#include <limits.h>
#include <math.h>
+#include "access/hash.h"
#include "catalog/pg_type.h"
#include "libpq/pqformat.h"
#include "utils/array.h"
return result;
}
+Datum
+hash_numeric(PG_FUNCTION_ARGS)
+{
+ Numeric key = PG_GETARG_NUMERIC(0);
+ Datum digit_hash;
+ Datum result;
+ int weight;
+ int start_offset;
+ int end_offset;
+ int i;
+ int hash_len;
+
+ /* If it's NaN, don't try to hash the rest of the fields */
+ if (NUMERIC_IS_NAN(key))
+ PG_RETURN_UINT32(0);
+
+ weight = key->n_weight;
+ start_offset = 0;
+ end_offset = 0;
+
+ /*
+ * Omit any leading or trailing zeros from the input to the
+ * hash. The numeric implementation *should* guarantee that
+ * leading and trailing zeros are suppressed, but we're
+ * paranoid. Note that we measure the starting and ending offsets
+ * in units of NumericDigits, not bytes.
+ */
+ for (i = 0; i < NUMERIC_NDIGITS(key); i++)
+ {
+ if (NUMERIC_DIGITS(key)[i] != (NumericDigit) 0)
+ break;
+
+ start_offset++;
+ /*
+ * The weight is effectively the # of digits before the
+ * decimal point, so decrement it for each leading zero we
+ * skip.
+ */
+ weight--;
+ }
+
+ /*
+ * If there are no non-zero digits, then the value of the number
+ * is zero, regardless of any other fields.
+ */
+ if (NUMERIC_NDIGITS(key) == start_offset)
+ PG_RETURN_UINT32(-1);
+
+ for (i = NUMERIC_NDIGITS(key) - 1; i >= 0; i--)
+ {
+ if (NUMERIC_DIGITS(key)[i] != (NumericDigit) 0)
+ break;
+
+ end_offset++;
+ }
+
+ /* If we get here, there should be at least one non-zero digit */
+ Assert(start_offset + end_offset < NUMERIC_NDIGITS(key));
+
+ /*
+ * Note that we don't hash on the Numeric's scale, since two
+ * numerics can compare equal but have different scales. We also
+ * don't hash on the sign, although we could: since a sign
+ * difference implies inequality, this shouldn't affect correctness.
+ */
+ hash_len = NUMERIC_NDIGITS(key) - start_offset - end_offset;
+ digit_hash = hash_any((unsigned char *) (NUMERIC_DIGITS(key) + start_offset),
+ hash_len * sizeof(NumericDigit));
+
+ /* Mix in the weight, via XOR */
+ result = digit_hash ^ weight;
+
+ PG_RETURN_DATUM(result);
+}
+
/* ----------------------------------------------------------------------
*
/* NUMERIC type - OID's 1700-1799 */
DATA(insert OID = 1751 ( "-" PGNSP PGUID l f f 0 1700 1700 0 0 numeric_uminus - - ));
-DATA(insert OID = 1752 ( "=" PGNSP PGUID b t f 1700 1700 16 1752 1753 numeric_eq eqsel eqjoinsel ));
+DATA(insert OID = 1752 ( "=" PGNSP PGUID b t t 1700 1700 16 1752 1753 numeric_eq eqsel eqjoinsel ));
DATA(insert OID = 1753 ( "<>" PGNSP PGUID b f f 1700 1700 16 1753 1752 numeric_ne neqsel neqjoinsel ));
DATA(insert OID = 1754 ( "<" PGNSP PGUID b f f 1700 1700 16 1756 1757 numeric_lt scalarltsel scalarltjoinsel ));
DATA(insert OID = 1755 ( "<=" PGNSP PGUID b f f 1700 1700 16 1757 1756 numeric_le scalarltsel scalarltjoinsel ));
projects / users / simon / postgres.git / commitdiff