When I am using the following query, I got shared hit=8857.
EXPLAIN (buffers true, analyze) select * from act;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------
Seq Scan on act (cost=0.00..6308.82 rows=542312 width=735) (actual time=0.007..516.199 rows=542312 loops=1)
Buffers: shared hit=8857
Total runtime: 1004.067 ms
Wherears, when I am using the following query, I got Buffers: shared hit=416 read=46350
EXPLAIN (buffers true, analyze) select * from crm;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------
Seq Scan on crm (cost=0.00..21558.94 rows=1688234 width=333) (actual time=0.040..1738.903 rows=1688291 loops=1)
Buffers: shared hit=416 read=46350
Total runtime: 3257.872 ms
Could you please tell me why the different that is why I get read for one query and not for others?
Thanks.
On Thu, Sep 15, 2011 at 11:59 AM, Toby Corkindale <toby.corkindale@xxxxxxxxxxxxxxxxxxxx> wrote:
On 15/09/11 15:43, AI Rumman wrote:
Could anyone please tell me how to use all the options of explain in
Postgresql 9.
http://www.postgresql.org/docs/9.0/static/sql-explain.html
I can use EXPLAIN ANALYZE.explain (format yaml) select * from tab1;
But
explain (format yaml) analyze select * from tab1;
ERROR: syntax error at or near "analyze"
LINE 1: explain (format yaml) analyze select * from tab1
BUFFERS:
explain (buffers true) select * from tab1;
ERROR: EXPLAIN option BUFFERS requires ANALYZE
But
explain (buffers true) analyze select * from tab1;
ERROR: syntax error at or near "analyze"
LINE 1: explain (buffers true) analyze select * from tab1...
Same for COSTS.
Does any of our experts use these options? If yes, please tell me how.
Try putting the ANALYZE inside the parentheses..
eg
EXPLAIN (buffers true, analyze) select * from tab1;
--
Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
