RE: speeding up planning with partitions

On Wed, Jan 23, 2019 at 1:35 AM, Amit Langote wrote:
> Rebased due to the heap_open/close() -> table_open/close() change.

Maybe there are not many things I can point out through reviewing the patch, so I ran the performance test against v17 patches instead of reviewing codes.
There are already a lot of tests about partition pruning case and we confirmed performance improves in those cases. In this time, I tested about accessing all partitions case.

I tested with master, master + 0001, master + 0001 + 0002, ..., master + 0001 + 0002 + 0003 + 0004.
I ran pgbench 3 times in each test case and below results are average of those.

[postgresql.conf]
max_parallel_workers = 0
max_parallel_workers_per_gather = 0

[partition table definitions(8192 partitions case)]
create table rt (a int, b int, c int) partition by range (a)
create table rt_1 partition of rt for values from (1) to (2);
...
create table rt_8192 partition of rt for values from (8191) to (8192);

[pgbench commands]
pgbench -n -f update.sql -T 30 postgres

[update.sql(updating partkey case)]
update rt set a = 1;

[update.sql(updating non-partkey case)]
update rt set b = 1;

[results]
updating partkey case:

part-num master 0001 0002 0003 0004
1 8215.34 7924.99 7931.15 8407.40 8475.65
2 7137.49 7026.45 7128.84 7583.08 7593.73
4 5880.54 5896.47 6014.82 6405.33 6398.71
8 4222.96 4446.40 4518.54 4802.43 4785.82
16 2634.91 2891.51 2946.99 3085.81 3087.91
32 935.12 1125.28 1169.17 1199.44 1202.04
64 352.37 405.27 417.09 425.78 424.53
128 236.26 310.01 307.70 315.29 312.81
256 65.36 86.84 87.67 84.39 89.27
512 18.34 24.84 23.55 23.91 23.91
1024 4.83 6.93 6.51 6.45 6.49

updating non-partkey case:

part-num master 0001 0002 0003 0004
1 8862.58 8421.49 8575.35 9843.71 10065.30
2 7715.05 7575.78 7654.28 8800.84 8720.60
4 6249.95 6321.32 6470.26 7278.14 7280.10
8 4514.82 4730.48 4823.37 5382.93 5341.10
16 2815.21 3123.27 3162.51 3422.36 3393.94
32 968.45 1702.47 1722.38 1809.89 1799.88
64 364.17 420.48 432.87 440.20 435.31
128 119.94 148.77 150.47 152.18 143.35
256 45.09 46.35 46.93 48.30 45.85
512 8.74 10.59 10.23 10.27 10.13
1024 2.28 2.60 2.56 2.57 2.51

Looking at the results, if we only apply 0001 or 0001 + 0002 and if number of partition is few like 1 or 2, performance degrades compare to master(A maximum reduction is about 5%, which is 8863->8421).
In all other cases, performance improves compare to master.

--
Yoshikazu Imai