// processAliasedTable produces a builder subtree for the given AliasedTableExpr.
// If the expression is a subquery, then the the route built for it will contain
// the entire subquery tree in the from clause, as if it was a table.
// The symtab entry for the query will be a tabsym where the columns
// will be built from the select expressions of the subquery.
// Since the table aliases only contain vindex columns, we'll follow
// the same rule: only columns from the subquery that are identified as
// vindex columns will be added to the tabsym.
// A symtab symbol can only point to a route. This means that we canoot
// support complex joins in subqueries yet.
func processAliasedTable(tableExpr *sqlparser.AliasedTableExpr, vschema VSchema) (builder, error) {
switch expr := tableExpr.Expr.(type) {
case *sqlparser.TableName:
eroute, table, err := getTablePlan(expr, vschema)
if err != nil {
return nil, err
}
alias := sqlparser.SQLName(sqlparser.String(expr))
astName := expr.Name
if tableExpr.As != "" {
alias = tableExpr.As
astName = alias
}
return newRoute(
sqlparser.TableExprs([]sqlparser.TableExpr{tableExpr}),
eroute,
table,
vschema,
alias,
astName,
), nil
case *sqlparser.Subquery:
sel, ok := expr.Select.(*sqlparser.Select)
if !ok {
return nil, errors.New("unsupported: union operator in subqueries")
}
subplan, err := processSelect(sel, vschema, nil)
if err != nil {
return nil, err
}
subroute, ok := subplan.(*route)
if !ok {
return nil, errors.New("unsupported: complex join in subqueries")
}
table := &vindexes.Table{
Keyspace: subroute.ERoute.Keyspace,
}
for _, colsyms := range subroute.Colsyms {
if colsyms.Vindex == nil {
continue
}
table.ColVindexes = append(table.ColVindexes, &vindexes.ColVindex{
Col: string(colsyms.Alias),
Vindex: colsyms.Vindex,
})
}
rtb := newRoute(
sqlparser.TableExprs([]sqlparser.TableExpr{tableExpr}),
subroute.ERoute,
table,
vschema,
tableExpr.As,
tableExpr.As,
)
subroute.Redirect = rtb
return rtb, nil
}
panic("unreachable")
}
// processAliasedTable produces a builder subtree for the given AliasedTableExpr.
// If the expression is a subquery, then the the route built for it will contain
// the entire subquery tree in the from clause, as if it was a table.
// The symtab entry for the query will be a tabsym where the columns
// will be built from the select expressions of the subquery.
// Since the table aliases only contain vindex columns, we'll follow
// the same rule: only columns from the subquery that are identified as
// vindex columns will be added to the tabsym.
// A symtab symbol can only point to a route. This means that we canoot
// support complex joins in subqueries yet.
func processAliasedTable(tableExpr *sqlparser.AliasedTableExpr, vschema VSchema) (builder, error) {
switch expr := tableExpr.Expr.(type) {
case *sqlparser.TableName:
eroute, table, err := getTablePlan(expr, vschema)
if err != nil {
return nil, err
}
alias := sqlparser.TableIdent(sqlparser.String(expr))
astName := expr.Name
if tableExpr.As != "" {
alias = tableExpr.As
astName = alias
}
return newRoute(
sqlparser.TableExprs([]sqlparser.TableExpr{tableExpr}),
eroute,
table,
vschema,
alias,
astName,
), nil
case *sqlparser.Subquery:
sel, ok := expr.Select.(*sqlparser.Select)
if !ok {
return nil, errors.New("unsupported: union operator in subqueries")
}
subplan, err := processSelect(sel, vschema, nil)
if err != nil {
return nil, err
}
subroute, ok := subplan.(*route)
if !ok {
return nil, errors.New("unsupported: complex join in subqueries")
}
table := &vindexes.Table{
Keyspace: subroute.ERoute.Keyspace,
}
for _, colsyms := range subroute.Colsyms {
if colsyms.Vindex == nil {
continue
}
// Check if a colvindex of the same name already exists.
// Dups are not allowed in subqueries in this situation.
for _, colVindex := range table.ColumnVindexes {
if colVindex.Column.Equal(cistring.CIString(colsyms.Alias)) {
return nil, fmt.Errorf("duplicate column aliases: %v", colsyms.Alias)
}
}
table.ColumnVindexes = append(table.ColumnVindexes, &vindexes.ColumnVindex{
Column: cistring.CIString(colsyms.Alias),
Vindex: colsyms.Vindex,
})
}
rtb := newRoute(
sqlparser.TableExprs([]sqlparser.TableExpr{tableExpr}),
subroute.ERoute,
table,
vschema,
tableExpr.As,
tableExpr.As,
)
subroute.Redirect = rtb
return rtb, nil
}
panic("unreachable")
}