From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Rodrigo Rosenfeld Rosas <rr.rosas@gmail.com>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Extremely slow DELETE with cascade foreign keys
Date: Tue, 05 Dec 2017 12:25:26 -0500
Message-ID: <10850.1512494726@sss.pgh.pa.us> (raw)
In-Reply-To: <20171205164328.6t4w3abfpzp54y2y@alvherre.pgsql>
References: <20171205164328.6t4w3abfpzp54y2y@alvherre.pgsql>
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> Rodrigo Rosenfeld Rosas wrote:
>> explain analyze delete from field_values where transaction_id=226;
>> QUERY PLAN
>> ---------------------------------------------------------------------------------------------------------------------------------------------------------------
>> Delete on field_values (cost=0.43..257.93 rows=481 width=6) (actual
>> time=367375.805..367375.805 rows=0 loops=1)
>> -> Index Scan using index_field_values_on_transaction_id on
>> field_values (cost=0.43..257.93 rows=481 width=6) (actual time=0.223..4.216
>> rows=651 loops=1)
>> Index Cond: (transaction_id = 226)
>> Planning time: 0.234 ms
>> Execution time: 367375.882 ms
>> (5 registros)
>>
>> Time: 367377,085 ms (06:07,377)
> Normally this is because you lack indexes on the referencing columns, so
> the query that scans the table to find the referencing rows is a
> seqscan.
Actually though ... the weird thing about this is that I'd expect to
see a separate line in the EXPLAIN output for time spent in the FK
trigger. Where'd that go?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, alvherre@alvh.no-ip.org, rr.rosas@gmail.com, pgsql-performance@lists.postgresql.org
Subject: Re: Extremely slow DELETE with cascade foreign keys
In-Reply-To: <10850.1512494726@sss.pgh.pa.us>
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