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planner: correct the generation of the field name #11324

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merged 4 commits into from
Jul 23, 2019
Merged

planner: correct the generation of the field name #11324

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e0fbef2
planner: correct the generation of the field name
winoros Jul 18, 2019
39f3679
Merge branch 'master' into fix-column-name
winoros Jul 19, 2019
68dac1b
Merge branch 'master' into fix-column-name
zz-jason Jul 23, 2019
681d036
Merge branch 'master' into fix-column-name
winoros Jul 23, 2019
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7 changes: 7 additions & 0 deletions executor/executor_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2205,6 +2205,13 @@ func (s *testSuite) TestColumnName(c *C) {
c.Assert(fields[1].ColumnAsName.L, Equals, "num")
tk.MustExec("set @@tidb_enable_window_function = 0")
rs.Close()

rs, err = tk.Exec("select if(1,c,c) from t;")
c.Check(err, IsNil)
fields = rs.Fields()
c.Assert(fields[0].Column.Name.L, Equals, "if(1,c,c)")
// It's a compatibility issue. Should be empty instead.
c.Assert(fields[0].ColumnAsName.L, Equals, "if(1,c,c)")
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This comptibility issue is separated work. #11323

}

func (s *testSuite) TestSelectVar(c *C) {
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18 changes: 10 additions & 8 deletions planner/core/logical_plan_builder.go
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Expand Up @@ -591,12 +591,10 @@ func (b *PlanBuilder) buildSelection(p LogicalPlan, where ast.ExprNode, AggMappe
}

// buildProjectionFieldNameFromColumns builds the field name, table name and database name when field expression is a column reference.
func (b *PlanBuilder) buildProjectionFieldNameFromColumns(field *ast.SelectField, c *expression.Column) (colName, origColName, tblName, origTblName, dbName model.CIStr) {
if astCol, ok := getInnerFromParenthesesAndUnaryPlus(field.Expr).(*ast.ColumnNameExpr); ok {
origColName, tblName, dbName = astCol.Name.Name, astCol.Name.Table, astCol.Name.Schema
}
if field.AsName.L != "" {
colName = field.AsName
func (b *PlanBuilder) buildProjectionFieldNameFromColumns(origField *ast.SelectField, colNameField *ast.ColumnNameExpr, c *expression.Column) (colName, origColName, tblName, origTblName, dbName model.CIStr) {
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Can we set Schema and Table for ColumnNameExpr when building expression.Column from it? Thus we can remove c here which will make the code clearer.

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I prefer not to change the ast's content 😂

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It will not be changed.
Check /~https://github.com/pingcap/tidb/blob/master/planner/core/logical_plan_builder.go#L2119

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No, if there's no wild star. It's the original content.

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But we can create a new ast.ColumnNameExpr here?
/~https://github.com/pingcap/tidb/blob/master/planner/core/logical_plan_builder.go#L1889

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I think we don't need to change it for now. The logic of creating the field names will be rewritten in the following PRs.

origColName, tblName, dbName = colNameField.Name.Name, colNameField.Name.Table, colNameField.Name.Schema
if origField.AsName.L != "" {
colName = origField.AsName
} else {
colName = origColName
}
Expand Down Expand Up @@ -677,9 +675,13 @@ func (b *PlanBuilder) buildProjectionFieldNameFromExpressions(field *ast.SelectF
// buildProjectionField builds the field object according to SelectField in projection.
func (b *PlanBuilder) buildProjectionField(id, position int, field *ast.SelectField, expr expression.Expression) (*expression.Column, error) {
var origTblName, tblName, origColName, colName, dbName model.CIStr
if c, ok := expr.(*expression.Column); ok && !c.IsReferenced {
innerNode := getInnerFromParenthesesAndUnaryPlus(field.Expr)
col, isCol := expr.(*expression.Column)
// Correlated column won't affect the final output names. So we can put it in any of the three logic block.
// Don't put it into the first block just for simplifying the codes.
if colNameField, ok := innerNode.(*ast.ColumnNameExpr); ok && isCol {
// Field is a column reference.
colName, origColName, tblName, origTblName, dbName = b.buildProjectionFieldNameFromColumns(field, c)
colName, origColName, tblName, origTblName, dbName = b.buildProjectionFieldNameFromColumns(field, colNameField, col)
} else if field.AsName.L != "" {
// Field has alias.
colName = field.AsName
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