Re: Declarative partitioning - another take - Mailing list pgsql-hackers

From Ashutosh Bapat
Subject Re: Declarative partitioning - another take
Date
Msg-id CAFjFpRd=WjuS_K_YhDta0PtTYLijDyZ_NRQRV+N50DDNDgDP3Q@mail.gmail.com
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In response to Re: Declarative partitioning - another take  (Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>)
Responses Re: Declarative partitioning - another take  (Robert Eckhardt <reckhardt@pivotal.io>)
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I think it makes sense to keep calling it a table because it has all the
logical properties of a table even though it will differ from a regular
table on the basis of physical implementation details such as that it does
not own physical storage.  Am I missing something?

>
> +      <entry><structfield>partexprs</structfield></entry>
>
> There's a certain symmetry between this and what we do for indexes,
> but I'm wondering whether there's a use case for partitioning a table
> by an expression rather than a column value.  I suppose if you've
> already done the work, there's no harm in supporting it.

Yeah, it's not a whole lot of code to manage expressions alongside simple
column references.

Users who would like to partition their tables by "age" will partition those by the month or year extracted out of a date column e.g. order_date. They will find it convenient to use an expression (extract(month from date)) as a partition key, instead of storing month or year as a separate column.

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

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