Re: zheap: a new storage format for PostgreSQL

> On Thu, Mar 1, 2018 at 7:39 PM Amit Kapila <amit.kapila16@gmail.com> wrote:

I did some testing for performance of COPY command for zheap against heap, here are my results,
Machine : cthulhu, (is a 8 node numa machine with 500GB of RAM)
server non default settings: shared buffers 32GB, max_wal_size = 20GB, min_wal_size = 15GB

Test tables and data:
----------------------------
I have used pgbench_accounts table of pgbench tool as data source with 3 different scale factors 100, 1000, 2000. Both heap and zheap table is lookalike of pgbench_accounts

CREATE TABLE pgbench_zheap (LIKE pgbench_accounts) WITH (storage_engine='zheap');
CREATE TABLE pgbench_heap (LIKE pgbench_accounts) WITH (storage_engine='heap');

Test Commands:
Command to generate datafile: COPY pgbench_accounts TO '/mnt/data-mag/mithun.cy/zheapperfbin/bin/pgbench.data';

Command to load from datafile:
COPY pgbench_heap FROM '/mnt/data-mag/mithun.cy/zheapperfbin/bin/pgbench.data'; -- heap table
COPY pgbench_zheap FROM '/mnt/data-mag/mithun.cy/zheapperfbin/bin/pgbench.data'; -- zheap table

Results
======

Scale factor : 100
------------------------
zheap table size : 1028 MB
heap table size: 1281 MB
-- table size reduction: 19% size reduction.
zheap wal size: 1007 MB
heap wal size: 1024 MB
-- wal size difference: 1.6% size reduction.
zheap COPY  execution time: 24869.451 ms
heap COPY  execution time: 25858.773 ms
-- % of improvement -- 3.8% reduction in execution time for zheap

Scale factor : 1000
-------------------------
zheap table size : 10 GB
heap table size: 13 GB
-- table size reduction: 23% size reduction.
zheap wal size: 10071 MB
heap wal size: 10243 MB
-- wal size difference: 1.67% size reduction.
zheap COPY  execution time: 270790.235 ms
heap COPY  execution time:  280325.632 ms
-- % of improvement -- 3.4% reduction in execution time for zheap

Scale factor : 2000
-------------------------
zheap table size : 20GB
heap table size: 25GB
-- table size reduction: 20% size reduction.
zheap wal size: 20142 MB
heap wal size: 20499 MB
-- wal size difference: 1.7% size reduction.
zheap COPY  execution time: 523702.904 ms
heap COPY  execution time: 537537.720 ms
-- % of improvement -- 2.5 % reduction in execution time for zheap

COPY command seems to have improved very slightly with zheap in both with size of wal and execution time. I also did some tests with insert statement where I could see some regression in zheap when compared to heap with respect to execution time. With further more investigation I will reply here.

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Thanks and Regards
Mithun Chicklore Yogendra
EnterpriseDB: http://www.enterprisedb.com