On 09/09/2015 01:03 PM, Oskari Saarenmaa wrote:
09.09.2015, 18:53, Andrew Dunstan kirjoitti:
On 09/08/2015 09:54 AM, Andrew Dunstan wrote:
On 09/05/2015 02:47 AM, Oskari Saarenmaa wrote:
There was a long thread about concatenating jsonb objects to each
other, but that discussion didn't touch concatenating other types.
Currently jsonb_concat always just returns the other argument if one
of arguments is considered empty. This causes surprising behavior
when concatenating scalar values to empty arrays:
os=# select '[]'::jsonb || '1'::jsonb;
1
os=# select '[]'::jsonb || '[1]'::jsonb;
[1]
os=# select '[]'::jsonb || '1'::jsonb || '2'::jsonb;
[1, 2]
os=# select '0'::jsonb || '1'::jsonb;
[0, 1]
os=# select '{"x": "y"}'::jsonb || '[1]'::jsonb;
[{"x": "y"}, 1]
os=# select '{"x": "y"}'::jsonb || '1'::jsonb;
ERROR: invalid concatenation of jsonb objects
Attached a patch to fix and test this. Also added a test case for
concatenating two scalar values which currently produces an array..
I'm not sure that behavior makes sense, but didn't want to change
that in this patch as I guess someone could consider that feature
useful.
This looks correct. Barring objection I'll apply this shortly.
Actually, I'm not sure the test is sufficient here. It looks to me like
we should only be taking this fast path if one operand is an empty array
and the other is a non-scalar array.
Otherwise we get things like this (second case is wrong, I think):
andrew=# select '[]'::jsonb || '"a"';
?column?
----------
["a"]
andrew=# select '[]'::jsonb || '{"a":"b"}';
?column?
------------
{"a": "b"}
andrew=# select '[1]'::jsonb || '{"a":"b"}';
?column?
-----------------
[1, {"a": "b"}]
It looks wrong, but I'm not sure what's right in that case. I think
it'd make sense to just restrict concatenation to object || object,
array || array and array || scalar and document that. I doubt many
people expect their objects to turn into arrays if they accidentally
concatenate an array into it. Alternatively the behavior could depend
on the order of arguments for concatenation, array || anything ->
array, object || array -> error.
I don't think I want to change the semantics in general at this stage. A
simple minimal fix to handle the case of the fastpath where one of other
operand is empty, making it entirely consistent with the case where it's
not empty, is attached.
cheers
andrew
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 3b8d42e..154a883 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -3359,12 +3359,18 @@ jsonb_concat(PG_FUNCTION_ARGS)
*it2;
/*
- * If one of the jsonb is empty, just return other.
+ * If one of the jsonb is empty, just return the other if it's not
+ * scalar and both are of the same kind. If it's a scalar or they are
+ * of different kinds we need to perform the concatenation even if one is
+ * empty.
*/
- if (JB_ROOT_COUNT(jb1) == 0)
- PG_RETURN_JSONB(jb2);
- else if (JB_ROOT_COUNT(jb2) == 0)
- PG_RETURN_JSONB(jb1);
+ if (JB_ROOT_IS_OBJECT(jb1) == JB_ROOT_IS_OBJECT(jb2))
+ {
+ if (JB_ROOT_COUNT(jb1) == 0 && !JB_ROOT_IS_SCALAR(jb2))
+ PG_RETURN_JSONB(jb2);
+ else if (JB_ROOT_COUNT(jb2) == 0 && !JB_ROOT_IS_SCALAR(jb1))
+ PG_RETURN_JSONB(jb1);
+ }
it1 = JsonbIteratorInit(&jb1->root);
it2 = JsonbIteratorInit(&jb2->root);
diff --git a/src/test/regress/expected/jsonb.out b/src/test/regress/expected/jsonb.out
index 17656d4..82d1b69 100644
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -2912,6 +2912,42 @@ select '"c"' || '["a", "b"]'::jsonb;
["c", "a", "b"]
(1 row)
+select '[]'::jsonb || '["a"]'::jsonb;
+ ?column?
+----------
+ ["a"]
+(1 row)
+
+select '[]'::jsonb || '"a"'::jsonb;
+ ?column?
+----------
+ ["a"]
+(1 row)
+
+select '"b"'::jsonb || '"a"'::jsonb;
+ ?column?
+------------
+ ["b", "a"]
+(1 row)
+
+select '{}'::jsonb || '{"a":"b"}'::jsonb;
+ ?column?
+------------
+ {"a": "b"}
+(1 row)
+
+select '[]'::jsonb || '{"a":"b"}'::jsonb;
+ ?column?
+--------------
+ [{"a": "b"}]
+(1 row)
+
+select '{"a":"b"}'::jsonb || '[]'::jsonb;
+ ?column?
+--------------
+ [{"a": "b"}]
+(1 row)
+
select '"a"'::jsonb || '{"a":1}';
ERROR: invalid concatenation of jsonb objects
select '{"a":1}' || '"a"'::jsonb;
diff --git a/src/test/regress/expected/jsonb_1.out b/src/test/regress/expected/jsonb_1.out
index 86b1162..2cbc0c7 100644
--- a/src/test/regress/expected/jsonb_1.out
+++ b/src/test/regress/expected/jsonb_1.out
@@ -2912,6 +2912,42 @@ select '"c"' || '["a", "b"]'::jsonb;
["c", "a", "b"]
(1 row)
+select '[]'::jsonb || '["a"]'::jsonb;
+ ?column?
+----------
+ ["a"]
+(1 row)
+
+select '[]'::jsonb || '"a"'::jsonb;
+ ?column?
+----------
+ ["a"]
+(1 row)
+
+select '"b"'::jsonb || '"a"'::jsonb;
+ ?column?
+------------
+ ["b", "a"]
+(1 row)
+
+select '{}'::jsonb || '{"a":"b"}'::jsonb;
+ ?column?
+------------
+ {"a": "b"}
+(1 row)
+
+select '[]'::jsonb || '{"a":"b"}'::jsonb;
+ ?column?
+--------------
+ [{"a": "b"}]
+(1 row)
+
+select '{"a":"b"}'::jsonb || '[]'::jsonb;
+ ?column?
+--------------
+ [{"a": "b"}]
+(1 row)
+
select '"a"'::jsonb || '{"a":1}';
ERROR: invalid concatenation of jsonb objects
select '{"a":1}' || '"a"'::jsonb;
diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql
index 83ed4eb..cb03ada 100644
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -718,6 +718,13 @@ select '["c"]' || '["a", "b"]'::jsonb;
select '["a", "b"]'::jsonb || '"c"';
select '"c"' || '["a", "b"]'::jsonb;
+select '[]'::jsonb || '["a"]'::jsonb;
+select '[]'::jsonb || '"a"'::jsonb;
+select '"b"'::jsonb || '"a"'::jsonb;
+select '{}'::jsonb || '{"a":"b"}'::jsonb;
+select '[]'::jsonb || '{"a":"b"}'::jsonb;
+select '{"a":"b"}'::jsonb || '[]'::jsonb;
+
select '"a"'::jsonb || '{"a":1}';
select '{"a":1}' || '"a"'::jsonb;
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