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From: Laurenz Albe <[email protected]>
To: James Pang <[email protected]>
To: [email protected]
Subject: Re: cached plan must not change result type
Date: Fri, 29 Mar 2024 09:40:14 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAHgTRfcg2jGnjSqq1NVuMDtCjRU3aOXWrhXn1L=92Ka_Ug6euw@mail.gmail.com>
References: <CAHgTRfcg2jGnjSqq1NVuMDtCjRU3aOXWrhXn1L=92Ka_Ug6euw@mail.gmail.com>

On Fri, 2024-03-29 at 10:05 +0800, James Pang wrote:
> PGV14, client use PGJDBC driver and prepared statements, when a table
> "alter table alter column type ..." changes done, a lot of JDBC clients
> got this error "cached plan must not change result type".  when a JDBC
> client got this error first time after the DDL schema change, JDBC driver
> will clear this caching-plan and following same SQL statement got parsing
> again and new cached plan right?

Not sure; what do you observe?
Anyway, this is a known problem:
https://jdbc.postgresql.org/documentation/server-prepare/#ddl

> How to avoid this issue when DDL schema changes ?

Don't use server-side prepared statements:
https://jdbc.postgresql.org/documentation/server-prepare/#deactivation
You'll lose some performance though.

Questions like this had better be asked on the pgsql-jdbc list.

Yours,
Laurenz Albe





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