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* Improving SQL performance
@ 2007-01-11 18:17 Carlos H. Reimer <carlos.reimer@opendb.com.br>
2007-01-11 18:28 ` Re: Improving SQL performance Russell Smith <mr-russ@pws.com.au>
2007-01-11 18:31 ` Re: Improving SQL performance Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 2 replies; 3+ messages in thread
From: Carlos H. Reimer @ 2007-01-11 18:17 UTC (permalink / raw)
To: pgsql-performance
Hi,
I know that the problem with the following SQL is the "LOG.CODCEP =
ENDE.CODCEP||CODLOG" condition, but what can I
do to improve the performance?
Is there a type of index that could help or is there another way to build
this SQL?
Thank you in advance!
explain analyze
SELECT ENDE.* , DEND.DESEND, DEND.USOEND, DEND.DUPEND,
to_char('F') as NOVO,
LOG.TIPLOG
FROM TT_END ENDE LEFT OUTER JOIN TD_END DEND ON DEND.CODTAB =
ENDE.TIPEND
LEFT OUTER JOIN TT_LOG LOG ON LOG.CODCEP =
ENDE.CODCEP||CODLOG
WHERE ENDE.FILCLI = '001'
AND ENDE.CODCLI = ' 19475';
QUERY PLAN
----------------------------------------------------------------------------
------------------------------------------------------
Nested Loop Left Join (cost=0.00..25366.84 rows=1259 width=417) (actual
time=1901.499..1901.529 rows=1 loops=1)
Join Filter: (("inner".codcep)::text = (("outer".codcep)::text ||
("outer".codlog)::text))
-> Nested Loop Left Join (cost=0.00..4.91 rows=1 width=412) (actual
time=0.117..0.144 rows=1 loops=1)
Join Filter: ("inner".codtab = "outer".tipend)
-> Index Scan using pk_end on tt_end ende (cost=0.00..3.87 rows=1
width=388) (actual time=0.066..0.078 rows=1 loops=1)
Index Cond: ((filcli = '001'::bpchar) AND (codcli = '
19475'::bpchar))
-> Seq Scan on td_end dend (cost=0.00..1.02 rows=2 width=33)
(actual time=0.012..0.018 rows=2 loops=1)
-> Seq Scan on tt_log log (cost=0.00..12254.24 rows=582424 width=17)
(actual time=0.013..582.521 rows=582424 loops=1)
Total runtime: 1901.769 ms
(9 rows)
\d tt_log
Table "TOTALL.tt_log"
Column | Type | Modifiers
--------+------------------------+-----------
codbai | numeric(5,0) | not null
nomlog | character varying(55) | not null
codcep | character(8) | not null
\d tt_end
Table "TOTALL.tt_end"
Column | Type | Modifiers
--------+-----------------------+-----------------------------------------
...
...
...
codlog | character(3) |
...
...
...
codcep | character(5) |
...
...
Reimer
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Improving SQL performance
2007-01-11 18:17 Improving SQL performance Carlos H. Reimer <carlos.reimer@opendb.com.br>
@ 2007-01-11 18:28 ` Russell Smith <mr-russ@pws.com.au>
1 sibling, 0 replies; 3+ messages in thread
From: Russell Smith @ 2007-01-11 18:28 UTC (permalink / raw)
To: carlos.reimer@opendb.com.br; +Cc: pgsql-performance
Carlos H. Reimer wrote:
> Hi,
>
> I know that the problem with the following SQL is the "LOG.CODCEP =
> ENDE.CODCEP||CODLOG" condition, but what can I
> do to improve the performance?
>
I wouldn't say it's the join condition. There is a nested loop join on
500k+ rows.
Is it possible to put an index on LOG.CODCEP?
That might give you a better plan, as you only have 1 row in the left of
the join. so index scan would be preferable.
Regards
Russell Smith
> Is there a type of index that could help or is there another way to
> build this SQL?
>
> Thank you in advance!
>
> explain analyze
> SELECT ENDE.* , DEND.DESEND, DEND.USOEND, DEND.DUPEND,
> to_char('F') as NOVO,
> LOG.TIPLOG
> FROM TT_END ENDE LEFT OUTER JOIN TD_END DEND ON DEND.CODTAB
> = ENDE.TIPEND
> LEFT OUTER JOIN TT_LOG LOG ON LOG.CODCEP =
> ENDE.CODCEP||CODLOG
> WHERE ENDE.FILCLI = '001'
> AND ENDE.CODCLI = ' 19475';
>
>
> QUERY
> PLAN
> ----------------------------------------------------------------------------------------------------------------------------------
> Nested Loop Left Join (cost=0.00..25366.84 rows=1259 width=417)
> (actual time=1901.499..1901.529 rows=1 loops=1)
> Join Filter: (("inner".codcep)::text = (("outer".codcep)::text ||
> ("outer".codlog)::text))
> -> Nested Loop Left Join (cost=0.00..4.91 rows=1 width=412)
> (actual time=0.117..0.144 rows=1 loops=1)
> Join Filter: ("inner".codtab = "outer".tipend)
> -> Index Scan using pk_end on tt_end ende (cost=0.00..3.87
> rows=1 width=388) (actual time=0.066..0.078 rows=1 loops=1)
> Index Cond: ((filcli = '001'::bpchar) AND (codcli = '
> 19475'::bpchar))
> -> Seq Scan on td_end dend (cost=0.00..1.02 rows=2
> width=33) (actual time=0.012..0.018 rows=2 loops=1)
> -> Seq Scan on tt_log log (cost=0.00..12254.24 rows=582424
> width=17) (actual time=0.013..582.521 rows=582424 loops=1)
> Total runtime: 1901.769 ms
> (9 rows)
>
> \d tt_log
> Table "TOTALL.tt_log"
> Column | Type | Modifiers
> --------+------------------------+-----------
> codbai | numeric(5,0) | not null
> nomlog | character varying(55) | not null
> codcep | character(8) | not null
>
> \d tt_end
> Table "TOTALL.tt_end"
> Column | Type | Modifiers
> --------+-----------------------+-----------------------------------------
> ...
> ...
> ...
> codlog | character(3) |
> ...
> ...
> ...
> codcep | character(5) |
> ...
> ...
>
> Reimer
>
>
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Improving SQL performance
2007-01-11 18:17 Improving SQL performance Carlos H. Reimer <carlos.reimer@opendb.com.br>
@ 2007-01-11 18:31 ` Tom Lane <tgl@sss.pgh.pa.us>
1 sibling, 0 replies; 3+ messages in thread
From: Tom Lane @ 2007-01-11 18:31 UTC (permalink / raw)
To: carlos.reimer@opendb.com.br; +Cc: pgsql-performance
"Carlos H. Reimer" <carlos.reimer@opendb.com.br> writes:
> I know that the problem with the following SQL is the "LOG.CODCEP =
> ENDE.CODCEP||CODLOG" condition, but what can I
> do to improve the performance?
Seems the problem is not using an index for tt_log. Do you have an
index on tt_log.codcep? If so, maybe you need to cast the result of
the concatenation to char(8) to get it to use the index.
regards, tom lane
^ permalink raw reply [nested|flat] 3+ messages in thread
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2007-01-11 18:17 Improving SQL performance Carlos H. Reimer <carlos.reimer@opendb.com.br>
2007-01-11 18:28 ` Russell Smith <mr-russ@pws.com.au>
2007-01-11 18:31 ` Tom Lane <tgl@sss.pgh.pa.us>
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