Re: update from select - Mailing list pgsql-sql

Yes, both have varchar(50).

Query:

UPDATE owner SET picturemedium = dvds.picturemedium, title = dvds.title,
titleOrder = dvds.title, releasedate = CAST(dvds.releasedate AS date) FROM
(SELECT DISTINCTdetail_dvd.asin,detail_dvd.picturemedium,detail_dvd.title,detail_dvd.releasedateFROM detail_dvd WHERE
releasedateIS NOT NULL AND releasedate <> '' AND 
(length(releasedate) = 10 OR length(releasedate) = 23)
)
AS dvds WHERE owner.asin = dvds.asin;

***********************************************************
EXPLAIN ANALYZE:

Hash Join  (cost=10827.45..25950.05 rows=4906 width=1191) (actual
time=586.251..2852.691 rows=111306 loops=1)
"  Hash Cond: ((""owner"".asin)::text = (dvds.asin)::text)"
"  ->  Seq Scan on ""owner""  (cost=0.00..14148.98 rows=230198 width=101)
(actual time=0.050..968.028 rows=230198 loops=1)" ->  Hash  (cost=10825.02..10825.02 rows=194 width=1208) (actual
time=584.463..584.463 rows=19489 loops=1)       ->  Subquery Scan dvds  (cost=10820.66..10825.02 rows=194
width=1208) (actual time=435.005..545.213 rows=19489 loops=1)             ->  Unique  (cost=10820.66..10823.08 rows=194
width=110)
(actual time=435.002..520.725 rows=19489 loops=1)                   ->  Sort  (cost=10820.66..10821.14 rows=194
width=110)
(actual time=434.998..491.487 rows=19489 loops=1)                         Sort Key: asin, picturemedium, title,
releasedate                        ->  Seq Scan on detail_dvd  (cost=0.00..10813.29 
rows=194 width=110) (actual time=0.042..166.493 rows=19489 loops=1)                               Filter: ((releasedate
ISNOT NULL) AND 
((releasedate)::text <> ''::text) AND ((length((releasedate)::text) = 10) OR
(length((releasedate)::text) = 23)))
Total runtime: 633548.404 ms
***********************************************************

He is not using the index on asin? When I reduce the SELECT to 100, he is
using the index! perhaps to many rows are affected?
The DISTINCT in the SELECT is not really necessary. It's just for security
reasons. And I did check it. It's unique! But as I said before. The SELECT
takes around 1 second! I have 13 indices on the UPDATE table. So I did
delete the one I don’t need for this query... Now I have 3 left! And it
takes around 2 Minutes! But that’s also a problem, because I need the
Indexes again! Is it possible to set the way, Postgres is building the
indices? Or is the only way deleting the indeces before UPDATE and then
creating them again?


I also tried this query (PostgreSQL's extension):

UPDATE owner SET picturemedium = detail_dvd.picturemedium, title =
detail_dvd.title, titleOrder = detail_dvd.title, releasedate =
CAST(detail_dvd.releasedate AS date)
FROM detail_dvd
WHERE owner.asin = detail_dvd.asin
AND detail_dvd.releasedate IS NOT NULL
AND detail_dvd.releasedate <> ''
AND (length(detail_dvd.releasedate) = 10 OR length(detail_dvd.releasedate) =
23);

But its also to slow:

***********************************************************
EXPLAIN ANALYZE:

Nested Loop  (cost=0.00..28175.75 rows=2006 width=195) (actual
time=0.138..127695.132 rows=111306 loops=1) ->  Seq Scan on detail_dvd  (cost=0.00..10813.29 rows=194 width=110)
(actual time=0.035..615.511 rows=19489 loops=1)       Filter: ((releasedate IS NOT NULL) AND ((releasedate)::text <>
''::text) AND ((length((releasedate)::text) = 10) OR
(length((releasedate)::text) = 23)))
"  ->  Index Scan using ""iidx-owner-asin"" on ""owner""  (cost=0.00..89.04
rows=26 width=99) (actual time=2.848..6.485 rows=6 loops=19489)"
"        Index Cond: ((""owner"".asin)::text = (detail_dvd.asin)::text)"
Total runtime: 1039998.325 ms
***********************************************************


Thaks for helping!! Bye the way, we are changing our system from MSSQL2000
to Postgres :-)!

Regards
Reto


-----Ursprüngliche Nachricht-----
Von: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org]
Im Auftrag von A. Kretschmer
Gesendet: Montag, 29. Oktober 2007 11:45
An: pgsql-sql@postgresql.org
Betreff: Re: [SQL] update from select

am  Mon, dem 29.10.2007, um 10:18:38 +0100 mailte dev@kbsolutions.ch
folgendes:
>
> WHERE table1.column1 = temp_table.column1;

table1.column1 and temp_table.column1 have the same type?

>
>
>
> The select by it?s own takes around 1 second. The Update is around 120?000
> rows. I got an index on column1. The whole query needs around 16 minutes.

Show us the EXPLAIN ANALYSE - result.


Andreas
--
Andreas Kretschmer
Kontakt:  Heynitz: 035242/47150,   D1: 0160/7141639 (mehr: -> Header)
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