Matthew wrote:
On Tue, 5 Feb 2008, Richard Huxton wrote:
Why would you need to lock the table?
Because you're not really writing the WAL, which means you can't let
anyone else get their data into any of the blocks you are writing
into. You'd basically want to write the disk blocks then "attach" them
in some way.
So what's wrong with "reserving" the space using the WAL, then everyone
else will know. After all, when you write the data to the WAL, you must
have an idea of where it is meant to end up. My suggestion is that you
go through all the motions of writing the data to the WAL, just without
the data bit.
Well, now you're looking at page-level locking for the data blocks, or
at least something very similar. Not sure what you'd do with indexes
though - don't see a simple way of avoiding a large lock on a btree index.
If you reserved the space in advance that could work. But you don't know
how much to reserve until you've copied it in.
You could of course have a set of co-operating processes all
bulk-loading while maintaining a table-lock outside of the those. It
feels like things are getting complicated then though.
--
Richard Huxton
Archonet Ltd
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