Re: Partitioning on the date part of a timestamp & PK issues

Use RANGE partitioning. https://www.postgresql.org/docs/12/ddl-partitioning.html

CREATE TABLE t (
    guid uuid not null,
    seq smallint not null,
    tid smallint not null,
    ts timestamp without time zone not null,
    x real,
    y real,
    z real,
    primary key (guid, tid, seq, ts)
)   partition by range (ts);

CREATE TABLE t_y2021m07 PARTITION OF measurement
    FOR VALUES FROM ('2021-07-01') TO ('2021-08-01');

CREATE TABLE measurement_y2021m08 PARTITION OF measurement
    FOR VALUES FROM ('2021-08-01') TO ('2021-09-01');

On 7/15/21 5:09 PM, Wells Oliver wrote:
> Correct me if I'm wrong, but wouldn't partitioning by just the ts column
> create a ton of partitions per the granular nature of timestamps? Or do I
> wildly misunderstand this? Another Very Large Table we have partitioned by
> a date field cleanly creates monthly partitions.
>
> On Thu, Jul 15, 2021 at 3:06 PM Ron <ronljohnsonjr(at)gmail(dot)com
> <mailto:ronljohnsonjr(at)gmail(dot)com>> wrote:
>
> On 7/15/21 3:10 PM, Wells Oliver wrote:
> > I have a table like so:
> >
> > CREATE TABLE t (
> >     guid uuid not null,
> >     seq smallint not null,
> >     tid smallint not null,
> >     ts timestamp without time zone not null,
> >     x real,
> >     y real,
> >     z real,
> >     primary key (guid, tid, seq)
> > ) partition by range (extract(date from ts));
> >
> > Which results in the error:
> >
> > ERROR:  unsupported PRIMARY KEY constraint with partition key definition
> > DETAIL:  PRIMARY KEY constraints cannot be used when partition keys
> > include expressions.
> >
> > Is there a suitable way to get around this? I can make an additional
> date
> > col in the table to use for the partition range, but given the
> amount of
> > data we will have, I am trying to be cognizant of storage concerns.
> >
> > The PK is the PK, so I'm not sure what options I have there.
>
> Why do you feel the need to "extract(date from ts)" instead of just
> partitioning by "ts"?
>
> --
> Angular momentum makes the world go 'round.
>
>
>
>
> --
> Wells Oliver
> wells(dot)oliver(at)gmail(dot)com <mailto:wellsoliver(at)gmail(dot)com>

--
Angular momentum makes the world go 'round.