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"
@@ -170,7 +172,8 @@ 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

@@ -4595,19 +4595,12 @@ transformJsonFuncExpr(ParseState *pstate, JsonFuncExpr *func)
 				Node	   *expr = jsexpr->formatted_expr ?
 					jsexpr->formatted_expr : jsexpr->raw_expr;
 
-
 				jsexpr->returning.format.type = JS_FORMAT_DEFAULT;
 				jsexpr->returning.format.encoding = JS_ENC_DEFAULT;
 				jsexpr->returning.format.location = -1;
 				jsexpr->returning.typid = exprType(expr);
 				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

@@ -329,6 +329,7 @@ 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