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From: Ron <ronljohnsonjr@gmail.com>
To: pgsql-general@lists.postgresql.org
Subject: Re: explain analyze cost
Date: Wed, 12 Dec 2018 16:45:43 -0600
Message-ID: <01ad39ba-d283-875f-6121-76141a6a4874@gmail.com> (raw)
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On 12/12/2018 04:37 PM, Ravi Krishna wrote:
> I am running explain analyze cost on a SQL which reads from two large 
> tables (122mil and 37 mil).  The query is an UPDATE SQL where we use 
> derives table in the from clause and then join it back to the table being 
> updated.
>
> The explain analyze cost itself is taking forever to run. It is running 
> for the last 1 hr. Does that actually run the SQL to find out the impact 
> of I/O (as indicated in COSTS).

Yes.

https://www.postgresql.org/docs/9.6/sql-explain.html

"The ANALYZE option causes the statement to be actually executed, not only 
planned."

> If not, what can cause it to run this slow.
>

-- 
Angular momentum makes the world go 'round.

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