29.01.2016 20:43, Thom Brown:
On 29 January 2016 at 16:50, Anastasia Lubennikova
<a.lubennik...@postgrespro.ru> wrote:
29.01.2016 19:01, Thom Brown:
On 29 January 2016 at 15:47, Aleksander Alekseev
<a.aleks...@postgrespro.ru> wrote:
I tested this patch on x64 and ARM servers for a few hours today. The
only problem I could find is that INSERT works considerably slower after
applying a patch. Beside that everything looks fine - no crashes, tests
pass, memory doesn't seem to leak, etc.
Thank you for testing. I rechecked that, and insertions are really very very
very slow. It seems like a bug.
Okay, now for some badness. I've restored a database containing 2
tables, one 318MB, another 24kB. The 318MB table contains 5 million
rows with a sequential id column. I get a problem if I try to delete
many rows from it:
# delete from contacts where id % 3 != 0 ;
WARNING: out of shared memory
WARNING: out of shared memory
WARNING: out of shared memory
I didn't manage to reproduce this. Thom, could you describe exact steps
to reproduce this issue please?
Sure, I used my pg_rep_test tool to create a primary (pg_rep_test
-r0), which creates an instance with a custom config, which is as
follows:
shared_buffers = 8MB
max_connections = 7
wal_level = 'hot_standby'
cluster_name = 'primary'
max_wal_senders = 3
wal_keep_segments = 6
Then create a pgbench data set (I didn't originally use pgbench, but
you can get the same results with it):
createdb -p 5530 pgbench
pgbench -p 5530 -i -s 100 pgbench
And delete some stuff:
thom@swift:~/Development/test$ psql -p 5530 pgbench
Timing is on.
psql (9.6devel)
Type "help" for help.
➤ psql://thom@[local]:5530/pgbench
# DELETE FROM pgbench_accounts WHERE aid % 3 != 0;
WARNING: out of shared memory
WARNING: out of shared memory
WARNING: out of shared memory
WARNING: out of shared memory
WARNING: out of shared memory
WARNING: out of shared memory
WARNING: out of shared memory
...
WARNING: out of shared memory
WARNING: out of shared memory
DELETE 6666667
Time: 22218.804 ms
There were 358 lines of that warning message. I don't get these
messages without the patch.
Thom
Thank you for this report.
I tried to reproduce it, but I couldn't. Debug will be much easier now.
I hope I'll fix these issueswithin the next few days.
BTW, I found a dummy mistake, the previous patch contains some unrelated
changes. I fixed it in the new version (attached).
Thanks. Well I've tested this latest patch, and the warnings are no
longer generated. However, the index sizes show that the patch
doesn't seem to be doing its job, so I'm wondering if you removed too
much from it.
Huh, this patch seems to be enchanted) It works fine for me. Did you
perform "make distclean"?
Anyway, I'll send a new version soon.
I just write here to say that I do not disappear and I do remember about
the issue.
I even almost fixed the insert speed problem. But I'm very very busy
this week.
I'll send an updated patch next week as soon as possible.
Thank you for attention to this work.
--
Anastasia Lubennikova
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company
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