pgsql: Fix contrib/seg's GiST picksplit method.

Fix contrib/seg's GiST picksplit method.

This patch replaces Guttman's generalized split method with a simple
sort-by-center-points algorithm. Since the data is only one-dimensional
we don't really need the slow and none-too-stable Guttman method.

This is in part a bug fix, since seg has the same size_alpha versus
size_beta typo that was recently fixed in contrib/cube. It seems
prudent to apply this rather aggressive fix only in HEAD, though.
Back branches will just get the typo fix.

Alexander Korotkov, reviewed by Yeb Havinga

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=2a6ebe70fb2f7ec97a08dc07214fe2ca571d2780

Modified Files
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contrib/seg/seg.c | 194 +++++++++++++++++++++-------------------------------
1 files changed, 78 insertions(+), 116 deletions(-)