Hi hackers! I was reviewing Paul Ramsey's TOAST patch[0] and noticed that there is a big room for improvement in performance of pglz compression and decompression.
With Vladimir we started to investigate ways to boost byte copying and eventually created test suit[1] to investigate performance of compression and decompression. This is and extension with single function test_pglz() which performs tests for different: 1. Data payloads 2. Compression implementations 3. Decompression implementations Currently we test mostly decompression improvements against two WALs and one data file taken from pgbench-generated database. Any suggestion on more relevant data payloads are very welcome. My laptop tests show that our decompression implementation [2] can be from 15% to 50% faster. Also I've noted that compression is extremely slow, ~30 times slower than decompression. I believe we can do something about it. We focus only on boosting existing codec without any considerations of other compression algorithms. Any comments are much appreciated. Most important questions are: 1. What are relevant data sets? 2. What are relevant CPUs? I have only XEON-based servers and few laptops\desktops with intel CPUs 3. If compression is 30 times slower, should we better focus on compression instead of decompression? Best regards, Andrey Borodin. [0] https://www.postgresql.org/message-id/flat/CANP8%2BjKcGj-JYzEawS%2BCUZnfeGKq4T5LswcswMP4GUHeZEP1ag%40mail.gmail.com [1] https://github.com/x4m/test_pglz [2] https://www.postgresql.org/message-id/C2D8E5D5-3E83-469B-8751-1C7877C2A5F2%40yandex-team.ru
