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Commit659f681

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Change array comparison rules to consider dimensionality information,
not only the array contents, before claiming two arrays are equal.Per recent discussion.
1 parentdaea4d8 commit659f681

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2 files changed

+47
-10
lines changed

2 files changed

+47
-10
lines changed

‎doc/src/sgml/func.sgml

Lines changed: 14 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.294 2005/11/1901:50:08 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.295 2005/11/1919:44:54 tgl Exp $
33
PostgreSQL documentation
44
-->
55

@@ -7403,6 +7403,19 @@ SELECT NULLIF(value, '(none)') ...
74037403
</tgroup>
74047404
</table>
74057405

7406+
<para>
7407+
Array comparisons compare the array contents element-by-element,
7408+
using the default btree comparison function for the element data type.
7409+
In multidimensional arrays the elements are visited in row-major order
7410+
(last subscript varies most rapidly).
7411+
If the contents of two arrays are equal but the dimensionality is
7412+
different, the first difference in the dimensionality information
7413+
determines the sort order. (This is a change from versions of
7414+
<productname>PostgreSQL</> prior to 8.2: older versions would claim
7415+
that two arrays with the same contents were equal, even if the
7416+
number of dimensions or subscript ranges were different.)
7417+
</para>
7418+
74067419
<para>
74077420
See <xref linkend="arrays"> for more details about array operator
74087421
behavior.

‎src/backend/utils/adt/arrayfuncs.c

Lines changed: 33 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.124 2005/11/17 22:14:52 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.125 2005/11/19 19:44:55 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -2965,10 +2965,9 @@ array_eq(PG_FUNCTION_ARGS)
29652965
intndims2=ARR_NDIM(array2);
29662966
int*dims1=ARR_DIMS(array1);
29672967
int*dims2=ARR_DIMS(array2);
2968-
intnitems1=ArrayGetNItems(ndims1,dims1);
2969-
intnitems2=ArrayGetNItems(ndims2,dims2);
29702968
Oidelement_type=ARR_ELEMTYPE(array1);
29712969
boolresult= true;
2970+
intnitems;
29722971
TypeCacheEntry*typentry;
29732972
inttyplen;
29742973
booltypbyval;
@@ -2986,8 +2985,9 @@ array_eq(PG_FUNCTION_ARGS)
29862985
(errcode(ERRCODE_DATATYPE_MISMATCH),
29872986
errmsg("cannot compare arrays of different element types")));
29882987

2989-
/* fast path if the arrays do not have the same number of elements */
2990-
if (nitems1!=nitems2)
2988+
/* fast path if the arrays do not have the same dimensionality */
2989+
if (ndims1!=ndims2||
2990+
memcmp(dims1,dims2,2*ndims1*sizeof(int))!=0)
29912991
result= false;
29922992
else
29932993
{
@@ -3021,13 +3021,14 @@ array_eq(PG_FUNCTION_ARGS)
30213021
NULL,NULL);
30223022

30233023
/* Loop over source data */
3024+
nitems=ArrayGetNItems(ndims1,dims1);
30243025
ptr1=ARR_DATA_PTR(array1);
30253026
ptr2=ARR_DATA_PTR(array2);
30263027
bitmap1=ARR_NULLBITMAP(array1);
30273028
bitmap2=ARR_NULLBITMAP(array2);
30283029
bitmask=1;/* use same bitmask for both arrays */
30293030

3030-
for (i=0;i<nitems1;i++)
3031+
for (i=0;i<nitems;i++)
30313032
{
30323033
Datumelt1;
30333034
Datumelt2;
@@ -3221,13 +3222,13 @@ array_cmp(FunctionCallInfo fcinfo)
32213222
NULL,NULL);
32223223

32233224
/* Loop over source data */
3225+
min_nitems=Min(nitems1,nitems2);
32243226
ptr1=ARR_DATA_PTR(array1);
32253227
ptr2=ARR_DATA_PTR(array2);
32263228
bitmap1=ARR_NULLBITMAP(array1);
32273229
bitmap2=ARR_NULLBITMAP(array2);
32283230
bitmask=1;/* use same bitmask for both arrays */
32293231

3230-
min_nitems=Min(nitems1,nitems2);
32313232
for (i=0;i<min_nitems;i++)
32323233
{
32333234
Datumelt1;
@@ -3317,8 +3318,31 @@ array_cmp(FunctionCallInfo fcinfo)
33173318
}
33183319
}
33193320

3320-
if ((result==0)&& (nitems1!=nitems2))
3321-
result= (nitems1<nitems2) ?-1 :1;
3321+
/*
3322+
* If arrays contain same data (up to end of shorter one), apply additional
3323+
* rules to sort by dimensionality. The relative significance of the
3324+
* different bits of information is historical; mainly we just care that
3325+
* we don't say "equal" for arrays of different dimensionality.
3326+
*/
3327+
if (result==0)
3328+
{
3329+
if (nitems1!=nitems2)
3330+
result= (nitems1<nitems2) ?-1 :1;
3331+
elseif (ndims1!=ndims2)
3332+
result= (ndims1<ndims2) ?-1 :1;
3333+
else
3334+
{
3335+
/* this relies on LB array immediately following DIMS array */
3336+
for (i=0;i<ndims1*2;i++)
3337+
{
3338+
if (dims1[i]!=dims2[i])
3339+
{
3340+
result= (dims1[i]<dims2[i]) ?-1 :1;
3341+
break;
3342+
}
3343+
}
3344+
}
3345+
}
33223346

33233347
/* Avoid leaking memory when handed toasted input. */
33243348
PG_FREE_IF_COPY(array1,0);

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