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

From Robert Eckhardt
Subject Re: Declarative partitioning - another take
Date
Msg-id CAAtBm9UDmh5=thPgP8mFRK66oAtx5i16jLD7NF29+vnBL2G6mw@mail.gmail.com
Whole thread Raw
In response to Re: Declarative partitioning - another take  (Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>)
List pgsql-hackers
On Tue, Aug 16, 2016 at 2:30 AM, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com> wrote:




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.

In GPDB we have partitioning. It is almost always by date and then often the partitions are for different sizes, i.e. by day for 30 days then by month for 3 years then by year. What we also support, but isn't super performant, is sub-partitioning. 

This is where some on the newer indexing strategies is interesting to me. I see them as synergistic not redundant. 
 

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

pgsql-hackers by date:

Previous
From: Craig Ringer
Date:
Subject: Re: [PATCH] bigint txids vs 'xid' type, new txid_recent(bigint) => xid
Next
From: Stephen Frost
Date:
Subject: Re: patch proposal