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Add a cardinality function for arrays.

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Unlike our other array functions, this considers the total number of
elements across all dimensions, and returns 0 rather than NULL when the
array has no elements.  But it seems that both of those behaviors are
almost universally disliked, so hopefully that's OK.

Marko Tiikkaja, reviewed by Dean Rasheed and Pavel Stehule
This commit is contained in:
Robert Haas
2014-01-21 12:38:53 -05:00
parent 033b2343fa
commit 01f7808b3e
8 changed files with 93 additions and 1 deletions
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12
src/backend/utils/adt/arrayfuncs.c
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@ -1739,6 +1739,18 @@ array_length(PG_FUNCTION_ARGS)
PG_RETURN_INT32(result);
}
/*
* array_cardinality:
* returns the total number of elements in an array
*/
Datum
array_cardinality(PG_FUNCTION_ARGS)
{
ArrayType *v = PG_GETARG_ARRAYTYPE_P(0);
PG_RETURN_INT32(ArrayGetNItems(ARR_NDIM(v), ARR_DIMS(v)));
}
/*
* array_ref :
* This routine takes an array pointer and a subscript array and returns