From: | "Drouvot, Bertrand" <bdrouvot(at)amazon(dot)com> |
---|---|
To: | Justin Pryzby <pryzby(at)telsasoft(dot)com>, <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: ALTER TABLE uses a bistate but not for toast tables |
Date: | 2022-09-07 08:48:39 |
Message-ID: | fa936b64-f228-dd58-c0bd-44f19d43d5f6@amazon.com |
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Lists: | pgsql-hackers |
Hi,
On 6/22/22 4:38 PM, Justin Pryzby wrote:
> ATRewriteTable() calls table_tuple_insert() with a bistate, to avoid clobbering
> and polluting the buffers.
>
> But heap_insert() then calls
> heap_prepare_insert() >
> heap_toast_insert_or_update >
> toast_tuple_externalize >
> toast_save_datum >
> heap_insert(toastrel, toasttup, mycid, options, NULL /* without bistate:( */);
Good catch!
> I came up with this patch.
+ /* Release pin after main table, before switching to write to
toast table */
+ if (bistate)
+ ReleaseBulkInsertStatePin(bistate);
I'm not sure we should release and reuse here the bistate of the main
table: it looks like that with the patch ReadBufferBI() on the main
relation wont have the desired block already pinned (then would need to
perform a read).
What do you think about creating earlier a new dedicated bistate for the
toast table?
+ if (bistate)
+ {
+ table_finish_bulk_insert(toastrel, options); // XXX
I think it's too early, as it looks to me that at this stage we may have
not finished the whole bulk insert yet.
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services:https://aws.amazon.com
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