Re: lock contention on parallel COPY ?

On Fri, 2008-09-26 at 14:00 -0400, Tom Lane wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
> > Stefan Kaltenbrunner <stefan@kaltenbrunner.cc> writes:
> >> 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
> 
> > Probably loading a table with a generated PK or loading data in
> > ascending sequence, so its contending heavily for the rightmost edge of
> > the index.
> 
> No, given that DoCopy and CopyReadLine are right up there, I think we're
> still looking at the COPY phase, not index building.
> 
> The profile will probably change completely once index building
> starts...

Sorry, was assuming we were loading with indexes on, which is wrong.

Agree the profile looks odd.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support