Re: explain analyze cost

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.
>

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