From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Rodrigo Rosenfeld Rosas <rr.rosas@gmail.com>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Extremely slow DELETE with cascade foreign keys
Date: Tue, 5 Dec 2017 13:43:28 -0300
Message-ID: <20171205164328.6t4w3abfpzp54y2y@alvherre.pgsql> (raw)
In-Reply-To: <8f569ed9-fde9-1fe7-4beb-01945009e040@gmail.com>
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.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-performance@postgresql.org
Cc: 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: <20171205164328.6t4w3abfpzp54y2y@alvherre.pgsql>
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