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From: Ron <ronljohnsonjr@gmail.com>
To: pgsql-general@lists.postgresql.org
Subject: Re: When to use PARTITION BY HASH?
Date: Mon, 8 Jun 2020 08:07:04 -0500
Message-ID: <0592c44a-cd2b-da4b-4dea-2017ae41507a@gmail.com> (raw)
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On 6/8/20 3:40 AM, Oleksandr Shulgin wrote:
[snip]
> I've found the original commit adding this feature in version 11: 
> https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=1aba8e651ac3e37e1d2d875842de1e0ed22a6...
> It says:
>
> "Hash partitioning is useful when you want to partition a growing data
> set evenly.  This can be useful to keep table sizes reasonable, which
> makes maintenance operations such as VACUUM faster, or to enable
> partition-wise join."

How does hashed (meaning "randomly?) distribution of records make 
partition-wise joins more efficient?

Or -- since I interpret that as having to do with "locality of data" -- am I 
misunderstanding the meaning of "partition-wise joins"?

-- 
Angular momentum makes the world go 'round.

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