Revert recent SQL/JSON related commits

Reverts 68222851d5a8, 565caaa79af, and 3a97460970f, because a few
BF animals didn't like one or all of them.

src/backend/executor/execExpr.c

@@ -4414,8 +4414,6 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
 	ErrorSaveContext *escontext =
 		jsexpr->on_error->btype != JSON_BEHAVIOR_ERROR ?
 		&jsestate->escontext : NULL;
-	bool		returning_domain =
-		get_typtype(jsexpr->returning->typid) == TYPTYPE_DOMAIN;
 
 	jsestate->jsexpr = jsexpr;
 
@@ -4558,27 +4556,20 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
 		ExprEvalPushStep(state, scratch);
 	}
 
+	jsestate->jump_empty = jsestate->jump_error = -1;
+
 	/*
 	 * Step to check jsestate->error and return the ON ERROR expression if
 	 * there is one.  This handles both the errors that occur during jsonpath
 	 * evaluation in EEOP_JSONEXPR_PATH and subsequent coercion evaluation.
-	 *
-	 * Speed up common cases by avoiding extra steps for a NULL-valued ON
-	 * ERROR expression unless RETURNING a domain type, where constraints must
-	 * be checked. ExecEvalJsonExprPath() already returns NULL on error,
-	 * making additional steps unnecessary in typical scenarios. Note that the
-	 * default ON ERROR behavior for JSON_VALUE() and JSON_QUERY() is to
-	 * return NULL.
 	 */
-	jsestate->jump_error = state->steps_len;
 	if (jsexpr->on_error &&
-		jsexpr->on_error->btype != JSON_BEHAVIOR_ERROR &&
+		jsexpr->on_error->btype != JSON_BEHAVIOR_ERROR)
-		(!(IsA(jsexpr->on_error->expr, Const) &&
-		   ((Const *) jsexpr->on_error->expr)->constisnull) ||
-		 returning_domain))
 	{
 		ErrorSaveContext *saved_escontext;
 
+		jsestate->jump_error = state->steps_len;
+
 		/* JUMP to end if false, that is, skip the ON ERROR expression. */
 		jumps_to_end = lappend_int(jumps_to_end, state->steps_len);
 		scratch->opcode = EEOP_JUMP_IF_NOT_TRUE;
@@ -4628,19 +4619,14 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state,
 	/*
 	 * Step to check jsestate->empty and return the ON EMPTY expression if
 	 * there is one.
-	 *
-	 * See the comment above for details on the optimization for NULL-valued
-	 * expressions.
 	 */
-	jsestate->jump_empty = state->steps_len;
 	if (jsexpr->on_empty != NULL &&
-		jsexpr->on_empty->btype != JSON_BEHAVIOR_ERROR &&
+		jsexpr->on_empty->btype != JSON_BEHAVIOR_ERROR)
-		(!(IsA(jsexpr->on_empty->expr, Const) &&
-		   ((Const *) jsexpr->on_empty->expr)->constisnull) ||
-		 returning_domain))
 	{
 		ErrorSaveContext *saved_escontext;
 
+		jsestate->jump_empty = state->steps_len;
+
 		/* JUMP to end if false, that is, skip the ON EMPTY expression. */
 		jumps_to_end = lappend_int(jumps_to_end, state->steps_len);
 		scratch->opcode = EEOP_JUMP_IF_NOT_TRUE;

src/backend/parser/parse_expr.c

@@ -4603,13 +4603,13 @@ transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
 			}
 
 			/*
-			 * Assume EMPTY ARRAY ON ERROR when ON ERROR is not specified.
+			 * Assume EMPTY ON ERROR when ON ERROR is not specified.
 			 *
 			 * ON EMPTY cannot be specified at the top level but it can be for
 			 * the individual columns.
 			 */
 			jsexpr->on_error = transformJsonBehavior(pstate, func->on_error,
-													 JSON_BEHAVIOR_EMPTY_ARRAY,
+													 JSON_BEHAVIOR_EMPTY,
 													 jsexpr->returning);
 			break;
 

src/backend/utils/adt/ruleutils.c

@@ -11719,6 +11719,7 @@ get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
 					   bool showimplicit)
 {
 	StringInfo	buf = context->buf;
+	JsonExpr   *jexpr = castNode(JsonExpr, tf->docexpr);
 	ListCell   *lc_colname;
 	ListCell   *lc_coltype;
 	ListCell   *lc_coltypmod;
@@ -11771,10 +11772,6 @@ get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
 		if (ordinality)
 			continue;
 
-		/*
-		 * Set default_behavior to guide get_json_expr_options() on whether to
-		 * to emit the ON ERROR / EMPTY clauses.
-		 */
 		if (colexpr->op == JSON_EXISTS_OP)
 		{
 			appendStringInfoString(buf, " EXISTS");
@@ -11798,6 +11795,9 @@ get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
 			default_behavior = JSON_BEHAVIOR_NULL;
 		}
 
+		if (jexpr->on_error->btype == JSON_BEHAVIOR_ERROR)
+			default_behavior = JSON_BEHAVIOR_ERROR;
+
 		appendStringInfoString(buf, " PATH ");
 
 		get_json_path_spec(colexpr->path_spec, context, showimplicit);
@@ -11875,7 +11875,7 @@ get_json_table(TableFunc *tf, deparse_context *context, bool showimplicit)
 	get_json_table_columns(tf, castNode(JsonTablePathScan, tf->plan), context,
 						   showimplicit);
 
-	if (jexpr->on_error->btype != JSON_BEHAVIOR_EMPTY_ARRAY)
+	if (jexpr->on_error->btype != JSON_BEHAVIOR_EMPTY)
 		get_json_behavior(jexpr->on_error, context, "ERROR");
 
 	if (PRETTY_INDENT(context))

src/test/regress/expected/sqljson_jsontable.out

@@ -1132,46 +1132,3 @@ ERROR:  invalid ON ERROR behavior for column "a"
 LINE 1: ...M JSON_TABLE(jsonb '1', '$' COLUMNS (a int exists empty obje...
                                                              ^
 DETAIL:  Only ERROR, TRUE, FALSE, or UNKNOWN is allowed in ON ERROR for EXISTS columns.
--- Test JSON_TABLE() column deparsing -- don't emit default ON ERROR / EMPTY
--- behavior
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$'));
-                                             QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
- Table Function Scan on "json_table"  (cost=0.01..1.00 rows=100 width=32)
-   Output: a
-   Table Function Call: JSON_TABLE('"a"'::jsonb, '$' AS json_table_path_0 COLUMNS (a text PATH '$'))
-(3 rows)
-
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') ERROR ON ERROR);
-                                                     QUERY PLAN                                                     
---------------------------------------------------------------------------------------------------------------------
- Table Function Scan on "json_table"  (cost=0.01..1.00 rows=100 width=32)
-   Output: a
-   Table Function Call: JSON_TABLE('"a"'::jsonb, '$' AS json_table_path_0 COLUMNS (a text PATH '$') ERROR ON ERROR)
-(3 rows)
-
--- Test JSON_TABLE() deparsing -- don't emit default ON ERROR behavior
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$'));
-                                             QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
- Table Function Scan on "json_table"  (cost=0.01..1.00 rows=100 width=32)
-   Output: a
-   Table Function Call: JSON_TABLE('"a"'::jsonb, '$' AS json_table_path_0 COLUMNS (a text PATH '$'))
-(3 rows)
-
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') EMPTY ON ERROR);
-                                             QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
- Table Function Scan on "json_table"  (cost=0.01..1.00 rows=100 width=32)
-   Output: a
-   Table Function Call: JSON_TABLE('"a"'::jsonb, '$' AS json_table_path_0 COLUMNS (a text PATH '$'))
-(3 rows)
-
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') EMPTY ARRAY ON ERROR);
-                                             QUERY PLAN                                              
------------------------------------------------------------------------------------------------------
- Table Function Scan on "json_table"  (cost=0.01..1.00 rows=100 width=32)
-   Output: a
-   Table Function Call: JSON_TABLE('"a"'::jsonb, '$' AS json_table_path_0 COLUMNS (a text PATH '$'))
-(3 rows)
-

src/test/regress/sql/sqljson_jsontable.sql

@@ -542,13 +542,3 @@ SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int) NULL ON ERROR);
 SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int true on empty));
 SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int omit quotes true on error));
 SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int exists empty object on error));
-
--- Test JSON_TABLE() column deparsing -- don't emit default ON ERROR / EMPTY
--- behavior
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$'));
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') ERROR ON ERROR);
-
--- Test JSON_TABLE() deparsing -- don't emit default ON ERROR behavior
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$'));
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') EMPTY ON ERROR);
-EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') EMPTY ARRAY ON ERROR);