From: | Clailson <clailson(dot)dba(at)gmail(dot)com> |
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To: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Optimization inner join |
Date: | 2017-01-19 10:08:47 |
Message-ID: | 7ad1128e-7fdb-9976-823c-d4abdf554fa2@gmail.com |
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Lists: | pgsql-performance |
Hi,
Is there something in the roadmap to optimize the inner join?
I've this situation above. Table b has 400 rows with null in the column b.
explain analyze select * from a inner join b on (b.b = a.a);
"Merge Join (cost=0.55..65.30 rows=599 width=16) (actual time=0.030..1.173 rows=599 loops=1)"
" Merge Cond: (a.a = b.b)"
" -> Index Scan using a_pkey on a (cost=0.28..35.27 rows=1000 width=8) (actual time=0.014..0.364 rows=1000 loops=1)"
" -> Index Scan using in01 on b (cost=0.28..33.27 rows=1000 width=8) (actual time=0.012..0.249 rows=600 loops=1)"
"Total runtime: 1.248 ms"
My question is: Why the planner isn't removing the null rows during the
scan of table b?
--
Clailson Soares Dinízio de Almeida
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