5 files changed, 42 insertions, 0 deletions
diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 0d3e1121cd0..1d63abc11b9 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -3658,6 +3658,12 @@ populate_recordset_worker(FunctionCallInfo fcinfo, const char *funcname,
 	if (PG_ARGISNULL(json_arg_num))
 		PG_RETURN_NULL();
 
+	/*
+	 * Forcibly update the cached tupdesc, to ensure we have the right tupdesc
+	 * to return even if the JSON contains no rows.
+	 */
+	update_cached_tupdesc(&cache->c.io.composite, cache->fn_mcxt);
+
 	state = palloc0(sizeof(PopulateRecordsetState));
 
 	/* make tuplestore in a sufficiently long-lived memory context */
diff --git a/src/test/regress/expected/json.out b/src/test/regress/expected/json.out
index 6020feeea41..ea1be61effc 100644
--- a/src/test/regress/expected/json.out
+++ b/src/test/regress/expected/json.out
@@ -1851,6 +1851,19 @@ FROM (VALUES (1),(2)) v(i);
  2 | (2,43)
 (4 rows)
 
+-- empty array is a corner case
+SELECT json_populate_recordset(null::record, '[]');
+ERROR:  record type has not been registered
+SELECT json_populate_recordset(row(1,2), '[]');
+ json_populate_recordset 
+-------------------------
+(0 rows)
+
+SELECT * FROM json_populate_recordset(NULL::jpop,'[]') q;
+ a | b | c 
+---+---+---
+(0 rows)
+
 -- composite domain
 SELECT json_populate_recordset(null::j_ordered_pair, '[{"x": 0, "y": 1}]');
  json_populate_recordset 
diff --git a/src/test/regress/expected/jsonb.out b/src/test/regress/expected/jsonb.out
index f045e085384..4fddd2de140 100644
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -2533,6 +2533,19 @@ FROM (VALUES (1),(2)) v(i);
  2 | (2,43)
 (4 rows)
 
+-- empty array is a corner case
+SELECT jsonb_populate_recordset(null::record, '[]');
+ERROR:  record type has not been registered
+SELECT jsonb_populate_recordset(row(1,2), '[]');
+ jsonb_populate_recordset 
+--------------------------
+(0 rows)
+
+SELECT * FROM jsonb_populate_recordset(NULL::jbpop,'[]') q;
+ a | b | c 
+---+---+---
+(0 rows)
+
 -- composite domain
 SELECT jsonb_populate_recordset(null::jb_ordered_pair, '[{"x": 0, "y": 1}]');
  jsonb_populate_recordset 
diff --git a/src/test/regress/sql/json.sql b/src/test/regress/sql/json.sql
index 97c75420e9c..d1e40084277 100644
--- a/src/test/regress/sql/json.sql
+++ b/src/test/regress/sql/json.sql
@@ -550,6 +550,11 @@ SELECT json_populate_recordset(row(1,2), '[{"f1": 0, "f2": 1}]');
 SELECT i, json_populate_recordset(row(i,50), '[{"f1":"42"},{"f2":"43"}]')
 FROM (VALUES (1),(2)) v(i);
 
+-- empty array is a corner case
+SELECT json_populate_recordset(null::record, '[]');
+SELECT json_populate_recordset(row(1,2), '[]');
+SELECT * FROM json_populate_recordset(NULL::jpop,'[]') q;
+
 -- composite domain
 SELECT json_populate_recordset(null::j_ordered_pair, '[{"x": 0, "y": 1}]');
 SELECT json_populate_recordset(row(1,2)::j_ordered_pair, '[{"x": 0}, {"y": 3}]');
diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql
index bd82fd13f7d..6cbdfe43958 100644
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -666,6 +666,11 @@ SELECT jsonb_populate_recordset(row(1,2), '[{"f1": 0, "f2": 1}]');
 SELECT i, jsonb_populate_recordset(row(i,50), '[{"f1":"42"},{"f2":"43"}]')
 FROM (VALUES (1),(2)) v(i);
 
+-- empty array is a corner case
+SELECT jsonb_populate_recordset(null::record, '[]');
+SELECT jsonb_populate_recordset(row(1,2), '[]');
+SELECT * FROM jsonb_populate_recordset(NULL::jbpop,'[]') q;
+
 -- composite domain
 SELECT jsonb_populate_recordset(null::jb_ordered_pair, '[{"x": 0, "y": 1}]');
 SELECT jsonb_populate_recordset(row(1,2)::jb_ordered_pair, '[{"x": 0}, {"y": 3}]');