Gavin Sherry wrote:
On Tue, Feb 26, 2008 at 02:43:51PM +0000, Simon Riggs wrote:
Following patch implements a simple mechanism to keep a buffer pinned
while we are bulk loading.
CK Tan and I worked on something similar but the problem we discovered
was self locking. Consider a primary key: we insert a tuple into a
buffer and do not release the exclusive lock. The btree code fetches the
buffer and tries to share lock it, but we've already exclusive locked
it. Oops. The performance improvement, though, makes it worth seeing if
there is a solution.
That's not a problem if you only keep the buffer pinned, not locked. In
my experience, pinning is the more expensive part, with the lookup into
the buffer lookup table. Locking isn't free either, of course, but just
avoiding the pin+unpin would help a lot.
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