Update is more affected( taking more time) than Select ( if Auto vacuum is not running) - Mailing list pgsql-performance

From Hemant Pandey
Subject Update is more affected( taking more time) than Select ( if Auto vacuum is not running)
Date
Msg-id OF546C1EDC.5ADA2404-ON65257070.0014275B-65257070.001632F8@flextronicssoftware.com
Whole thread Raw
Responses Re: Update is more affected( taking more time) than Select
List pgsql-performance



Hi All,
       I have an ODBC application( using postgres database) which has three
different operations. Each operation is having combination of SELECT and
UPDATE.

For example:
Operation A:            6 Fetch + 1 Update
Operation B:            9 Fetch
Operation C:            5 Fetch + 3 Update  ( Tables has 140 records)

I have run these operations while Auto Vacumm is running and observed the
time taken in thse operations. I found that Operation C is taking highest
time and A is the lowest.
So i inferrred that, UPDATE takes more time.

Now i run these operations again, without running Auto Vacuum. I observed
that, time taken for operation A & B is almost same but time for Operation
C is increasing.

I am not able to analyze, why only for operation C, time is increasing??
Does auto vacuum affects more on UPDATE.


Please help me to understand these things.

Thanks in advance.

Hemant

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