Re: New Table Access Methods for Multi and Single Inserts

On Mon, Jan 29, 2024 at 12:57 PM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> On Wed, Jan 17, 2024 at 10:57 PM Bharath Rupireddy
> <bharath.rupireddyforpostgres@gmail.com> wrote:
> >
> > Thank you. I'm attaching v8 patch-set here which includes use of new
> > insert TAMs for COPY FROM. With this, postgres not only will have the
> > new TAM for inserts, but they also can make the following commands
> > faster - CREATE TABLE AS, SELECT INTO, CREATE MATERIALIZED VIEW,
> > REFRESH MATERIALIZED VIEW and COPY FROM. I'll perform some testing in
> > the coming days and post the results here, until then I appreciate any
> > feedback on the patches.
> >
> > I've also added this proposal to CF -
> > https://commitfest.postgresql.org/47/4777/.
>
> Some of the tests related to Incremental Sort added by a recent commit
> 0452b461bc4 in aggregates.sql are failing when the multi inserts
> feature is used for CTAS (like done in 0002 patch). I'm not so sure if
> it's because of the reduction in the CTAS execution times. Execution
> time for table 'btg' created with CREATE TABLE AS added by commit
> 0452b461bc4 with single inserts is 25.3 msec, with multi inserts is
> 17.7 msec. This means that the multi inserts are about 1.43 times or
> 30.04% faster  than the single inserts. Couple of ways to make these
> tests pick Incremental Sort as expected - 1) CLUSTER btg USING abc; or
> 2) increase the number of rows in table btg to 100K from 10K. FWIW, if
> I reduce the number of rows in the table from 10K to 1K, the
> Incremental Sort won't get picked on HEAD with CTAS using single
> inserts. Hence, I chose option (2) to fix the issue.
>
> Please find the attached v9 patch set.
>
> [1]
>  -- Engage incremental sort
>  explain (COSTS OFF) SELECT x,y FROM btg GROUP BY x,y,z,w;
> -                   QUERY PLAN
> --------------------------------------------------
> +          QUERY PLAN
> +------------------------------
>   Group
>     Group Key: x, y, z, w
> -   ->  Incremental Sort
> +   ->  Sort
>           Sort Key: x, y, z, w
> -         Presorted Key: x, y
> -         ->  Index Scan using btg_x_y_idx on btg
> -(6 rows)
> +         ->  Seq Scan on btg
> +(5 rows)

CF bot machine with Windows isn't happy with the compilation [1], so
fixed those warnings and attached v10 patch set.

[1]
[07:35:25.458] [632/2212] Compiling C object
src/backend/postgres_lib.a.p/commands_copyfrom.c.obj
[07:35:25.458] c:\cirrus\src\include\access\tableam.h(1574) : warning
C4715: 'table_multi_insert_slots': not all control paths return a
value
[07:35:25.458] c:\cirrus\src\include\access\tableam.h(1522) : warning
C4715: 'table_insert_begin': not all control paths return a value
[07:35:25.680] c:\cirrus\src\include\access\tableam.h(1561) : warning
C4715: 'table_multi_insert_next_free_slot': not all control paths
return a value
[07:35:25.680] [633/2212] Compiling C object
src/backend/postgres_lib.a.p/commands_createas.c.obj
[07:35:25.680] c:\cirrus\src\include\access\tableam.h(1522) : warning
C4715: 'table_insert_begin': not all control paths return a value
[07:35:26.310] [646/2212] Compiling C object
src/backend/postgres_lib.a.p/commands_matview.c.obj
[07:35:26.310] c:\cirrus\src\include\access\tableam.h(1522) : warning
C4715: 'table_insert_begin': not all control paths return a value

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com