Re: lock contention on parallel COPY ?

Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>> Tom Lane wrote:
>>> I suppose Andrew didn't yet put in the hack to avoid WAL logging
> 
>> Yes I did. That's what the --truncate-before-load switch does (or should 
>> do).
> 
> Well, it doesn't seem to be having any effect.  Maybe Stefan is testing
> a configuration with xlog archiving enabled?


heh no log archiving - I actually said that I'm now playing with 
--truncate-before-load which seems to cause a noticeable performance (as 
in IO generated) increase but I still see >130000 context switches/s and 
a profile that looks like:


samples  %        symbol name
55526    16.5614  LWLockAcquire
29721     8.8647  DoCopy
26581     7.9281  CopyReadLine
25105     7.4879  LWLockRelease
15743     4.6956  PinBuffer
14725     4.3919  heap_formtuple
9748      2.9075  GetNewObjectId
8059      2.4037  pg_verify_mbstr_len
6825      2.0356  hash_search_with_hash_value
6386      1.9047  s_lock
5645      1.6837  heap_insert
5631      1.6795  PageAddItem
4723      1.4087  pg_atoi


Stefan