Цитат от Віталій Тимчишин <tivv00@xxxxxxxxx>:
May be you have very bad disk access times (e.g. slow random access)? In
this case everything should be OK while data in cache and awful, when not.
Could you check disk IO speed && IO wait while doing slow & fast query.
No, I think all is ok with disks. On my test server I have 8 SATA in
RAID 10 and on my production server I have 16 SATA in RAID10 dedicated
for pg data and also 8 SATA in RAID 10 for OS and pg_x_log and I do
not have any IO wait.
It is true, disks are much slower compared to RAM.
BTW: In this case, increasing shared buffers may help. At least this will
prevent other applications & AFAIK sequence scans to move your index data
from cache.
I will try to increase this value.
I think recomendation in docs was 1/4 from RAM, and on production
server I have it setup to 1/4 from RAM ( 32 GB).
Will os not cache the data from shared buffers for second time ?
The next step will be to move to pg 8.4, but I i twill tak etime for testing.
Best regards, Vitalii Tymchyshyn
regards,
ivan.
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