Re: [HACKERS] Runtime Partition Pruning

Hi,

The mail was accidently sent before I could complete.

On Tue, Jan 9, 2018 at 2:24 PM, Beena Emerson <memissemerson(at)gmail(dot)com> wrote:
> Hello,
>
> The pruning does not work well with char type:
>
> Case 2: Case with optimizer pruning
> drop table ab_c;
> create table ab_c (a int not null, b int) partition by list(a);
> create table abc_a2 (b int, a int not null) partition by list(b);
> create table abc_a2_b1 partition of abc_a2 for values in (1);
> create table abc_a2_b2 partition of abc_a2 for values in (2);
> create table abc_a2_b3 partition of abc_a2 for values in (3);
> alter table ab_c attach partition abc_a2 for values in (2);
> create table abc_a1 partition of ab_c for values in(1) partition by list (b);
> create table abc_a1_b1 partition of abc_a1 for values in (1);
> create table abc_a1_b2 partition of abc_a1 for values in (2);
> create table abc_a1_b3 partition of abc_a1 for values in (3);
> create table abc_a3 partition of ab_c for values in(3) partition by list (b);
> create table abc_a3_b1 partition of abc_a3 for values in (1);
> create table abc_a3_b2 partition of abc_a3 for values in (2);
> create table abc_a3_b3 partition of abc_a3 for values in (3);
> deallocate abc_q1;

Prepared statement is missing:
prepare abc_q1 (int, int) as select a,b from ab_c where a BETWEEN $1
and $2 AND b IN (3, 2);
>
>
> =# explain (analyze, costs off, summary off, timing off) execute abc_q1 (1, 1);
> QUERY PLAN
> ------------------------------------------------------------------------------
> Append (actual rows=2 loops=1)
> -> Seq Scan on abc_a1_b2 (actual rows=1 loops=1)
> Filter: ((a >= $1) AND (a <= $2) AND (b = ANY ('{3,2}'::integer[])))
> -> Seq Scan on abc_a1_b3 (actual rows=1 loops=1)
> Filter: ((a >= $1) AND (a <= $2) AND (b = ANY ('{3,2}'::integer[])))
> -> Seq Scan on abc_a2_b2 (never executed)
> Filter: ((a >= $1) AND (a <= $2) AND (b = ANY ('{3,2}'::integer[])))
> -> Seq Scan on abc_a2_b3 (never executed)
> Filter: ((a >= $1) AND (a <= $2) AND (b = ANY ('{3,2}'::integer[])))
> -> Seq Scan on abc_a3_b2 (never executed)
> Filter: ((a >= $1) AND (a <= $2) AND (b = ANY ('{3,2}'::integer[])))
> -> Seq Scan on abc_a3_b3 (never executed)
> Filter: ((a >= $1) AND (a <= $2) AND (b = ANY ('{3,2}'::integer[])))
> (13 rows)
>
> postgres=# explain (analyze, costs off, summary off, timing off)
> execute abc_q1 (1, 2);
> ERROR: partition missing from Append subplans

These work fine when the column order of subpartitons are not changed.

Case 3: Optimizer pruning with char types:
Same as case1 with all subpartitions having same col order as parent.

drop table ab_c;
create table ab_c (a int not null, b char) partition by list(a);
create table abc_a2 ( a int not null, b char) partition by list(b);
create table abc_a2_b1 partition of abc_a2 for values in ('1');
create table abc_a2_b2 partition of abc_a2 for values in ('2');
create table abc_a2_b3 partition of abc_a2 for values in ('3');
alter table ab_c attach partition abc_a2 for values in (2);
create table abc_a1 partition of ab_c for values in(1) partition by list (b);
create table abc_a1_b1 partition of abc_a1 for values in ('1');
create table abc_a1_b2 partition of abc_a1 for values in ('2');
create table abc_a1_b3 partition of abc_a1 for values in ('3');
create table abc_a3 partition of ab_c for values in(3) partition by list (b);
create table abc_a3_b1 partition of abc_a3 for values in ('1');
create table abc_a3_b2 partition of abc_a3 for values in ('2');
create table abc_a3_b3 partition of abc_a3 for values in ('3');

deallocate abc_q1;
prepare abc_q1 (int, int) as select a,b from ab_c where a BETWEEN $1
and $2 AND b IN ('3', '2');

-- b4 runtime pruning
=# explain (analyze, costs off, summary off, timing off) execute abc_q1 (1, 8);
QUERY PLAN
---------------------------------------------------------------------------
Append (actual rows=0 loops=1)
-> Seq Scan on abc_a1_b2 (actual rows=0 loops=1)
Filter: ((a >= 1) AND (a <= 8) AND (b = ANY ('{3,2}'::bpchar[])))
-> Seq Scan on abc_a1_b3 (actual rows=0 loops=1)
Filter: ((a >= 1) AND (a <= 8) AND (b = ANY ('{3,2}'::bpchar[])))
-> Seq Scan on abc_a2_b2 (actual rows=0 loops=1)
Filter: ((a >= 1) AND (a <= 8) AND (b = ANY ('{3,2}'::bpchar[])))
-> Seq Scan on abc_a2_b3 (actual rows=0 loops=1)
Filter: ((a >= 1) AND (a <= 8) AND (b = ANY ('{3,2}'::bpchar[])))
-> Seq Scan on abc_a3_b2 (actual rows=0 loops=1)
Filter: ((a >= 1) AND (a <= 8) AND (b = ANY ('{3,2}'::bpchar[])))
-> Seq Scan on abc_a3_b3 (actual rows=0 loops=1)
Filter: ((a >= 1) AND (a <= 8) AND (b = ANY ('{3,2}'::bpchar[])))
(13 rows)

-- after 5 runs

=# explain (analyze, costs off, summary off, timing off) execute abc_q1 (1, 1);
ERROR: operator 1057 is not a member of opfamily 1976

--

Beena Emerson

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