Re: [HACKERS] Hash Functions - Mailing list pgsql-hackers

From Jeff Davis
Subject Re: [HACKERS] Hash Functions
Date
Msg-id CAMp0ubey3BApQ8oPp1GcJt-Q1OtAsXBdwLNtz3FVaQ5ohvAjgg@mail.gmail.com
Whole thread Raw
In response to Re: [HACKERS] Hash Functions  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: [HACKERS] Hash Functions  (Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>)
Re: [HACKERS] Hash Functions  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Tuesday, May 16, 2017, Robert Haas <robertmhaas@gmail.com> wrote:
> I don't really find this a very practical design.  If the table
> partitions are spread across different relfilenodes, then those
> relfilenodes have to have separate pg_class entries and separate
> indexes, and those indexes also need to have separate pg_class
> entries.  Otherwise, nothing works.  And if they do have separate
> pg_class entries, then the partitions have to have their own names,
> and likewise for their indexes, and a dump-and-reload has to preserve
> those names.  If it doesn't, and those objects get new system-assigned
> names after the dump-and-reload, then dump restoration can fail when a
> system-assigned name collides with an existing name that is first
> mentioned later in the dump.

Why can't hash partitions be stored in tables the same way as we do TOAST? That should take care of the naming problem.

> If Java has portable hash functions, why can't we?

Java standardizes on a particular unicode encoding (utf-16). Are you suggesting that we do the same? Or is there another solution that I am missing?

Regards,
   Jeff Davis

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