Horton

Re: path toward faster partition pruning

Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>

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From: Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>
To: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Cc: David Rowley <david.rowley@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Beena Emerson <memissemerson@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2017-11-08T06:52:48Z
Lists: pgsql-hackers 
On Mon, Nov 6, 2017 at 3:31 PM, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
wrote:

> Attached updated set of patches, including the fix to make the new pruning
> code handle Boolean partitioning.
>

Hi Amit,

I have tried pruning for different values of constraint exclusion GUC
change, not sure exactly how it should behave, but I can see with the
delete statement pruning is not happening when constraint_exclusion is off,
but select is working as expected. Is this expected behaviour?

create table lp (c1 int, c2 text) partition by list(c1);
create table lp1 partition of lp for values in (1,2);
create table lp2 partition of lp for values in (3,4);
create table lp3 partition of lp for values in (5,6);
insert into lp values (1,'p1'),(2,'p1'),(3,'p2'),(4,'p2'),(5,'p3');

show constraint_exclusion ;
 constraint_exclusion
----------------------
 partition
(1 row)

explain select c1 from lp where c1 >= 1 and c1 < 2;
                        QUERY PLAN
----------------------------------------------------------
 Append  (cost=0.00..29.05 rows=6 width=4)
   ->  Seq Scan on lp1  (cost=0.00..29.05 rows=6 width=4)
         Filter: ((c1 >= 1) AND (c1 < 2))
(3 rows)

explain delete from lp where c1 >= 1 and c1 < 2;
                        QUERY PLAN
----------------------------------------------------------
 Delete on lp  (cost=0.00..29.05 rows=6 width=6)
   Delete on lp1
   ->  Seq Scan on lp1  (cost=0.00..29.05 rows=6 width=6)
         Filter: ((c1 >= 1) AND (c1 < 2))
(4 rows)

set constraint_exclusion = off;

explain select c1 from lp where c1 >= 1 and c1 < 2;
                        QUERY PLAN
----------------------------------------------------------
 Append  (cost=0.00..29.05 rows=6 width=4)
   ->  Seq Scan on lp1  (cost=0.00..29.05 rows=6 width=4)
         Filter: ((c1 >= 1) AND (c1 < 2))
(3 rows)

*explain delete from lp where c1 >= 1 and c1 < 2;*
                        QUERY PLAN
----------------------------------------------------------
 Delete on lp  (cost=0.00..87.15 rows=18 width=6)
   Delete on lp1
   Delete on lp2
   Delete on lp3
   ->  Seq Scan on lp1  (cost=0.00..29.05 rows=6 width=6)
         Filter: ((c1 >= 1) AND (c1 < 2))
   ->  Seq Scan on lp2  (cost=0.00..29.05 rows=6 width=6)
         Filter: ((c1 >= 1) AND (c1 < 2))
   ->  Seq Scan on lp3  (cost=0.00..29.05 rows=6 width=6)
         Filter: ((c1 >= 1) AND (c1 < 2))
(10 rows)

Thanks & Regards,
Rajkumar Raghuwanshi
QMG, EnterpriseDB Corporation

Commits

  1. Fix assorted partition pruning bugs

  2. Make gen_partprune_steps static

  3. Remove useless 'default' clause

  4. Reorganize partitioning code

  5. Use custom hash opclass for hash partition pruning

  6. Blindly attempt to fix sepgsql tests broken due to 9fdb675fc5.

  7. Attempt to fix endianess issues in new hash partition test.

  8. Faster partition pruning

  9. For partitionwise join, match on partcollation, not parttypcoll.

  10. Revise API for partition bound search functions.

  11. Revise API for partition_rbound_cmp/partition_rbound_datum_cmp.

  12. Fix possible crash in partition-wise join.

  13. Refactor code for partition bound searching

  14. New C function: bms_add_range

  15. Add extensive tests for partition pruning.

  16. Add null test to partition constraint for default range partitions.

  17. Remove BufFile's isTemp flag.

  18. Make OWNER TO subcommand mention consistent

  19. Fix index matching for operators with mixed collatable/noncollatable inputs.