Simon Riggs wrote:
> On Tue, 2008-02-05 at 14:43 +0000, Richard Huxton wrote:
>> Simon Riggs wrote:
>>> On Tue, 2008-02-05 at 15:06 +0100, Dimitri Fontaine wrote:
>>>> Le lundi 04 février 2008, Jignesh K. Shah a écrit :
>>>>> Multiple table loads ( 1 per table) spawned via script is bit better
>>>>> but hits wal problems.
>>>> pgloader will too hit the WAL problem, but it still may have its benefits, or
>>>> at least we will soon (you can already if you take it from CVS) be able to
>>>> measure if the parallel loading at the client side is a good idea perf. wise.
>>> Should be able to reduce lock contention, but not overall WAL volume.
>> In the case of a bulk upload to an empty table (or partition?) could you
>> not optimise the WAL away? That is, shouldn't the WAL basically be a
>> simple transformation of the on-disk blocks? You'd have to explicitly
>> sync the file(s) for the table/indexes of course, and you'd need some
>> work-around for WAL shipping, but it might be worth it for you chaps
>> with large imports.
>
> Only by locking the table, which serializes access, which then slows you
> down or at least restricts other options. Plus if you use pg_loader then
> you'll find only the first few rows optimized and all the rest not.
Hmm - the table-locking requirement is true enough, but why would
pg_loader cause problems after the first few rows?
--
Richard Huxton
Archonet Ltd