Re: Shared buffers, db transactions commited, and write IO on Solaris

Erik Jones <erik@myemma.com> writes:

We've recently made a couple changes to our system that have resulted  

in a drastic increase in performance as well as some very confusing  

changes to the database statistics, specifically  

pg_stat_database.xact_commit.  Here's the details:

I'm kinda boggled too.  I can see how increasing shared buffers could

result in a drastic reduction in write rate, if the working set of your

queries fits in the new space but didn't fit in the old.  I have no idea

how that leads to a drop in number of transactions committed though.

It doesn't make sense that autovac would run less frequently, because

it's driven by number of tuples changed not number of disk writes; and

that could hardly account for a 10x drop anyway.

Did you by any chance take note of exactly which processes were

generating all the I/O or the CPU load?