Horton

Re: index prefetching

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Tomas Vondra <tomas@vondra.me>
Cc: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Georgios <gkokolatos@protonmail.com>, Thomas Munro <thomas.munro@gmail.com>, Konstantin Knizhnik <knizhnik@garret.ru>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2025-07-16T14:29:36Z
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 →

  1. aio: io_uring: Trigger async processing for large IOs

  2. read stream: Split decision about look ahead for AIO and combining

  3. read_stream: Only increase read-ahead distance when waiting for IO

  4. read_stream: Prevent distance from decaying too quickly

  5. Reduce ExecSeqScan* code size using pg_assume()

  6. Fix rare bug in read_stream.c's split IO handling.

  7. Fix multiranges to behave more like dependent types.

  8. Add EXPLAIN (MEMORY) to report planner memory consumption

  9. Optimize nbtree backward scan boundary cases.

  10. Increment xactCompletionCount during subtransaction abort.

  11. Add nbtree Valgrind buffer lock checks.

  12. Add nbtree high key "continuescan" optimization.

  13. Reduce pinning and buffer content locking for btree scans.

  14. Teach btree to handle ScalarArrayOpExpr quals natively.

On Wed, Jul 16, 2025 at 10:20 AM Tomas Vondra <tomas@vondra.me> wrote:
> The read stream can only return blocks generated by the "next" callback.
> When we return the block for the last item on a leaf page, we can only
> return "InvalidBlockNumber" which means "no more blocks in the stream".
> And once we advance to the next leaf, we say "hey, there's more blocks".
> Which is what read_stream_reset() does.
>
> It's a bit like what rescan does.

That sounds weird.

> In an ideal world we'd have a function that'd "pause" the stream,
> without resetting the distance etc. But we don't have that, and the
> reset thing was suggested to me as a workaround.

Does the "complex" patch require a similar workaround? Why or why not?

-- 
Peter Geoghegan