From: Arne Roland <A.Roland@index.de>
To: pgsql-hackers@lists.postgresql.org <pgsql-hackers@lists.postgresql.org>
Subject: Partial join
Date: Thu, 1 Aug 2019 08:07:25 +0000
Message-ID: <dd01626a46a342f7b1d811cf38fcebe6@index.de> (raw)
In-Reply-To: <9dc03e949e9b4327a0d074da9ab44318@index.de>
References: <9dc03e949e9b4327a0d074da9ab44318@index.de>
Hello,
I attached one example of a partitioned table with multi column partition key. I also attached the output.
Disabling the hash_join is not really necessary, it just shows the more drastic result in the case of low work_mem.
Comparing the first and the second query I was surprised to see that SET enable_partitionwise_join could cause the costs to go up. Shouldn't the paths of the first query be generated as well?
The third query seems to have a different issue. That one is close to my original performance problem. It looks to me like the push down of the sl condition stops the optimizer considering a partial join.
If so would it be sane to keep a copy of the original quals to make the partial join possible? Do you have better ideas?
Regards
Arne
Attachments:
[application/sql] querys.sql (2.3K, ../dd01626a46a342f7b1d811cf38fcebe6@index.de/3-querys.sql)
download
[application/sql] explain_analyze.sql (7.7K, ../dd01626a46a342f7b1d811cf38fcebe6@index.de/4-explain_analyze.sql)
download
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To: pgsql-performance@postgresql.org
Cc: A.Roland@index.de, pgsql-hackers@lists.postgresql.org
Subject: Re: Partial join
In-Reply-To: <dd01626a46a342f7b1d811cf38fcebe6@index.de>
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