Re: index prefetching
Peter Geoghegan <pg@bowt.ie>
From: "Peter Geoghegan" <pg@bowt.ie>
To: "Peter Geoghegan" <pg@bowt.ie>, "Andres Freund" <andres@anarazel.de>
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: 2025-08-14T19:30:16Z
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
On Thu Aug 14, 2025 at 3:15 PM EDT, Peter Geoghegan wrote: > On Thu, Aug 14, 2025 at 2:53 PM Andres Freund <andres@anarazel.de> wrote: >> I think this is just an indicator of being IO bound. > > Then why does the exact same pair of runs show "I/O Timings: shared > read=194.629" for the sequential table backwards scan (with total > execution time 1132.360 ms), versus "I/O Timings: shared read=352.88" > (with total execution time 697.681 ms) for the random table backwards > scan? Is there any particular significance to the invalid op reports I also see in the same log files? $ cat sequential.txt | grep invalid | head 2025-08-14 14:35:03.278 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 2, ref_gen: 1, cycle 1 2025-08-14 14:35:03.278 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 3, ref_gen: 2, cycle 1 2025-08-14 14:35:03.278 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 4, ref_gen: 3, cycle 1 2025-08-14 14:35:03.278 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 5, ref_gen: 4, cycle 1 2025-08-14 14:35:03.278 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 6, ref_gen: 5, cycle 1 2025-08-14 14:35:03.278 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 7, ref_gen: 6, cycle 1 2025-08-14 14:35:03.279 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 8, ref_gen: 7, cycle 1 2025-08-14 14:35:03.279 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 9, ref_gen: 8, cycle 1 2025-08-14 14:35:03.279 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 10, ref_gen: 9, cycle 1 2025-08-14 14:35:03.279 EDT [2516983][client backend] [[unknown]][0/1:0] DEBUG: 00000: io 0 |op invalid|target invalid|state IDLE : wait_one io_gen: 11, ref_gen: 10, cycle 1 $ cat sequential.txt | grep invalid | wc -l 5733 $ cat random.txt | grep invalid | wc -l 2206 -- Peter Geoghegan