huge pgstat.stat file on PostgreSQL 8.3.24

Hi group,

We’ve found huge pgstat.stat file on our production DB boxes, the size is over 100MB. autovacuum is enabled. So my question would be:

1.       What’s a reasonable size of pgstat.stat file, can it be estimated?

2.       What’s the safest way to reduce the file size to alleviate the IO impact on disk?

3.       If need to drop all statistics, would a “analyze DB” command enough to eliminate the performance impact on queries?

Thanks,

Suya