diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2003-04-21 00:22:24 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2003-04-21 00:22:24 +0000 |
| commit | 1dc3a62ec7c9bd3f602689b289a1126fca12fead (patch) | |
| tree | e69ab5da51f8abf37e0db14ea74c045d5cb63fb2 /src/backend/utils/adt/numeric.c | |
| parent | f9ba0a7fe56398e89fe349476d9e437c3197ea28 (diff) | |
| download | postgresql-1dc3a62ec7c9bd3f602689b289a1126fca12fead.tar.gz postgresql-1dc3a62ec7c9bd3f602689b289a1126fca12fead.zip | |
stddev() and variance() should return NULL when there is just one input
value, per recent discussion on pgsql-general.
Diffstat (limited to 'src/backend/utils/adt/numeric.c')
| -rw-r--r-- | src/backend/utils/adt/numeric.c | 36 |
1 files changed, 13 insertions, 23 deletions
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c index e6698fea6c0..c851ae5eb35 100644 --- a/src/backend/utils/adt/numeric.c +++ b/src/backend/utils/adt/numeric.c @@ -14,7 +14,7 @@ * Copyright (c) 1998-2003, PostgreSQL Global Development Group * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v 1.59 2003/03/21 01:58:04 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v 1.60 2003/04/21 00:22:24 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1964,24 +1964,19 @@ numeric_variance(PG_FUNCTION_ARGS) if (NUMERIC_IS_NAN(N) || NUMERIC_IS_NAN(sumX) || NUMERIC_IS_NAN(sumX2)) PG_RETURN_NUMERIC(make_result(&const_nan)); - /* We define VARIANCE of no values to be NULL, of 1 value to be 0 */ - /* N is zero iff no digits (cf. numeric_uminus) */ - if (N->varlen == NUMERIC_HDRSZ) - PG_RETURN_NULL(); - + /* Sample variance is undefined when N is 0 or 1, so return NULL */ init_var(&vN); set_var_from_num(N, &vN); - init_var(&vNminus1); - sub_var(&vN, &const_one, &vNminus1); - - if (cmp_var(&vNminus1, &const_zero) <= 0) + if (cmp_var(&vN, &const_one) <= 0) { free_var(&vN); - free_var(&vNminus1); - PG_RETURN_NUMERIC(make_result(&const_zero)); + PG_RETURN_NULL(); } + init_var(&vNminus1); + sub_var(&vN, &const_one, &vNminus1); + init_var(&vsumX); set_var_from_num(sumX, &vsumX); init_var(&vsumX2); @@ -2045,24 +2040,19 @@ numeric_stddev(PG_FUNCTION_ARGS) if (NUMERIC_IS_NAN(N) || NUMERIC_IS_NAN(sumX) || NUMERIC_IS_NAN(sumX2)) PG_RETURN_NUMERIC(make_result(&const_nan)); - /* We define STDDEV of no values to be NULL, of 1 value to be 0 */ - /* N is zero iff no digits (cf. numeric_uminus) */ - if (N->varlen == NUMERIC_HDRSZ) - PG_RETURN_NULL(); - + /* Sample stddev is undefined when N is 0 or 1, so return NULL */ init_var(&vN); set_var_from_num(N, &vN); - init_var(&vNminus1); - sub_var(&vN, &const_one, &vNminus1); - - if (cmp_var(&vNminus1, &const_zero) <= 0) + if (cmp_var(&vN, &const_one) <= 0) { free_var(&vN); - free_var(&vNminus1); - PG_RETURN_NUMERIC(make_result(&const_zero)); + PG_RETURN_NULL(); } + init_var(&vNminus1); + sub_var(&vN, &const_one, &vNminus1); + init_var(&vsumX); set_var_from_num(sumX, &vsumX); init_var(&vsumX2); |