gitroast/vendor/github.com/pingcap/tidb/optimizer/resolver.go

925 lines
28 KiB
Go

// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package optimizer
import (
"fmt"
"github.com/juju/errors"
"github.com/pingcap/tidb/ast"
"github.com/pingcap/tidb/column"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/infoschema"
"github.com/pingcap/tidb/model"
"github.com/pingcap/tidb/mysql"
"github.com/pingcap/tidb/sessionctx/db"
"github.com/pingcap/tidb/util/types"
)
// ResolveName resolves table name and column name.
// It generates ResultFields for ResultSetNode and resolves ColumnNameExpr to a ResultField.
func ResolveName(node ast.Node, info infoschema.InfoSchema, ctx context.Context) error {
defaultSchema := db.GetCurrentSchema(ctx)
resolver := nameResolver{Info: info, Ctx: ctx, DefaultSchema: model.NewCIStr(defaultSchema)}
node.Accept(&resolver)
return errors.Trace(resolver.Err)
}
// nameResolver is the visitor to resolve table name and column name.
// In general, a reference can only refer to information that are available for it.
// So children elements are visited in the order that previous elements make information
// available for following elements.
//
// During visiting, information are collected and stored in resolverContext.
// When we enter a subquery, a new resolverContext is pushed to the contextStack, so subquery
// information can overwrite outer query information. When we look up for a column reference,
// we look up from top to bottom in the contextStack.
type nameResolver struct {
Info infoschema.InfoSchema
Ctx context.Context
DefaultSchema model.CIStr
Err error
useOuterContext bool
contextStack []*resolverContext
}
// resolverContext stores information in a single level of select statement
// that table name and column name can be resolved.
type resolverContext struct {
/* For Select Statement. */
// table map to lookup and check table name conflict.
tableMap map[string]int
// table map to lookup and check derived-table(subselect) name conflict.
derivedTableMap map[string]int
// tableSources collected in from clause.
tables []*ast.TableSource
// result fields collected in select field list.
fieldList []*ast.ResultField
// result fields collected in group by clause.
groupBy []*ast.ResultField
// The join node stack is used by on condition to find out
// available tables to reference. On condition can only
// refer to tables involved in current join.
joinNodeStack []*ast.Join
// When visiting TableRefs, tables in this context are not available
// because it is being collected.
inTableRefs bool
// When visiting on conditon only tables in current join node are available.
inOnCondition bool
// When visiting field list, fieldList in this context are not available.
inFieldList bool
// When visiting group by, groupBy fields are not available.
inGroupBy bool
// When visiting having, only fieldList and groupBy fields are available.
inHaving bool
// When visiting having, checks if the expr is an aggregate function expr.
inHavingAgg bool
// OrderBy clause has different resolving rule than group by.
inOrderBy bool
// When visiting column name in ByItem, we should know if the column name is in an expression.
inByItemExpression bool
// If subquery use outer context.
useOuterContext bool
// When visiting multi-table delete stmt table list.
inDeleteTableList bool
// When visiting create/drop table statement.
inCreateOrDropTable bool
// When visiting show statement.
inShow bool
}
// currentContext gets the current resolverContext.
func (nr *nameResolver) currentContext() *resolverContext {
stackLen := len(nr.contextStack)
if stackLen == 0 {
return nil
}
return nr.contextStack[stackLen-1]
}
// pushContext is called when we enter a statement.
func (nr *nameResolver) pushContext() {
nr.contextStack = append(nr.contextStack, &resolverContext{
tableMap: map[string]int{},
derivedTableMap: map[string]int{},
})
}
// popContext is called when we leave a statement.
func (nr *nameResolver) popContext() {
nr.contextStack = nr.contextStack[:len(nr.contextStack)-1]
}
// pushJoin is called when we enter a join node.
func (nr *nameResolver) pushJoin(j *ast.Join) {
ctx := nr.currentContext()
ctx.joinNodeStack = append(ctx.joinNodeStack, j)
}
// popJoin is called when we leave a join node.
func (nr *nameResolver) popJoin() {
ctx := nr.currentContext()
ctx.joinNodeStack = ctx.joinNodeStack[:len(ctx.joinNodeStack)-1]
}
// Enter implements ast.Visitor interface.
func (nr *nameResolver) Enter(inNode ast.Node) (outNode ast.Node, skipChildren bool) {
switch v := inNode.(type) {
case *ast.AdminStmt:
nr.pushContext()
case *ast.AggregateFuncExpr:
ctx := nr.currentContext()
if ctx.inHaving {
ctx.inHavingAgg = true
}
case *ast.AlterTableStmt:
nr.pushContext()
case *ast.ByItem:
if _, ok := v.Expr.(*ast.ColumnNameExpr); !ok {
// If ByItem is not a single column name expression,
// the resolving rule is different from order by clause.
nr.currentContext().inByItemExpression = true
}
if nr.currentContext().inGroupBy {
// make sure item is not aggregate function
if ast.HasAggFlag(v.Expr) {
nr.Err = ErrInvalidGroupFuncUse
return inNode, true
}
}
case *ast.CreateIndexStmt:
nr.pushContext()
case *ast.CreateTableStmt:
nr.pushContext()
nr.currentContext().inCreateOrDropTable = true
case *ast.DeleteStmt:
nr.pushContext()
case *ast.DeleteTableList:
nr.currentContext().inDeleteTableList = true
case *ast.DoStmt:
nr.pushContext()
case *ast.DropTableStmt:
nr.pushContext()
nr.currentContext().inCreateOrDropTable = true
case *ast.DropIndexStmt:
nr.pushContext()
case *ast.FieldList:
nr.currentContext().inFieldList = true
case *ast.GroupByClause:
nr.currentContext().inGroupBy = true
case *ast.HavingClause:
nr.currentContext().inHaving = true
case *ast.InsertStmt:
nr.pushContext()
case *ast.Join:
nr.pushJoin(v)
case *ast.OnCondition:
nr.currentContext().inOnCondition = true
case *ast.OrderByClause:
nr.currentContext().inOrderBy = true
case *ast.SelectStmt:
nr.pushContext()
case *ast.SetStmt:
for _, assign := range v.Variables {
if cn, ok := assign.Value.(*ast.ColumnNameExpr); ok && cn.Name.Table.L == "" {
// Convert column name expression to string value expression.
assign.Value = ast.NewValueExpr(cn.Name.Name.O)
}
}
nr.pushContext()
case *ast.ShowStmt:
nr.pushContext()
nr.currentContext().inShow = true
nr.fillShowFields(v)
case *ast.TableRefsClause:
nr.currentContext().inTableRefs = true
case *ast.TruncateTableStmt:
nr.pushContext()
case *ast.UnionStmt:
nr.pushContext()
case *ast.UpdateStmt:
nr.pushContext()
}
return inNode, false
}
// Leave implements ast.Visitor interface.
func (nr *nameResolver) Leave(inNode ast.Node) (node ast.Node, ok bool) {
switch v := inNode.(type) {
case *ast.AdminStmt:
nr.popContext()
case *ast.AggregateFuncExpr:
ctx := nr.currentContext()
if ctx.inHaving {
ctx.inHavingAgg = false
}
case *ast.AlterTableStmt:
nr.popContext()
case *ast.TableName:
nr.handleTableName(v)
case *ast.ColumnNameExpr:
nr.handleColumnName(v)
case *ast.CreateIndexStmt:
nr.popContext()
case *ast.CreateTableStmt:
nr.popContext()
case *ast.DeleteTableList:
nr.currentContext().inDeleteTableList = false
case *ast.DoStmt:
nr.popContext()
case *ast.DropIndexStmt:
nr.popContext()
case *ast.DropTableStmt:
nr.popContext()
case *ast.TableSource:
nr.handleTableSource(v)
case *ast.OnCondition:
nr.currentContext().inOnCondition = false
case *ast.Join:
nr.handleJoin(v)
nr.popJoin()
case *ast.TableRefsClause:
nr.currentContext().inTableRefs = false
case *ast.FieldList:
nr.handleFieldList(v)
nr.currentContext().inFieldList = false
case *ast.GroupByClause:
ctx := nr.currentContext()
ctx.inGroupBy = false
for _, item := range v.Items {
switch x := item.Expr.(type) {
case *ast.ColumnNameExpr:
ctx.groupBy = append(ctx.groupBy, x.Refer)
}
}
case *ast.HavingClause:
nr.currentContext().inHaving = false
case *ast.OrderByClause:
nr.currentContext().inOrderBy = false
case *ast.ByItem:
nr.currentContext().inByItemExpression = false
case *ast.PositionExpr:
nr.handlePosition(v)
case *ast.SelectStmt:
ctx := nr.currentContext()
v.SetResultFields(ctx.fieldList)
if ctx.useOuterContext {
nr.useOuterContext = true
}
nr.popContext()
case *ast.SetStmt:
nr.popContext()
case *ast.ShowStmt:
nr.popContext()
case *ast.SubqueryExpr:
if nr.useOuterContext {
// TODO: check this
// If there is a deep nest of subquery, there may be something wrong.
v.UseOuterContext = true
nr.useOuterContext = false
}
case *ast.TruncateTableStmt:
nr.popContext()
case *ast.UnionStmt:
ctx := nr.currentContext()
v.SetResultFields(ctx.fieldList)
if ctx.useOuterContext {
nr.useOuterContext = true
}
nr.popContext()
case *ast.UnionSelectList:
nr.handleUnionSelectList(v)
case *ast.InsertStmt:
nr.popContext()
case *ast.DeleteStmt:
nr.popContext()
case *ast.UpdateStmt:
nr.popContext()
}
return inNode, nr.Err == nil
}
// handleTableName looks up and sets the schema information and result fields for table name.
func (nr *nameResolver) handleTableName(tn *ast.TableName) {
if tn.Schema.L == "" {
tn.Schema = nr.DefaultSchema
}
ctx := nr.currentContext()
if ctx.inCreateOrDropTable {
// The table may not exist in create table or drop table statement.
// Skip resolving the table to avoid error.
return
}
if ctx.inDeleteTableList {
idx, ok := ctx.tableMap[nr.tableUniqueName(tn.Schema, tn.Name)]
if !ok {
nr.Err = errors.Errorf("Unknown table %s", tn.Name.O)
return
}
ts := ctx.tables[idx]
tableName := ts.Source.(*ast.TableName)
tn.DBInfo = tableName.DBInfo
tn.TableInfo = tableName.TableInfo
tn.SetResultFields(tableName.GetResultFields())
return
}
table, err := nr.Info.TableByName(tn.Schema, tn.Name)
if err != nil {
nr.Err = errors.Trace(err)
return
}
tn.TableInfo = table.Meta()
dbInfo, _ := nr.Info.SchemaByName(tn.Schema)
tn.DBInfo = dbInfo
rfs := make([]*ast.ResultField, 0, len(tn.TableInfo.Columns))
for _, v := range tn.TableInfo.Columns {
if v.State != model.StatePublic {
continue
}
expr := &ast.ValueExpr{}
expr.SetType(&v.FieldType)
rf := &ast.ResultField{
Column: v,
Table: tn.TableInfo,
DBName: tn.Schema,
Expr: expr,
TableName: tn,
}
rfs = append(rfs, rf)
}
tn.SetResultFields(rfs)
return
}
// handleTableSources checks name duplication
// and puts the table source in current resolverContext.
// Note:
// "select * from t as a join (select 1) as a;" is not duplicate.
// "select * from t as a join t as a;" is duplicate.
// "select * from (select 1) as a join (select 1) as a;" is duplicate.
func (nr *nameResolver) handleTableSource(ts *ast.TableSource) {
for _, v := range ts.GetResultFields() {
v.TableAsName = ts.AsName
}
ctx := nr.currentContext()
switch ts.Source.(type) {
case *ast.TableName:
var name string
if ts.AsName.L != "" {
name = ts.AsName.L
} else {
tableName := ts.Source.(*ast.TableName)
name = nr.tableUniqueName(tableName.Schema, tableName.Name)
}
if _, ok := ctx.tableMap[name]; ok {
nr.Err = errors.Errorf("duplicated table/alias name %s", name)
return
}
ctx.tableMap[name] = len(ctx.tables)
case *ast.SelectStmt:
name := ts.AsName.L
if _, ok := ctx.derivedTableMap[name]; ok {
nr.Err = errors.Errorf("duplicated table/alias name %s", name)
return
}
ctx.derivedTableMap[name] = len(ctx.tables)
}
dupNames := make(map[string]struct{}, len(ts.GetResultFields()))
for _, f := range ts.GetResultFields() {
// duplicate column name in one table is not allowed.
// "select * from (select 1, 1) as a;" is duplicate.
name := f.ColumnAsName.L
if name == "" {
name = f.Column.Name.L
}
if _, ok := dupNames[name]; ok {
nr.Err = errors.Errorf("Duplicate column name '%s'", name)
return
}
dupNames[name] = struct{}{}
}
ctx.tables = append(ctx.tables, ts)
return
}
// handleJoin sets result fields for join.
func (nr *nameResolver) handleJoin(j *ast.Join) {
if j.Right == nil {
j.SetResultFields(j.Left.GetResultFields())
return
}
leftLen := len(j.Left.GetResultFields())
rightLen := len(j.Right.GetResultFields())
rfs := make([]*ast.ResultField, leftLen+rightLen)
copy(rfs, j.Left.GetResultFields())
copy(rfs[leftLen:], j.Right.GetResultFields())
j.SetResultFields(rfs)
}
// handleColumnName looks up and sets ResultField for
// the column name.
func (nr *nameResolver) handleColumnName(cn *ast.ColumnNameExpr) {
ctx := nr.currentContext()
if ctx.inOnCondition {
// In on condition, only tables within current join is available.
nr.resolveColumnNameInOnCondition(cn)
return
}
// Try to resolve the column name form top to bottom in the context stack.
for i := len(nr.contextStack) - 1; i >= 0; i-- {
if nr.resolveColumnNameInContext(nr.contextStack[i], cn) {
// Column is already resolved or encountered an error.
if i < len(nr.contextStack)-1 {
// If in subselect, the query use outer query.
nr.currentContext().useOuterContext = true
}
return
}
}
nr.Err = errors.Errorf("unknown column %s", cn.Name.Name.L)
}
// resolveColumnNameInContext looks up and sets ResultField for a column with the ctx.
func (nr *nameResolver) resolveColumnNameInContext(ctx *resolverContext, cn *ast.ColumnNameExpr) bool {
if ctx.inTableRefs {
// In TableRefsClause, column reference only in join on condition which is handled before.
return false
}
if ctx.inFieldList {
// only resolve column using tables.
return nr.resolveColumnInTableSources(cn, ctx.tables)
}
if ctx.inGroupBy {
// From tables first, then field list.
// If ctx.InByItemExpression is true, the item is not an identifier.
// Otherwise it is an identifier.
if ctx.inByItemExpression {
// From table first, then field list.
if nr.resolveColumnInTableSources(cn, ctx.tables) {
return true
}
found := nr.resolveColumnInResultFields(ctx, cn, ctx.fieldList)
if nr.Err == nil && found {
// Check if resolved refer is an aggregate function expr.
if _, ok := cn.Refer.Expr.(*ast.AggregateFuncExpr); ok {
nr.Err = ErrIllegalReference.Gen("Reference '%s' not supported (reference to group function)", cn.Name.Name.O)
}
}
return found
}
// Resolve from table first, then from select list.
found := nr.resolveColumnInTableSources(cn, ctx.tables)
if nr.Err != nil {
return found
}
// We should copy the refer here.
// Because if the ByItem is an identifier, we should check if it
// is ambiguous even it is already resolved from table source.
// If the ByItem is not an identifier, we do not need the second check.
r := cn.Refer
if nr.resolveColumnInResultFields(ctx, cn, ctx.fieldList) {
if nr.Err != nil {
return true
}
if r != nil {
// It is not ambiguous and already resolved from table source.
// We should restore its Refer.
cn.Refer = r
}
if _, ok := cn.Refer.Expr.(*ast.AggregateFuncExpr); ok {
nr.Err = ErrIllegalReference.Gen("Reference '%s' not supported (reference to group function)", cn.Name.Name.O)
}
return true
}
return found
}
if ctx.inHaving {
// First group by, then field list.
if nr.resolveColumnInResultFields(ctx, cn, ctx.groupBy) {
return true
}
if ctx.inHavingAgg {
// If cn is in an aggregate function in having clause, check tablesource first.
if nr.resolveColumnInTableSources(cn, ctx.tables) {
return true
}
}
return nr.resolveColumnInResultFields(ctx, cn, ctx.fieldList)
}
if ctx.inOrderBy {
if nr.resolveColumnInResultFields(ctx, cn, ctx.groupBy) {
return true
}
if ctx.inByItemExpression {
// From table first, then field list.
if nr.resolveColumnInTableSources(cn, ctx.tables) {
return true
}
return nr.resolveColumnInResultFields(ctx, cn, ctx.fieldList)
}
// Field list first, then from table.
if nr.resolveColumnInResultFields(ctx, cn, ctx.fieldList) {
return true
}
return nr.resolveColumnInTableSources(cn, ctx.tables)
}
if ctx.inShow {
return nr.resolveColumnInResultFields(ctx, cn, ctx.fieldList)
}
// In where clause.
return nr.resolveColumnInTableSources(cn, ctx.tables)
}
// resolveColumnNameInOnCondition resolves the column name in current join.
func (nr *nameResolver) resolveColumnNameInOnCondition(cn *ast.ColumnNameExpr) {
ctx := nr.currentContext()
join := ctx.joinNodeStack[len(ctx.joinNodeStack)-1]
tableSources := appendTableSources(nil, join)
if !nr.resolveColumnInTableSources(cn, tableSources) {
nr.Err = errors.Errorf("unkown column name %s", cn.Name.Name.O)
}
}
func (nr *nameResolver) resolveColumnInTableSources(cn *ast.ColumnNameExpr, tableSources []*ast.TableSource) (done bool) {
var matchedResultField *ast.ResultField
tableNameL := cn.Name.Table.L
columnNameL := cn.Name.Name.L
if tableNameL != "" {
var matchedTable ast.ResultSetNode
for _, ts := range tableSources {
if tableNameL == ts.AsName.L {
// different table name.
matchedTable = ts
break
} else if ts.AsName.L != "" {
// Table as name shadows table real name.
continue
}
if tn, ok := ts.Source.(*ast.TableName); ok {
if cn.Name.Schema.L != "" && cn.Name.Schema.L != tn.Schema.L {
continue
}
if tableNameL == tn.Name.L {
matchedTable = ts
}
}
}
if matchedTable != nil {
resultFields := matchedTable.GetResultFields()
for _, rf := range resultFields {
if rf.ColumnAsName.L == columnNameL || rf.Column.Name.L == columnNameL {
// resolve column.
matchedResultField = rf
break
}
}
}
} else {
for _, ts := range tableSources {
rfs := ts.GetResultFields()
for _, rf := range rfs {
matchAsName := rf.ColumnAsName.L != "" && rf.ColumnAsName.L == columnNameL
matchColumnName := rf.ColumnAsName.L == "" && rf.Column.Name.L == columnNameL
if matchAsName || matchColumnName {
if matchedResultField != nil {
nr.Err = errors.Errorf("column %s is ambiguous.", cn.Name.Name.O)
return true
}
matchedResultField = rf
}
}
}
}
if matchedResultField != nil {
// Bind column.
cn.Refer = matchedResultField
return true
}
return false
}
func (nr *nameResolver) resolveColumnInResultFields(ctx *resolverContext, cn *ast.ColumnNameExpr, rfs []*ast.ResultField) bool {
var matched *ast.ResultField
for _, rf := range rfs {
if cn.Name.Table.L != "" {
// Check table name
if rf.TableAsName.L != "" {
if cn.Name.Table.L != rf.TableAsName.L {
continue
}
} else if cn.Name.Table.L != rf.Table.Name.L {
continue
}
}
matchAsName := cn.Name.Name.L == rf.ColumnAsName.L
var matchColumnName bool
if ctx.inHaving {
matchColumnName = cn.Name.Name.L == rf.Column.Name.L
} else {
matchColumnName = rf.ColumnAsName.L == "" && cn.Name.Name.L == rf.Column.Name.L
}
if matchAsName || matchColumnName {
if rf.Column.Name.L == "" {
// This is not a real table column, resolve it directly.
cn.Refer = rf
return true
}
if matched == nil {
matched = rf
} else {
sameColumn := matched.TableName == rf.TableName && matched.Column.Name.L == rf.Column.Name.L
if !sameColumn {
nr.Err = errors.Errorf("column %s is ambiguous.", cn.Name.Name.O)
return true
}
}
}
}
if matched != nil {
// If in GroupBy, we clone the ResultField
if ctx.inGroupBy || ctx.inHaving || ctx.inOrderBy {
nf := *matched
expr := matched.Expr
if cexpr, ok := expr.(*ast.ColumnNameExpr); ok {
expr = cexpr.Refer.Expr
}
nf.Expr = expr
matched = &nf
}
// Bind column.
cn.Refer = matched
return true
}
return false
}
// handleFieldList expands wild card field and sets fieldList in current context.
func (nr *nameResolver) handleFieldList(fieldList *ast.FieldList) {
var resultFields []*ast.ResultField
for _, v := range fieldList.Fields {
resultFields = append(resultFields, nr.createResultFields(v)...)
}
nr.currentContext().fieldList = resultFields
}
func getInnerFromParentheses(expr ast.ExprNode) ast.ExprNode {
if pexpr, ok := expr.(*ast.ParenthesesExpr); ok {
return getInnerFromParentheses(pexpr.Expr)
}
return expr
}
// createResultFields creates result field list for a single select field.
func (nr *nameResolver) createResultFields(field *ast.SelectField) (rfs []*ast.ResultField) {
ctx := nr.currentContext()
if field.WildCard != nil {
if len(ctx.tables) == 0 {
nr.Err = errors.New("No table used.")
return
}
tableRfs := []*ast.ResultField{}
if field.WildCard.Table.L == "" {
for _, v := range ctx.tables {
tableRfs = append(tableRfs, v.GetResultFields()...)
}
} else {
name := nr.tableUniqueName(field.WildCard.Schema, field.WildCard.Table)
tableIdx, ok1 := ctx.tableMap[name]
derivedTableIdx, ok2 := ctx.derivedTableMap[name]
if !ok1 && !ok2 {
nr.Err = errors.Errorf("unknown table %s.", field.WildCard.Table.O)
}
if ok1 {
tableRfs = ctx.tables[tableIdx].GetResultFields()
}
if ok2 {
tableRfs = append(tableRfs, ctx.tables[derivedTableIdx].GetResultFields()...)
}
}
for _, trf := range tableRfs {
// Convert it to ColumnNameExpr
cn := &ast.ColumnName{
Schema: trf.DBName,
Table: trf.Table.Name,
Name: trf.ColumnAsName,
}
cnExpr := &ast.ColumnNameExpr{
Name: cn,
Refer: trf,
}
ast.SetFlag(cnExpr)
cnExpr.SetType(trf.Expr.GetType())
rf := *trf
rf.Expr = cnExpr
rfs = append(rfs, &rf)
}
return
}
// The column is visited before so it must has been resolved already.
rf := &ast.ResultField{ColumnAsName: field.AsName}
innerExpr := getInnerFromParentheses(field.Expr)
switch v := innerExpr.(type) {
case *ast.ColumnNameExpr:
rf.Column = v.Refer.Column
rf.Table = v.Refer.Table
rf.DBName = v.Refer.DBName
rf.TableName = v.Refer.TableName
rf.Expr = v
default:
rf.Column = &model.ColumnInfo{} // Empty column info.
rf.Table = &model.TableInfo{} // Empty table info.
rf.Expr = v
}
if field.AsName.L == "" {
switch x := innerExpr.(type) {
case *ast.ColumnNameExpr:
rf.ColumnAsName = model.NewCIStr(x.Name.Name.O)
case *ast.ValueExpr:
if innerExpr.Text() != "" {
rf.ColumnAsName = model.NewCIStr(innerExpr.Text())
} else {
rf.ColumnAsName = model.NewCIStr(field.Text())
}
default:
rf.ColumnAsName = model.NewCIStr(field.Text())
}
}
rfs = append(rfs, rf)
return
}
func appendTableSources(in []*ast.TableSource, resultSetNode ast.ResultSetNode) (out []*ast.TableSource) {
switch v := resultSetNode.(type) {
case *ast.TableSource:
out = append(in, v)
case *ast.Join:
out = appendTableSources(in, v.Left)
if v.Right != nil {
out = appendTableSources(out, v.Right)
}
}
return
}
func (nr *nameResolver) tableUniqueName(schema, table model.CIStr) string {
if schema.L != "" && schema.L != nr.DefaultSchema.L {
return schema.L + "." + table.L
}
return table.L
}
func (nr *nameResolver) handlePosition(pos *ast.PositionExpr) {
ctx := nr.currentContext()
if pos.N < 1 || pos.N > len(ctx.fieldList) {
nr.Err = errors.Errorf("Unknown column '%d'", pos.N)
return
}
matched := ctx.fieldList[pos.N-1]
nf := *matched
expr := matched.Expr
if cexpr, ok := expr.(*ast.ColumnNameExpr); ok {
expr = cexpr.Refer.Expr
}
nf.Expr = expr
pos.Refer = &nf
if nr.currentContext().inGroupBy {
// make sure item is not aggregate function
if ast.HasAggFlag(pos.Refer.Expr) {
nr.Err = errors.New("group by cannot contain aggregate function")
}
}
}
func (nr *nameResolver) handleUnionSelectList(u *ast.UnionSelectList) {
firstSelFields := u.Selects[0].GetResultFields()
unionFields := make([]*ast.ResultField, len(firstSelFields))
// Copy first result fields, because we may change the result field type.
for i, v := range firstSelFields {
rf := *v
col := *v.Column
rf.Column = &col
if rf.Column.Flen == 0 {
rf.Column.Flen = types.UnspecifiedLength
}
rf.Expr = &ast.ValueExpr{}
unionFields[i] = &rf
}
nr.currentContext().fieldList = unionFields
}
func (nr *nameResolver) fillShowFields(s *ast.ShowStmt) {
if s.DBName == "" {
if s.Table != nil && s.Table.Schema.L != "" {
s.DBName = s.Table.Schema.O
} else {
s.DBName = nr.DefaultSchema.O
}
} else if s.Table != nil && s.Table.Schema.L == "" {
s.Table.Schema = model.NewCIStr(s.DBName)
}
var fields []*ast.ResultField
var (
names []string
ftypes []byte
)
switch s.Tp {
case ast.ShowEngines:
names = []string{"Engine", "Support", "Comment", "Transactions", "XA", "Savepoints"}
case ast.ShowDatabases:
names = []string{"Database"}
case ast.ShowTables:
names = []string{fmt.Sprintf("Tables_in_%s", s.DBName)}
if s.Full {
names = append(names, "Table_type")
}
case ast.ShowTableStatus:
names = []string{"Name", "Engine", "Version", "Row_format", "Rows", "Avg_row_length",
"Data_length", "Max_data_length", "Index_length", "Data_free", "Auto_increment",
"Create_time", "Update_time", "Check_time", "Collation", "Checksum",
"Create_options", "Comment"}
ftypes = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong, mysql.TypeVarchar, mysql.TypeLonglong, mysql.TypeLonglong,
mysql.TypeLonglong, mysql.TypeLonglong, mysql.TypeLonglong, mysql.TypeLonglong, mysql.TypeLonglong,
mysql.TypeDatetime, mysql.TypeDatetime, mysql.TypeDatetime, mysql.TypeVarchar, mysql.TypeVarchar,
mysql.TypeVarchar, mysql.TypeVarchar}
case ast.ShowColumns:
names = column.ColDescFieldNames(s.Full)
case ast.ShowWarnings:
names = []string{"Level", "Code", "Message"}
ftypes = []byte{mysql.TypeVarchar, mysql.TypeLong, mysql.TypeVarchar}
case ast.ShowCharset:
names = []string{"Charset", "Description", "Default collation", "Maxlen"}
ftypes = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong}
case ast.ShowVariables:
names = []string{"Variable_name", "Value"}
case ast.ShowStatus:
names = []string{"Variable_name", "Value"}
case ast.ShowCollation:
names = []string{"Collation", "Charset", "Id", "Default", "Compiled", "Sortlen"}
ftypes = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong,
mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong}
case ast.ShowCreateTable:
names = []string{"Table", "Create Table"}
case ast.ShowGrants:
names = []string{fmt.Sprintf("Grants for %s", s.User)}
case ast.ShowTriggers:
names = []string{"Trigger", "Event", "Table", "Statement", "Timing", "Created",
"sql_mode", "Definer", "character_set_client", "collation_connection", "Database Collation"}
ftypes = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar,
mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar}
case ast.ShowProcedureStatus:
names = []string{}
ftypes = []byte{}
case ast.ShowIndex:
names = []string{"Table", "Non_unique", "Key_name", "Seq_in_index",
"Column_name", "Collation", "Cardinality", "Sub_part", "Packed",
"Null", "Index_type", "Comment", "Index_comment"}
ftypes = []byte{mysql.TypeVarchar, mysql.TypeLonglong, mysql.TypeVarchar, mysql.TypeLonglong,
mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong, mysql.TypeLonglong,
mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeVarchar}
}
for i, name := range names {
f := &ast.ResultField{
ColumnAsName: model.NewCIStr(name),
Column: &model.ColumnInfo{}, // Empty column info.
Table: &model.TableInfo{}, // Empty table info.
}
if ftypes == nil || ftypes[i] == 0 {
// use varchar as the default return column type
f.Column.Tp = mysql.TypeVarchar
} else {
f.Column.Tp = ftypes[i]
}
f.Column.Charset, f.Column.Collate = types.DefaultCharsetForType(f.Column.Tp)
f.Expr = &ast.ValueExpr{}
f.Expr.SetType(&f.Column.FieldType)
fields = append(fields, f)
}
if s.Pattern != nil && s.Pattern.Expr == nil {
rf := fields[0]
s.Pattern.Expr = &ast.ColumnNameExpr{
Name: &ast.ColumnName{Name: rf.ColumnAsName},
}
ast.SetFlag(s.Pattern)
}
s.SetResultFields(fields)
nr.currentContext().fieldList = fields
}