdb-postgres-2006-10-25 06:52:29.488 EDT]HINT: Consider
> increasing the configuration parameter "max_fsm_pages" to a value over
> 559472.
> [3693-jbossdb-postgres-2006-10-25 06:52:29.488 EDT]LOG: number of page
> slots needed (559472) exceeds max_fsm_pages (200000)
> [3693-jbossdb-postgres-2006-10-25 06:52:29.488 EDT]HINT: Consider
> increasing the configuration parameter "max_fsm_pages" to a value over
> 559472.
> [3693-jbossdb-postgres-2006-10-25 06:52:29.530 EDT]LOG: transaction ID
> wrap limit is 1073813592, limited by database "benchpg"
> [3693-jbossdb-postgres-2006-10-25 06:52:29.530 EDT]LOG: transaction ID
> wrap limit is 1073813592, limited by database "benchpg"
> [3693-jbossdb-postgres-2006-10-25 06:52:29.530 EDT]LOG: duration:
> 10224738.050 ms statement: VACUUM ANALYZE;
>
> First of all, my max_fsm_pages is obviously way off. However, every
> time I increase my max_fsm_pages the next vacuum says that it requires
> more. Will there every be a plateau in the requested pages? What is
> the impact of exceeding the pages slots needed?

You will need to vacuum full and if your need continues to grow, you
need to vacuum more.

> The only semi-unusual characteristic of my database is that I have one
> table in particular that grows and shrinks dramatically. My entire
> database after a vacuum --full is about 8GB. However, after a day or
> two, the db will grow as large as 75GB. Truncating that one table
> (since it empties regularly) will shrink the db right back to the 8GB.

Vacuum that single table, ALOT.

Sincerely,

Joshua D. Drake

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