Re: pg_trgm comparison bug on cross-architecture replication due to different char implementation

On Mon, Sep 9, 2024 at 4:42 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> writes:
> > When do we set the byte on the primary server? If it's the first time
> > to use the GIN index, secondary servers would have to wait for the
> > primary to use the GIN index, which could be an unpredictable time or
> > it may never come depending on index usages. Probably we can make
> > pg_upgrade set the byte in the meta page of GIN indexes that use the
> > gin_trgm_ops.
>
> Hmm, perhaps. That plus set-it-during-index-create would remove the
> need for dynamic update like I suggested. So very roughly the amount
> of complexity would balance out.

Yes, I think your set-it-during-index-create would be necessary.

> Do you have an idea for how we'd get
> this to happen during pg_upgrade, exactly?

What I was thinking is that we have "pg_dump --binary-upgrade" emit a
function call, say "SELECT binary_upgrade_update_gin_meta_page()" for
each GIN index, and the meta pages are updated when restoring the
schemas.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com