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| author | Tom Lane | 2011-05-31 21:53:45 +0000 |
|---|---|---|
| committer | Tom Lane | 2011-05-31 21:53:45 +0000 |
| commit | 6923d699bc3c46ca2c5d8c12fe1c5c39ecfee11d (patch) | |
| tree | 52992a247d48ba2dc48068787d184820d5e61a51 /doc/src/sgml/gist.sgml | |
| parent | ba4cacf0756f71e175d25bac78834715a353e64e (diff) | |
Protect GIST logic that assumes penalty values can't be negative.
Apparently sane-looking penalty code might return small negative values,
for example because of roundoff error. This will confuse places like
gistchoose(). Prevent problems by clamping negative penalty values to
zero. (Just to be really sure, I also made it force NaNs to zero.)
Back-patch to all supported branches.
Alexander Korotkov
Diffstat (limited to 'doc/src/sgml/gist.sgml')
| -rw-r--r-- | doc/src/sgml/gist.sgml | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/doc/src/sgml/gist.sgml b/doc/src/sgml/gist.sgml index f6e31092aa1..78171cfa3fd 100644 --- a/doc/src/sgml/gist.sgml +++ b/doc/src/sgml/gist.sgml @@ -378,6 +378,8 @@ my_decompress(PG_FUNCTION_ARGS) Returns a value indicating the <quote>cost</quote> of inserting the new entry into a particular branch of the tree. Items will be inserted down the path of least <function>penalty</function> in the tree. + Values returned by <function>penalty</function> should be non-negative. + If a negative value is returned, it will be treated as zero. </para> <para> |