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* pgsql: Reduce scope of heap vacuum per_buffer_data
@ 2025-02-18 14:30 Melanie Plageman <melanieplageman@gmail.com>
2025-02-18 16:24 ` Re: pgsql: Reduce scope of heap vacuum per_buffer_data Melanie Plageman <melanieplageman@gmail.com>
0 siblings, 1 reply; 2+ messages in thread
From: Melanie Plageman @ 2025-02-18 14:30 UTC (permalink / raw)
To: pgsql-committers@lists.postgresql.org
Reduce scope of heap vacuum per_buffer_data
Move lazy_scan_heap()'s per_buffer_data variable into a tighter scope.
In lazy_scan_heap()'s phase I heap vacuuming, the read stream API
returns a pointer to the next block number to vacuum. As long as
read_stream_next_buffer() returns a valid buffer, per_buffer_data should
always be valid.
Move per_buffer_data into a tighter scope and make sure it is reset to
NULL on each iteration so that we get a core dump instead of bogus data
from a previous block if something goes wrong in the read stream API.
Suggested-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/626104.1739729538%40sss.pgh.pa.us
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/c623e8593ec4ee6987f3cd9350ced7caf8526ed2
Modified Files
--------------
src/backend/access/heap/vacuumlazy.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: pgsql: Reduce scope of heap vacuum per_buffer_data
2025-02-18 14:30 pgsql: Reduce scope of heap vacuum per_buffer_data Melanie Plageman <melanieplageman@gmail.com>
@ 2025-02-18 16:24 ` Melanie Plageman <melanieplageman@gmail.com>
0 siblings, 0 replies; 2+ messages in thread
From: Melanie Plageman @ 2025-02-18 16:24 UTC (permalink / raw)
To: pgsql-committers@lists.postgresql.org
On Tue, Feb 18, 2025 at 9:30 AM Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> Reduce scope of heap vacuum per_buffer_data
>
> Move lazy_scan_heap()'s per_buffer_data variable into a tighter scope.
> In lazy_scan_heap()'s phase I heap vacuuming, the read stream API
> returns a pointer to the next block number to vacuum. As long as
> read_stream_next_buffer() returns a valid buffer, per_buffer_data should
> always be valid.
Realized I forgot an important word in the commit message.
per_buffer_data doesn't point to the block number. It points to info
about the next block. Commit message should say "the read stream API
returns a pointer to information about the next block to vacuum". Oh
well... There is nothing I can do now.
- Melanie
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2025-02-18 14:30 pgsql: Reduce scope of heap vacuum per_buffer_data Melanie Plageman <melanieplageman@gmail.com>
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