Re: index prefetching

Andres Freund <andres@anarazel.de>

From: Andres Freund <andres@anarazel.de>

To: Peter Geoghegan <pg@bowt.ie>

Cc: Tomas Vondra <tomas@vondra.me>, Thomas Munro <thomas.munro@gmail.com>, Nazir Bilal Yavuz <byavuz81@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Georgios <gkokolatos@protonmail.com>, Konstantin Knizhnik <knizhnik@garret.ru>, Dilip Kumar <dilipbalaut@gmail.com>

Date: 2025-08-15T19:38:31Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

aio: io_uring: Trigger async processing for large IOs
- a9ee66881744 19 (unreleased) landed
read stream: Split decision about look ahead for AIO and combining
- 8ca147d582a5 19 (unreleased) landed
read_stream: Only increase read-ahead distance when waiting for IO
- f63ca3379025 19 (unreleased) landed
read_stream: Prevent distance from decaying too quickly
- 6e36930f9aaf 19 (unreleased) landed
Reduce ExecSeqScan* code size using pg_assume()
- b227b0bb4e03 19 (unreleased) cited
Fix rare bug in read_stream.c's split IO handling.
- b421223172a2 19 (unreleased) cited
Fix multiranges to behave more like dependent types.
- 3e8235ba4f9c 17.0 cited
Add EXPLAIN (MEMORY) to report planner memory consumption
- 5de890e3610d 17.0 cited
Optimize nbtree backward scan boundary cases.
- c9c0589fda0e 17.0 cited
Increment xactCompletionCount during subtransaction abort.
- 90c885cdab8b 14.0 cited
Add nbtree Valgrind buffer lock checks.
- 4a70f829d86c 14.0 cited
Add nbtree high key "continuescan" optimization.
- 29b64d1de7c7 12.0 cited
Reduce pinning and buffer content locking for btree scans.
- 2ed5b87f96d4 9.5.0 cited
Teach btree to handle ScalarArrayOpExpr quals natively.
- 9e8da0f75731 9.2.0 cited

Hi,

On 2025-08-15 15:31:47 -0400, Peter Geoghegan wrote:
> On Fri, Aug 15, 2025 at 3:28 PM Andres Freund <andres@anarazel.de> wrote:
> > >I'm not worried about it. Andres' "not waiting for already-in-progress
> > >IO" patch was clearly just a prototype. Just thought it was worth
> > >noting here.
> >
> > Are you confident in that? Because the patch should be extremely cheap in that case.
> 
> I'm pretty confident.
> 
> > What precisely were you testing?
> 
> I'm just running my usual generic pgbench SELECT script, with my usual
> settings (so no direct I/O, but with iouring).

I see absolutely no effect of the patch with shared_buffers=1GB and a
read-only scale 200 pgbench at 40 clients. What data sizes, shared buffers
etc. were you testing?

Greetings,

Andres Freund