| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Tomas Vondra <tomas(at)vondra(dot)me> |
| Cc: | Jakub Wartak <jakub(dot)wartak(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: scalability bottlenecks with (many) partitions (and more) |
| Date: | 2024-09-22 23:06:46 |
| Message-ID: | 2942266.1727046406@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Tomas Vondra <tomas(at)vondra(dot)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
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