From 30e21a4f9bb2ef1c337bf0810374f3b2b4dc5166 Mon Sep 17 00:00:00 2001 From: Olga Shestopalova Date: Tue, 26 Sep 2023 08:18:40 -0400 Subject: [PATCH] add comment explaining the code Signed-off-by: Olga Shestopalova --- .../tabletmanager/vreplication/table_plan_builder.go | 7 ++++++- go/vt/vttablet/tabletserver/vstreamer/planbuilder.go | 7 ++++++- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/go/vt/vttablet/tabletmanager/vreplication/table_plan_builder.go b/go/vt/vttablet/tabletmanager/vreplication/table_plan_builder.go index 0acd0f398cc..da1b4dfc2f3 100644 --- a/go/vt/vttablet/tabletmanager/vreplication/table_plan_builder.go +++ b/go/vt/vttablet/tabletmanager/vreplication/table_plan_builder.go @@ -425,6 +425,11 @@ func (tpb *tablePlanBuilder) analyzeExpr(selExpr sqlparser.SelectExpr) (*colExpr references: make(map[string]bool), } if expr, ok := aliased.Expr.(*sqlparser.ConvertUsingExpr); ok { + // Here we find the actual column name in the convert, in case + // this is a column rename and the AS is the new column. + // For example, in convert(c1 using utf8mb4) as c2, we want to find + // c1, because c1 exists in the current table whereas c2 is the renamed column + // in the desired table. var colName sqlparser.IdentifierCI err := sqlparser.Walk(func(node sqlparser.SQLNode) (kontinue bool, err error) { switch node := node.(type) { @@ -437,7 +442,7 @@ func (tpb *tablePlanBuilder) analyzeExpr(selExpr sqlparser.SelectExpr) (*colExpr return true, nil }, aliased.Expr) if err != nil { - return nil, fmt.Errorf("failed to find column name for convert using expression: %v", sqlparser.String(aliased.Expr)) + return nil, fmt.Errorf("failed to find column name for convert using expression: %v, %v", sqlparser.String(aliased.Expr), err) } selExpr := &sqlparser.ConvertUsingExpr{ Type: "utf8mb4", diff --git a/go/vt/vttablet/tabletserver/vstreamer/planbuilder.go b/go/vt/vttablet/tabletserver/vstreamer/planbuilder.go index ff81d8b1b01..c9bb0121571 100644 --- a/go/vt/vttablet/tabletserver/vstreamer/planbuilder.go +++ b/go/vt/vttablet/tabletserver/vstreamer/planbuilder.go @@ -727,6 +727,11 @@ func (plan *Plan) analyzeExpr(vschema *localVSchema, selExpr sqlparser.SelectExp FixedValue: sqltypes.NewInt64(num), }, nil case *sqlparser.ConvertUsingExpr: + // Here we find the actual column name in the convert, in case + // this is a column rename and the AS is the new column. + // For example, in convert(c1 using utf8mb4) as c2, we want to find + // c1, because c1 exists in the current table whereas c2 is the renamed column + // in the desired table. var colName sqlparser.IdentifierCI err := sqlparser.Walk(func(node sqlparser.SQLNode) (kontinue bool, err error) { switch node := node.(type) { @@ -739,7 +744,7 @@ func (plan *Plan) analyzeExpr(vschema *localVSchema, selExpr sqlparser.SelectExp return true, nil }, aliased.Expr) if err != nil { - return ColExpr{}, fmt.Errorf("failed to find column name for convert using expression: %v", sqlparser.String(aliased.Expr)) + return ColExpr{}, fmt.Errorf("failed to find column name for convert using expression: %v, %v", sqlparser.String(aliased.Expr), err) } colnum, err := findColumn(plan.Table, colName) if err != nil {