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authorTom Lane2011-05-31 21:54:01 +0000
committerTom Lane2011-05-31 21:54:01 +0000
commit8057b7554bde98d887f02f5c0c7aeca01c8b52c9 (patch)
tree17181ab434a846067ecca843e33cdf23374cea14
parent0699d053ba8eede356e59e6e220716891cbee7fe (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
-rw-r--r--doc/src/sgml/gist.sgml2
-rw-r--r--src/backend/access/gist/gistutil.c14
2 files changed, 13 insertions, 3 deletions
diff --git a/doc/src/sgml/gist.sgml b/doc/src/sgml/gist.sgml
index eddaaad5dfa..fd5800f336c 100644
--- a/doc/src/sgml/gist.sgml
+++ b/doc/src/sgml/gist.sgml
@@ -374,6 +374,8 @@ 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>
diff --git a/src/backend/access/gist/gistutil.c b/src/backend/access/gist/gistutil.c
index a2e8fe0cfb9..2e70b5e5c7d 100644
--- a/src/backend/access/gist/gistutil.c
+++ b/src/backend/access/gist/gistutil.c
@@ -13,6 +13,8 @@
*/
#include "postgres.h"
+#include <math.h>
+
#include "access/gist_private.h"
#include "access/reloptions.h"
#include "storage/freespace.h"
@@ -532,16 +534,22 @@ gistpenalty(GISTSTATE *giststate, int attno,
{
float penalty = 0.0;
- if (giststate->penaltyFn[attno].fn_strict == FALSE || (isNullOrig == FALSE && isNullAdd == FALSE))
+ if (giststate->penaltyFn[attno].fn_strict == FALSE ||
+ (isNullOrig == FALSE && isNullAdd == FALSE))
+ {
FunctionCall3(&giststate->penaltyFn[attno],
PointerGetDatum(orig),
PointerGetDatum(add),
PointerGetDatum(&penalty));
+ /* disallow negative or NaN penalty */
+ if (isnan(penalty) || penalty < 0.0)
+ penalty = 0.0;
+ }
else if (isNullOrig && isNullAdd)
penalty = 0.0;
else
- penalty = 1e10; /* try to prevent to mix null and non-null
- * value */
+ penalty = 1e10; /* try to prevent mixing null and non-null
+ * values */
return penalty;
}