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Ensure that btree sort ordering functions and boolean comparison operators

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give consistent results for all datatypes.  Types float4, float8, and
numeric were broken for NaN values; abstime, timestamp, and interval
were broken for INVALID values; timetz was just plain broken (some
possible pairs of values were neither < nor = nor >).  Also clean up
text, bpchar, varchar, and bit/varbit to eliminate duplicate code and
thereby reduce the probability of similar inconsistencies arising in
the future.
This commit is contained in:
Tom Lane
2001-05-03 19:00:37 +00:00
parent 77fe28f33e
commit 2792374cff
13 changed files with 536 additions and 747 deletions
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138
src/backend/access/nbtree/nbtcompare.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtcompare.c,v 1.41 2001/03/22 03:59:14 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtcompare.c,v 1.42 2001/05/03 19:00:36 tgl Exp $
*
* NOTES
*
@@ -25,7 +25,20 @@
* NOTE: although any negative int32 is acceptable for reporting "<",
* and any positive int32 is acceptable for reporting ">", routines
* that work on 32-bit or wider datatypes can't just return "a - b".
* That could overflow and give the wrong answer.
* That could overflow and give the wrong answer. Also, one should not
* return INT_MIN to report "<", since some callers will negate the result.
*
* NOTE: it is critical that the comparison function impose a total order
* on all non-NULL values of the data type, and that the datatype's
* boolean comparison operators (= < >= etc) yield results consistent
* with the comparison routine. Otherwise bad behavior may ensue.
* (For example, the comparison operators must NOT punt when faced with
* NAN or other funny values; you must devise some collation sequence for
* all such values.) If the datatype is not trivial, this is most
* reliably done by having the boolean operators invoke the same
* three-way comparison code that the btree function does. Therefore,
* this file contains only btree support for "trivial" datatypes ---
* all others are in the /utils/adt/ files that implement their datatypes.
*
* NOTE: these routines must not leak memory, since memory allocated
* during an index access won't be recovered till end of query. This
@@ -33,12 +46,11 @@
* they have to be careful to free any detoasted copy of an input datum.
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "utils/nabstime.h"
#include "utils/builtins.h"
Datum
btboolcmp(PG_FUNCTION_ARGS)
{
@@ -85,34 +97,6 @@ btint8cmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(-1);
}
Datum
btfloat4cmp(PG_FUNCTION_ARGS)
{
float4 a = PG_GETARG_FLOAT4(0);
float4 b = PG_GETARG_FLOAT4(1);
if (a > b)
PG_RETURN_INT32(1);
else if (a == b)
PG_RETURN_INT32(0);
else
PG_RETURN_INT32(-1);
}
Datum
btfloat8cmp(PG_FUNCTION_ARGS)
{
float8 a = PG_GETARG_FLOAT8(0);
float8 b = PG_GETARG_FLOAT8(1);
if (a > b)
PG_RETURN_INT32(1);
else if (a == b)
PG_RETURN_INT32(0);
else
PG_RETURN_INT32(-1);
}
Datum
btoidcmp(PG_FUNCTION_ARGS)
{
@@ -147,20 +131,6 @@ btoidvectorcmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(0);
}
Datum
btabstimecmp(PG_FUNCTION_ARGS)
{
AbsoluteTime a = PG_GETARG_ABSOLUTETIME(0);
AbsoluteTime b = PG_GETARG_ABSOLUTETIME(1);
if (AbsoluteTimeIsBefore(a, b))
PG_RETURN_INT32(-1);
else if (AbsoluteTimeIsBefore(b, a))
PG_RETURN_INT32(1);
else
PG_RETURN_INT32(0);
}
Datum
btcharcmp(PG_FUNCTION_ARGS)
{
@@ -179,79 +149,3 @@ btnamecmp(PG_FUNCTION_ARGS)
PG_RETURN_INT32(strncmp(NameStr(*a), NameStr(*b), NAMEDATALEN));
}
Datum
bttextcmp(PG_FUNCTION_ARGS)
{
text *a = PG_GETARG_TEXT_P(0);
text *b = PG_GETARG_TEXT_P(1);
int res;
unsigned char *ap,
*bp;
#ifdef USE_LOCALE
int la = VARSIZE(a) - VARHDRSZ;
int lb = VARSIZE(b) - VARHDRSZ;
ap = (unsigned char *) palloc(la + 1);
bp = (unsigned char *) palloc(lb + 1);
memcpy(ap, VARDATA(a), la);
*(ap + la) = '\0';
memcpy(bp, VARDATA(b), lb);
*(bp + lb) = '\0';
res = strcoll(ap, bp);
pfree(ap);
pfree(bp);
#else
int len = VARSIZE(a);
/* len is the length of the shorter of the two strings */
if (len > VARSIZE(b))
len = VARSIZE(b);
len -= VARHDRSZ;
ap = (unsigned char *) VARDATA(a);
bp = (unsigned char *) VARDATA(b);
/*
* If the two strings differ in the first len bytes, or if they're the
* same in the first len bytes and they're both len bytes long, we're
* done.
*/
res = 0;
if (len > 0)
{
do
{
res = (int) *ap++ - (int) *bp++;
len--;
} while (res == 0 && len != 0);
}
if (res == 0 && VARSIZE(a) != VARSIZE(b))
{
/*
* The two strings are the same in the first len bytes, and they
* are of different lengths.
*/
if (VARSIZE(a) < VARSIZE(b))
res = -1;
else
res = 1;
}
#endif
/* Avoid leaking memory when handed toasted input. */
PG_FREE_IF_COPY(a, 0);
PG_FREE_IF_COPY(b, 1);
PG_RETURN_INT32(res);
}