Re: jsonb format is pessimal for toast compression
| От | Arthur Silva |
|---|---|
| Тема | Re: jsonb format is pessimal for toast compression |
| Дата | |
| Msg-id | CAO_YK0UzJZw7iksz9n4MyrvpTUyqX5fyH=g1w1v30V50SYVkkg@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: jsonb format is pessimal for toast compression (Josh Berkus <josh@agliodbs.com>) |
| Список | pgsql-hackers |
On Thu, Aug 21, 2014 at 6:20 PM, Josh Berkus <josh@agliodbs.com> wrote:
On 08/20/2014 03:42 PM, Arthur Silva wrote:The same data as upthread.
> What data are you using right now Josh?
Can you test the three patches (9.4 head, 9.4 with Tom's cleanup of
Heikki's patch, and 9.4 with Tom's latest lengths-only) on your workload?
I'm concerned that my workload is unusual and don't want us to make this
decision based entirely on it.
Here's my test results so far with the github archive data.
It's important to keep in mind that the PushEvent event objects that I use in the queries only contains a small number of keys (8 to be precise), so these tests don't really stress the changed code.
Anyway, in this dataset (with the small objects) using the all-lengths patch provide small compression savings but the overhead is minimal.
----------------
Test data: 610MB of Json -- 341969 items
Index size (jsonb_ops): 331MB
Test query 1: SELECT data->'url', data->'actor' FROM t_json WHERE data @> '{"type": "PushEvent"}'
Test query 1 items: 169732
Test query 2: SELECT data FROM t_json WHERE data @> '{"type": "PushEvent"}'
Test query 2 items:
----------------
HEAD (aka, all offsets) EXTENDED
Size: 374MB
Toast Size: 145MB
Test query 1 runtime: 680ms
Test query 2 runtime: 405ms
----------------
HEAD (aka, all offsets) EXTERNAL
Size: 366MB
Toast Size: 333MB
Test query 1 runtime: 505ms
Test query 2 runtime: 350ms
----------------
All Lengths (Tom Lane patch) EXTENDED
Size: 379MB
Toast Size: 108MB
Test query 1 runtime: 720ms
Test query 2 runtime: 420ms
----------------
All Lengths (Tom Lane patch) EXTERNAL
Size: 366MB
Toast Size: 333MB
Test query 1 runtime: 525ms
Test query 2 runtime: 355ms
--
Arthur Silva
Arthur Silva
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