Re: Want function to be called only once in query

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От Steve Pritchard
Тема Re: Want function to be called only once in query
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Msg-id CAF7Aqmz_go1rOEBAm6Wz87zXd82TxEpRrLd5_RxVaaKkv2ALog@mail.gmail.com
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Ответ на Re: Want function to be called only once in query  (Jim Mlodgenski <jimmy76@gmail.com>)
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> Add the MATERIALIZED keyword to the WITH statement

Many thanks Jim, that's just what I needed - that does the trick.

It's hard to keep abreast of these SQL changes. Thank goodness for mailing lists!

Steve

On Thu, 16 Sept 2021 at 11:56, Jim Mlodgenski <jimmy76@gmail.com> wrote:
On Thu, Sep 16, 2021 at 4:51 AM Steve Pritchard <steve.pritchard@bto.org> wrote:
>
> I have a PL/pgSQL function that I want to call within a query, but the function is fairly expensive to execute so I only want it executed once within the query. However the planner seems to reorganize my query so that it calls the function for every row.
>
> We were previously on Pg 9.6 and this wasn't a problem then. But now that we have upgraded to Pg 13, the behaviour has changed.
>

The behavior for planning a CTE changed in PG12.

> There must be a "proper" way to get the planner to call a function only once.
>
Add the MATERIALIZED keyword to the WITH statement


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Steve Pritchard
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