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
