Commit 327b2576 authored by Tom Lane's avatar Tom Lane

Improve comment.

parent 4448917d
...@@ -394,10 +394,11 @@ static TypeInfo TypeInfo_varbit = {true, leftmostvalue_varbit, bitcmp}; ...@@ -394,10 +394,11 @@ static TypeInfo TypeInfo_varbit = {true, leftmostvalue_varbit, bitcmp};
GIN_SUPPORT(varbit) GIN_SUPPORT(varbit)
/* /*
* Numeric type hasn't applicable left-most value, so NULL * Numeric type hasn't a real left-most value, so we use PointerGetDatum(NULL)
* is used for that. NULL will never be an argument for a C-level * (*not* a SQL NULL) to represent that. We can get away with that because
* numeric function except gin_numeric_cmp and it will not be stored * the value returned by our leftmostvalue function will never be stored in
* somewhere and it could not be returned in any user SQL query. * the index nor passed to anything except our compare and prefix-comparison
* functions. The same trick could be used for other pass-by-reference types.
*/ */
#define NUMERIC_IS_LEFTMOST(x) ((x) == NULL) #define NUMERIC_IS_LEFTMOST(x) ((x) == NULL)
......
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