Add json support for JSON_TABLE

Author: Nikita Glukhov

src/backend/executor/nodeTableFuncscan.c

@@ -23,10 +23,12 @@
 #include "postgres.h"
 
 #include "nodes/execnodes.h"
+#include "catalog/pg_type.h"
 #include "executor/executor.h"
 #include "executor/nodeTableFuncscan.h"
 #include "executor/tablefunc.h"
 #include "miscadmin.h"
+#include "nodes/nodeFuncs.h"
 #include "utils/builtins.h"
 #include "utils/jsonpath.h"
 #include "utils/lsyscache.h"
@@ -164,7 +166,8 @@ ExecInitTableFuncScan(TableFuncScan *node, EState *estate, int eflags)
 
 	/* Only XMLTABLE and JSON_TABLE are supported currently */
 	scanstate->routine =
-		tf->functype == TFT_XMLTABLE ? &XmlTableRoutine : &JsonbTableRoutine;
+		tf->functype == TFT_XMLTABLE ? &XmlTableRoutine :
+		exprType(tf->docexpr) == JSONBOID ? &JsonbTableRoutine : &JsonTableRoutine;
 
 	scanstate->perValueCxt =
 		AllocSetContextCreate(CurrentMemoryContext,

src/backend/parser/parse_expr.c

@@ -4731,12 +4731,6 @@ transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
 			jsexpr->returning.typid = exprType(contextItemExpr);
 			jsexpr->returning.typmod = -1;
 
-			if (jsexpr->returning.typid != JSONBOID)
-				ereport(ERROR,
-						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-						 errmsg("JSON_TABLE() is not yet implemented for json type"),
-						 parser_errposition(pstate, func->location)));
-
 			break;
 	}
 

src/include/utils/jsonpath.h

@@ -314,6 +314,7 @@ extern Datum JsonPathQuery(Datum json, JsonPath *jp, JsonWrapper wrapper,
 
 extern Datum EvalJsonPathVar(void *cxt, bool *isnull);
 
+extern const TableFuncRoutine JsonTableRoutine;
 extern const TableFuncRoutine JsonbTableRoutine;
 
 #endif