We just did a bunch of maintenance on one of our production databases that
involved a lot of alter tables and moving records about and the like.
Afterwards, I did a vacuum full and analyze to get the database back on
track -- autovac maintains it under normal operations.
Today I decided to run reindex during a slow period, and was shocked to
find the database size drop from 165M to 30M. Keep in mind that the
165M is after vacuum full. So, apparently, there was 135M of index bloat?
That seems a little excessive to me, especially when the docs claim that
reindexing is usually not necessary.
This is PostgreSQL 8.1.4. We've got upgrades to 8.2 planned, but it's
going to be a few months before we can squeak that into a maintenance
window. Additionally, I thought all the big index improvements were
added in 7.4.
I guess my question is whether or not this is expected. It's obviously
not a good thing -- I've noticed that shared buffer usage has dropped
dramatically as well (from 28,000 to 7000). I hadn't expected index
bloat of this magnitude, and I'm concerned about when the database hits
2 or 3 G in size and has 12G just in indexes that take hours to rebuild.
--
Bill Moran
Collaborative Fusion Inc.
