On Tue, Aug 08, 2023 at 03:59:54PM -0700, Andres Freund wrote: > On 2023-08-08 08:54:10 +0900, Michael Paquier wrote: >> - WaitEventExtensionShmemInit() should gain a dshash_create(), to make >> sure that the shared table is around, and we are going to have a >> reference to it in WaitEventExtensionCounterData, saved from >> dshash_get_hash_table_handle(). > > I'm not even sure it's worth using dshash here. Why don't we just create a > decently sized dynahash (say 128 enties) in shared memory? We overallocate > shared memory by enough that there's a lot of headroom for further entries, in > the rare cases they're needed.
The question here would be how many slots the most popular extensions actually need, but that could always be sized up based on the feedback. >> We are going to need a fixed size for these custom strings, but perhaps a >> hard limit of 256 characters for each entry of the hash table is more than >> enough for most users? > > I'd just use NAMEDATALEN. Both suggestions WFM. -- Michael
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