I am running versions 8.1.2 and I installed 8.2B last week. I dumped
the data from the old version into the new version. The db consists of
several million records. Total disk usage is approximately 114GB.
My two observations are as follows... Also, keep in mind these are truly
just observations, I didn't use any benchmarking tools. If someone can
point me to a link of performance tools, I'd be happy to try them and report
back!
1. The release notes indicate "more efficient vacuuming." However, both
vacuums seems to take about the same amount of time, ie. approx: 9 hours.
Does "more efficient" simply mean, less IO/CPU busyness? This one doesn't
really bother me, the next one does...
Here are my vacuum parms, I used the same ones for both versions, of
course.
----------
maintenance_work_mem = 400000 # Unnecessarily high, I know.... I left it
# for comparison's sake.
vacuum_cost_delay = 50
vacuum_cost_page_hit = 1
vacuum_cost_page_miss = 10
vacuum_cost_page_dirty = 20
vacuum_cost_limit = 2000
----------
2. I have a tsearch2 index which is 756MB in size in 8.1.2 but balloons to
910MB in 8.2! These numbers were taken right after a REINDEX. Normally, I
wouldn't care about physical index size, but this particular index is
sitting on a ramdisk, so size really does matter. I see that the tsearch2
type was diddled with in 8.2. Is this an intentional change to improve
tsearch2 performance?
Thank you for any advice or abuse you give. No. Wait. No abuse please.
Richard Whidden
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
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