Allow zero-dimensional (ie, empty) arrays in contrib/ltree operations.

The main motivation for changing this is bug #4921, in which it's pointed out
that it's no longer safe to apply ltree operations to the result of
ARRAY(SELECT ...) if the sub-select might return no rows.  Before 8.3,
the ARRAY() construct would return NULL, which might or might not be helpful
but at least it wouldn't result in an error.  Now it returns an empty array
which results in a failure for no good reason, since the ltree operations
are all perfectly capable of dealing with zero-element arrays.

As far as I can find, these ltree functions are the only places where zero
array dimensionality is rejected unnecessarily.

Back-patch to 8.3 to prevent behavioral regression of queries that worked
in older releases.

diff --git a/contrib/ltree/_ltree_gist.c b/contrib/ltree/_ltree_gist.c
index 34ec2552ca4b90367b9462d310a621cca2d4db5b..3a0e7769fffd060726a424eed15c0486b21407fd 100644 (file)
--- a/contrib/ltree/_ltree_gist.c
+++ b/contrib/ltree/_ltree_gist.c
@@ -84,7 +84,7 @@ _ltree_compress(PG_FUNCTION_ARGS)
                int                     num = ArrayGetNItems(ARR_NDIM(val), ARR_DIMS(val));
                ltree      *item = (ltree *) ARR_DATA_PTR(val);
 
-               if (ARR_NDIM(val) != 1)
+               if (ARR_NDIM(val) > 1)
                        ereport(ERROR,
                                        (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                                         errmsg("array must be one-dimensional")));
@@ -530,7 +530,7 @@ _arrq_cons(ltree_gist * key, ArrayType *_query)
        lquery     *query = (lquery *) ARR_DATA_PTR(_query);
        int                     num = ArrayGetNItems(ARR_NDIM(_query), ARR_DIMS(_query));
 
-       if (ARR_NDIM(_query) != 1)
+       if (ARR_NDIM(_query) > 1)
                ereport(ERROR,
                                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                                 errmsg("array must be one-dimensional")));

diff --git a/contrib/ltree/_ltree_op.c b/contrib/ltree/_ltree_op.c
index f93d2bb8889574dc54efec1cdb2eee8cf5418a1c..de5cb90a51e9ba266ce242aa844e8e04f4d5b997 100644 (file)
--- a/contrib/ltree/_ltree_op.c
+++ b/contrib/ltree/_ltree_op.c
@@ -43,7 +43,7 @@ array_iterator(ArrayType *la, PGCALL2 callback, void *param, ltree ** found)
        int                     num = ArrayGetNItems(ARR_NDIM(la), ARR_DIMS(la));
        ltree      *item = (ltree *) ARR_DATA_PTR(la);
 
-       if (ARR_NDIM(la) != 1)
+       if (ARR_NDIM(la) > 1)
                ereport(ERROR,
                                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                                 errmsg("array must be one-dimensional")));
@@ -143,7 +143,7 @@ _lt_q_regex(PG_FUNCTION_ARGS)
        bool            res = false;
        int                     num = ArrayGetNItems(ARR_NDIM(_query), ARR_DIMS(_query));
 
-       if (ARR_NDIM(_query) != 1)
+       if (ARR_NDIM(_query) > 1)
                ereport(ERROR,
                                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                                 errmsg("array must be one-dimensional")));
@@ -301,7 +301,7 @@ _lca(PG_FUNCTION_ARGS)
        ltree     **a,
                           *res;
 
-       if (ARR_NDIM(la) != 1)
+       if (ARR_NDIM(la) > 1)
                ereport(ERROR,
                                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                                 errmsg("array must be one-dimensional")));

diff --git a/contrib/ltree/lquery_op.c b/contrib/ltree/lquery_op.c
index 8522c5e0538a0404842f8cd9c15e6057c6ce4c09..c0f4309b78b5fdc45597dea3a2d00688742d92af 100644 (file)
--- a/contrib/ltree/lquery_op.c
+++ b/contrib/ltree/lquery_op.c
@@ -1,7 +1,7 @@
 /*
  * op function for ltree and lquery
  * Teodor Sigaev <teodor@stack.net>
- * $PostgreSQL: pgsql/contrib/ltree/lquery_op.c,v 1.11 2006/10/04 00:29:45 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/ltree/lquery_op.c,v 1.11.4.1 2010/02/24 18:02:36 tgl Exp $
  */
 
 #include "ltree.h"
@@ -325,7 +325,7 @@ lt_q_regex(PG_FUNCTION_ARGS)
        bool            res = false;
        int                     num = ArrayGetNItems(ARR_NDIM(_query), ARR_DIMS(_query));
 
-       if (ARR_NDIM(_query) != 1)
+       if (ARR_NDIM(_query) > 1)
                ereport(ERROR,
                                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                                 errmsg("array must be one-dimensional")));

diff --git a/contrib/ltree/ltree_gist.c b/contrib/ltree/ltree_gist.c
index dea0b9c3863ab35de53ad519d0f31f7554b1a5de..921643d21290b02176e194c64d0e0808c1e52b75 100644 (file)
--- a/contrib/ltree/ltree_gist.c
+++ b/contrib/ltree/ltree_gist.c
@@ -1,7 +1,7 @@
 /*
  * GiST support for ltree
  * Teodor Sigaev <teodor@stack.net>
- * $PostgreSQL: pgsql/contrib/ltree/ltree_gist.c,v 1.22 2007/11/16 01:12:24 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/ltree/ltree_gist.c,v 1.22.2.1 2010/02/24 18:02:36 tgl Exp $
  */
 
 #include "ltree.h"
@@ -601,7 +601,7 @@ arrq_cons(ltree_gist * key, ArrayType *_query)
        lquery     *query = (lquery *) ARR_DATA_PTR(_query);
        int                     num = ArrayGetNItems(ARR_NDIM(_query), ARR_DIMS(_query));
 
-       if (ARR_NDIM(_query) != 1)
+       if (ARR_NDIM(_query) > 1)
                ereport(ERROR,
                                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                                 errmsg("array must be one-dimensional")));