git.postgresql.org Git - postgresql.git/commit

git projects / postgresql.git / commit

summary | shortlog | log | commit | commitdiff | tree
(parent: ee639d2) | patch

Fix performance problem when building a lossy tidbitmap.

Fix performance problem when building a lossy tidbitmap.

As pointed out by Sergey Koposov, repeated invocations of tbm_lossify can
make building a large tidbitmap into an O(N^2) operation. To fix, make
sure we remove more than the minimum amount of information per call, and
add a fallback path to behave sanely if we're unable to fit the bitmap
within the requested amount of memory.

This has been wrong since the tidbitmap code was written, so back-patch
to all supported branches.

RSS Atom