Re: :Posgres - performance problem - Mailing list pgsql-general

On Wed, Mar 25, 2015 at 4:19 AM, ginkgo36 <ginkgo56@gmail.com> wrote:
> Hi all,
> I have 1 table have:
> - 417 columns
> - 600.000 rows data
> - 34 indexs
>
> when i use query on this table, it so long. ex:
>
> update master_items set
> temp1 = '' where temp1 <> '' --Query returned successfully: 435214 rows
> affected, 1016137 ms execution time.
>
> alter table master_items add "TYPE-DE" varchar default ''
> -- Query returned successfully with no result in 1211019 ms.
>
> update master_items set "feedback_to_de" = 'Yes'
> --Query returned successfully: 591268 rows affected, 1589335 ms execution
> time.
>
> Can you help me find any way to increase performance?
>
> Thanks all

I am not any kind of a performance expert. But the first thing that I
would try is an EXPLAIN. If you're using the psql line command, I'd do
something like:

BEGIN; -- BEGIN TRANSACTION
EXPLAIN (ANALYZE, TIMING) UPDATE master_items SET temp1 = "where temp1 <>";
ROLLBACK;

I'd put the EXPLAIN in a transaction that I roll back so that I
wouldn't actually update anything permanently . Also, doing a simple
ANALYZE on the table might help some. I'm not sure.

ANALYZE master_items;

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