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author | Tom Lane <tgl@sss.pgh.pa.us> | 2006-03-21 19:49:19 +0000 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2006-03-21 19:49:19 +0000 |
commit | a155814e373fde80e7fae7d240bd100370c3b2b3 (patch) | |
tree | 50e8c7ec3ad5364f1ef118f8d8b72abc37e54e64 /contrib/intarray/_int_gist.c | |
parent | 85fa81f65bb2394b455036bb658403577f85e766 (diff) | |
download | postgresql-a155814e373fde80e7fae7d240bd100370c3b2b3.tar.gz postgresql-a155814e373fde80e7fae7d240bd100370c3b2b3.zip |
Improve performance of our private version of qsort. Per recent testing,
the logic it contained to switch to insertion sort for near-sorted input was
in fact a big loss, because it could fairly easily be fooled into applying
insertion sort to large subfiles that weren't all that well ordered. Remove
that, and instead add a simple check for already-perfectly-sorted input, as
per suggestion from Dann Corbit. This adds at worst O(N*lgN) overhead, and
usually far less, while sometimes allowing a subfile sort to finish in O(N)
time. Preliminary testing says this is an improvement over the basic
Bentley & McIlroy code for many nonrandom inputs, and it costs almost
nothing when the input is random.
Diffstat (limited to 'contrib/intarray/_int_gist.c')
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