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Commit d663d43

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Fix thinko: have trueTriConsistentFn return GIN_TRUE.
While we're at it, also improve comments in ginlogic.c.
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src/backend/access/gin/ginlogic.c

+21-14
Original file line numberDiff line numberDiff line change
@@ -3,18 +3,25 @@
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* ginlogic.c
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* routines for performing binary- and ternary-logic consistent checks.
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*
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* A GIN operator class provides a consistent function which checks if a
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* tuple matches a qual, when the given set of keys are present in the tuple.
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* The consistent function is passed a TRUE/FALSE argument for every key,
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* indicating if that key is present, and it returns TRUE or FALSE. However,
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* a GIN scan can apply various optimizations, if it can determine that an
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* item matches or doesn't match, even if it doesn't know if some of the keys
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* are present or not. Hence, it's useful to have a ternary-logic consistent
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* function, where each key can be TRUE (present), FALSE (not present),
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* or MAYBE (don't know if present). This file provides such a ternary-logic
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* consistent function, implemented by calling the regular boolean consistent
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* function many times, with all the MAYBE arguments set to all combinations
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* of TRUE and FALSE.
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* A GIN operator class can provide a boolean or ternary consistent
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* function, or both. This file provides both boolean and ternary
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* interfaces to the rest of the GIN code, even if only one of them is
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* implemented by the opclass.
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*
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* Providing a boolean interface when the opclass implements only the
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* ternary function is straightforward - just call the ternary function
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* with the check-array as is, and map the GIN_TRUE, GIN_FALSE, GIN_MAYBE
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* return codes to TRUE, FALSE and TRUE+recheck, respectively. Providing
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* a ternary interface when the opclass only implements a boolean function
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* is implemented by calling the boolean function many times, with all the
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* MAYBE arguments set to all combinations of TRUE and FALSE (up to a
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* certain number of MAYBE arguments).
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*
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* (A boolean function is enough to determine if an item matches, but a
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* GIN scan can apply various optimizations if it can determine that an
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* item matches or doesn't match, even if it doesn't know if some of the
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* keys are present or not. That's what the ternary consistent function
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* is used for.)
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*
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*
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
@@ -43,7 +50,7 @@
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#define MAX_MAYBE_ENTRIES 4
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/*
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* A dummy consistent function for an EVERYTHING key. Just claim it matches.
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* Dummy consistent functions for an EVERYTHING key. Just claim it matches.
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*/
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static bool
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trueConsistentFn(GinScanKey key)
@@ -54,7 +61,7 @@ trueConsistentFn(GinScanKey key)
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static GinLogicValue
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trueTriConsistentFn(GinScanKey key)
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{
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return GIN_MAYBE;
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return GIN_TRUE;
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}
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/*

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