Horton

Re: scalability bottlenecks with (many) partitions (and more)

Tom Lane <tgl@sss.pgh.pa.us>

View thread
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas@vondra.me>
Cc: Jakub Wartak <jakub.wartak@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>
Date: 2024-09-22T23:06:46Z
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. Make FP_LOCK_SLOTS_PER_BACKEND look like a function

  2. Fix asserts in fast-path locking code

  3. Increase the number of fast-path lock slots

Tomas Vondra <tomas@vondra.me> writes:
> On 9/22/24 17:45, Tom Lane wrote:
>> #define FAST_PATH_GROUP(index)	\
>> -	(AssertMacro(((index) >= 0) && ((index) < FP_LOCK_SLOTS_PER_BACKEND)), \
>> +	(AssertMacro((uint32) (index) < FP_LOCK_SLOTS_PER_BACKEND), \
>> ((index) / FP_LOCK_SLOTS_PER_GROUP))

> For the (x >= 0) asserts, doing it this way relies on negative values
> wrapping to large positive ones, correct? AFAIK it's guaranteed to be a
> very large value, so it can't accidentally be less than the slot count.

Right, any negative value would wrap to something more than
INT32_MAX.

			regards, tom lane