Get rid of unnecessary memory allocation in jsonb_subscript_assign()

akorotkov · akorotkov · commit bb513b364b4f · 2021-02-01T14:06:02.000+03:00
Current code allocates memory for JsonbValue, but it could be placed locally.
diff --git a/src/backend/utils/adt/jsonbsubs.c b/src/backend/utils/adt/jsonbsubs.c
@@ -283,7 +283,7 @@ jsonb_subscript_assign(ExprState *state,
 	 */
 	if (*op->resnull)
 	{
-		JsonbValue *newSource = (JsonbValue *) palloc(sizeof(JsonbValue));
+		JsonbValue	newSource;
 
 		/*
 		 * To avoid any surprising results, set up an empty jsonb array in
@@ -292,17 +292,17 @@ jsonb_subscript_assign(ExprState *state,
 		 */
 		if (workspace->expectArray)
 		{
-			newSource->type = jbvArray;
-			newSource->val.array.nElems = 0;
-			newSource->val.array.rawScalar = false;
+			newSource.type = jbvArray;
+			newSource.val.array.nElems = 0;
+			newSource.val.array.rawScalar = false;
 		}
 		else
 		{
-			newSource->type = jbvObject;
-			newSource->val.object.nPairs = 0;
+			newSource.type = jbvObject;
+			newSource.val.object.nPairs = 0;
 		}
 
-		jsonbSource = JsonbValueToJsonb(newSource);
+		jsonbSource = JsonbValueToJsonb(&newSource);
 		*op->resnull = false;
 	}
 	else

Original file line number	Diff line number	Diff line change
`@@ -283,7 +283,7 @@ jsonb_subscript_assign(ExprState *state,`
`283`	`283`	`*/`
`284`	`284`	`if (*op->resnull)`
`285`	`285`	`{`
`286`		`- JsonbValue newSource = (JsonbValue ) palloc(sizeof(JsonbValue));`
	`286`	`+ JsonbValue newSource;`
`287`	`287`
`288`	`288`	`/*`
`289`	`289`	`* To avoid any surprising results, set up an empty jsonb array in`
`@@ -292,17 +292,17 @@ jsonb_subscript_assign(ExprState *state,`
`292`	`292`	`*/`
`293`	`293`	`if (workspace->expectArray)`
`294`	`294`	`{`
`295`		`- newSource->type = jbvArray;`
`296`		`- newSource->val.array.nElems = 0;`
`297`		`- newSource->val.array.rawScalar = false;`
	`295`	`+ newSource.type = jbvArray;`
	`296`	`+ newSource.val.array.nElems = 0;`
	`297`	`+ newSource.val.array.rawScalar = false;`
`298`	`298`	`}`
`299`	`299`	`else`
`300`	`300`	`{`
`301`		`- newSource->type = jbvObject;`
`302`		`- newSource->val.object.nPairs = 0;`
	`301`	`+ newSource.type = jbvObject;`
	`302`	`+ newSource.val.object.nPairs = 0;`
`303`	`303`	`}`
`304`	`304`
`305`		`- jsonbSource = JsonbValueToJsonb(newSource);`
	`305`	`+ jsonbSource = JsonbValueToJsonb(&newSource);`
`306`	`306`	`*op->resnull = false;`
`307`	`307`	`}`
`308`	`308`	`else`