Merge pull request #8871 from planetscale/information-schema-bug

fix merging dba query as a subquery both in v3 and gen4
vitessio · Sep 23, 2021 · 8bfcf5c · 8bfcf5c
2 parents b04726d + 5887a34
commit 8bfcf5c
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Showing 3 changed files with 74 additions and 2 deletions.
diff --git a/go/vt/vtgate/planbuilder/route.go b/go/vt/vtgate/planbuilder/route.go
@@ -394,6 +394,18 @@ func (rb *route) Inputs() []logicalPlan {
 // with the outer route.
 func (rb *route) MergeSubquery(pb *primitiveBuilder, inner *route) bool {
 	if rb.SubqueryCanMerge(pb, inner) {
+		if inner.eroute.Opcode == engine.SelectDBA && (len(inner.eroute.SysTableTableName) > 0 || len(inner.eroute.SysTableTableSchema) > 0) {
+			switch rb.eroute.Opcode {
+			case engine.SelectDBA, engine.SelectReference:
+				rb.eroute.SysTableTableSchema = append(rb.eroute.SysTableTableSchema, inner.eroute.SysTableTableSchema...)
+				for k, v := range inner.eroute.SysTableTableName {
+					rb.eroute.SysTableTableName[k] = v
+				}
+				rb.eroute.Opcode = engine.SelectDBA
+			default:
+				return false
+			}
+		}
 		rb.substitutions = append(rb.substitutions, inner.substitutions...)
 		inner.Redirect = rb
 		return true

diff --git a/go/vt/vtgate/planbuilder/route_planning.go b/go/vt/vtgate/planbuilder/route_planning.go
@@ -150,7 +150,7 @@ func optimizeSubQuery(ctx *planningContext, op *abstract.SubQuery) (queryTree, e
 
 		preds := inner.Inner.UnsolvedPredicates(ctx.semTable)
 		merger := func(a, b *routeTree) (*routeTree, error) {
-			return mergeSubQuery(ctx, a, inner)
+			return mergeSubQuery(ctx, a, b, inner)
 		}
 
 		merged, err := tryMergeSubQuery(ctx, outerTree, treeInner, inner, preds, merger)
@@ -279,7 +279,7 @@ func rewriteSubqueryDependenciesForJoin(ctx *planningContext, otherTree queryTre
 	return rewriteError
 }
 
-func mergeSubQuery(ctx *planningContext, outer *routeTree, subq *abstract.SubQueryInner) (*routeTree, error) {
+func mergeSubQuery(ctx *planningContext, outer *routeTree, inner *routeTree, subq *abstract.SubQueryInner) (*routeTree, error) {
 	ctx.sqToReplace[subq.ArgName] = subq.SelectStatement
 	// go over the subquery and add its tables to the one's solved by the route it is merged with
 	// this is needed to so that later when we try to push projections, we get the correct
@@ -294,6 +294,11 @@ func mergeSubQuery(ctx *planningContext, outer *routeTree, subq *abstract.SubQue
 	if err != nil {
 		return nil, err
 	}
+	outer.SysTableTableSchema = append(outer.SysTableTableSchema, inner.SysTableTableSchema...)
+	for k, v := range inner.SysTableTableName {
+		outer.SysTableTableName[k] = v
+	}
+
 	err = outer.resetRoutingSelections(ctx)
 	if err != nil {
 		return nil, err

diff --git a/go/vt/vtgate/planbuilder/testdata/sysschema_default.txt b/go/vt/vtgate/planbuilder/testdata/sysschema_default.txt
@@ -51,3 +51,58 @@ Gen4 plan same as above
     "Table": "information_schema.`columns`, information_schema.`tables`"
   }
 }
+
+# system schema query as a subquery
+"SELECT (SELECT 1 FROM information_schema.schemata WHERE schema_name='MyDatabase' LIMIT 1);"
+{
+  "QueryType": "SELECT",
+  "Original": "SELECT (SELECT 1 FROM information_schema.schemata WHERE schema_name='MyDatabase' LIMIT 1);",
+  "Instructions": {
+    "OperatorType": "Route",
+    "Variant": "SelectDBA",
+    "Keyspace": {
+      "Name": "main",
+      "Sharded": false
+    },
+    "FieldQuery": "select (select 1 from information_schema.schemata where 1 != 1) from dual where 1 != 1",
+    "Query": "select (select 1 from information_schema.schemata where schema_name = :__vtschemaname limit 1) from dual",
+    "SysTableTableSchema": "[VARBINARY(\"MyDatabase\")]",
+    "Table": "dual"
+  }
+}
+Gen4 plan same as above
+
+# system schema query as a derived table
+"SELECT * from (SELECT 1 FROM information_schema.schemata WHERE schema_name='MyDatabase' LIMIT 1) x"
+{
+  "QueryType": "SELECT",
+  "Original": "SELECT * from (SELECT 1 FROM information_schema.schemata WHERE schema_name='MyDatabase' LIMIT 1) x",
+  "Instructions": {
+    "OperatorType": "Route",
+    "Variant": "SelectDBA",
+    "Keyspace": {
+      "Name": "main",
+      "Sharded": false
+    },
+    "FieldQuery": "select * from (select 1 from information_schema.schemata where 1 != 1) as x where 1 != 1",
+    "Query": "select * from (select 1 from information_schema.schemata where schema_name = :__vtschemaname limit 1) as x",
+    "SysTableTableSchema": "[VARBINARY(\"MyDatabase\")]",
+    "Table": "information_schema.schemata"
+  }
+}
+{
+  "QueryType": "SELECT",
+  "Original": "SELECT * from (SELECT 1 FROM information_schema.schemata WHERE schema_name='MyDatabase' LIMIT 1) x",
+  "Instructions": {
+    "OperatorType": "Route",
+    "Variant": "SelectDBA",
+    "Keyspace": {
+      "Name": "main",
+      "Sharded": false
+    },
+    "FieldQuery": "select x.`1` from (select 1 from information_schema.schemata where 1 != 1) as x where 1 != 1",
+    "Query": "select x.`1` from (select 1 from information_schema.schemata where schema_name = :__vtschemaname limit 1) as x",
+    "SysTableTableSchema": "[VARBINARY(\"MyDatabase\")]",
+    "Table": "information_schema.schemata"
+  }
+}