Re: [HACKERS] Hash Functions

Поиск
Список
Период
Сортировка
От Tom Lane
Тема Re: [HACKERS] Hash Functions
Дата
Msg-id 28148.1502901501@sss.pgh.pa.us
обсуждение исходный текст
Ответ на Re: [HACKERS] Hash Functions  (Robert Haas <robertmhaas@gmail.com>)
Ответы Re: [HACKERS] Hash Functions  (Robert Haas <robertmhaas@gmail.com>)
Re: [HACKERS] Hash Functions  (Robert Haas <robertmhaas@gmail.com>)
Список pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> After some further thought, I propose the following approach to the
> issues raised on this thread:

> 1. Allow hash functions to have a second, optional support function,
> similar to what we did for btree opclasses in
> c6e3ac11b60ac4a8942ab964252d51c1c0bd8845.  The second function will
> have a signature of (opclass_datatype, int64) and should return int64.
> The int64 argument is a salt.  When the salt is 0, the low 32 bits of
> the return value should match what the existing hash support function
> returns.  Otherwise, the salt should be used to perturb the hash
> calculation.

+1

> 2. Introduce a new hash opfamilies here which are more faster, more
> portable, and/or better in other ways than the ones we have today.

This part seems, uh, under-defined and/or over-ambitious and/or unrelated
to the problem at hand.  What are the concrete goals?
        regards, tom lane



В списке pgsql-hackers по дате отправления:

Предыдущее
От: Tom Lane
Дата:
Сообщение: [HACKERS] Garbled comment in postgresGetForeignJoinPaths
Следующее
От: Tom Lane
Дата:
Сообщение: Re: [HACKERS] [COMMITTERS] pgsql: Simplify plpgsql's check for simple expressions.