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@gmail.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.oliver@gmail.com

--
Angular momentum makes the world go 'round.