| From: | Jim Mlodgenski <jimmy76(at)gmail(dot)com> |
|---|---|
| To: | Steve Pritchard <steve(dot)pritchard(at)bto(dot)org> |
| Cc: | Pgsql Performance <pgsql-performance(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Want function to be called only once in query |
| Date: | 2021-09-16 10:56:05 |
| Message-ID: | CAB_5SRee1qAo9U3smCMxezHWi-w+1=1sHk_q2Hcnt5LbgxO9jA@mail.gmail.com |
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| Lists: | pgsql-performance |
On Thu, Sep 16, 2021 at 4:51 AM Steve Pritchard <steve(dot)pritchard(at)bto(dot)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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