From: | "Chris Hoover" <revoohc(at)gmail(dot)com> |
---|---|
To: | "pgsql-admin(at)postgresql(dot)org Admin" <pgsql-admin(at)postgresql(dot)org> |
Subject: | Help calculating load values |
Date: | 2008-02-06 17:44:34 |
Message-ID: | 1d219a6f0802060944s55c3a5cbw61cf99010c2f863a@mail.gmail.com |
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Lists: | pgsql-admin |
I need some help calculating how much activity a query causes.
If I have a table defined as:
create table test_a (
col1 integer,
col2 char(1),
col3 varchar(35),
primary key (col1,col2)
) with oids;
When I do an "insert into test_a values (1,'a','test data');", does this
generate 3 writes (1 to table, 1 to index, and one to oid counter) and one
read (get oid from oid counter)?
What about when I do an "update test_a set col3='changed data' where col1 =
1 and col2 = 'a';"? I am thinking 5 writes (1 to old table tuple, 1 to old
index tuple, 1 to oid counter, 1 to new table tuple, one to new index tuple)
with 1 read (get oid from oid counter)?
Finally, what about the delete "delete from test_a where col1=1 and
col2='a';"? 2 writes (1 to table tuple, and 1 to index tuple)?
I am just trying to get a grasp on how much traffic I am creating for each
major dml statement we issue so that I can work with my sysadmin on some i/o
issues.
Thanks,
Chris
PG 8.1
RH 4
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