func (sei *session) buildSelectPlan(stmt *sqlparser.Select) (*Plan, error) {
plan := &Plan{}
var err error
var tableName string
switch v := (stmt.From[0]).(type) {
case *sqlparser.AliasedTableExpr:
tableName = sqlparser.String(v.Expr)
case *sqlparser.JoinTableExpr:
if ate, ok := (v.LeftExpr).(*sqlparser.AliasedTableExpr); ok {
tableName = sqlparser.String(ate.Expr)
} else {
tableName = sqlparser.String(v)
}
default:
tableName = sqlparser.String(v)
}
// get tableName
t, err := sei.getMeta().GetTable(sei.user, sei.db, tableName)
if err != nil {
return nil, err
}
plan.Table = t
// rewrite limit
err = plan.rewriteLimit(stmt)
if err != nil {
return nil, err
}
// generate sql
err = plan.generateSQL(stmt)
return plan, err
}
// limit
func (p *Plan) rewriteLimit(stmt *sqlparser.Select) (err error) {
origin := stmt.Limit
// get offset and count
if origin == nil {
return
}
var offset, count int64
if origin.Offset == nil {
offset = 0
} else {
o, ok := origin.Offset.(sqlparser.NumVal)
if !ok {
err = fmt.Errorf("invalid select limit %s", sqlparser.String(stmt.Limit))
return
}
if offset, err = strconv.ParseInt(string([]byte(o)), 10, 64); err != nil {
return
}
}
o, ok := origin.Rowcount.(sqlparser.NumVal)
if !ok {
err = fmt.Errorf("invalid limit %s", sqlparser.String(stmt.Limit))
return
}
if count, err = strconv.ParseInt(string([]byte(o)), 10, 64); err != nil {
return
}
if count < 0 {
err = fmt.Errorf("invalid limit %s", sqlparser.String(stmt.Limit))
return
}
// rewrite limit stmt
stmt.Limit.Offset = sqlparser.NumVal([]byte("0"))
stmt.Limit.Rowcount = sqlparser.NumVal([]byte(strconv.FormatInt(count+offset, 10)))
p.offset = offset
p.count = count
return
}
func (sei *session) sortResultSet(set *mysql.Resultset, stmt *sqlparser.Select) error {
if len(stmt.OrderBy) > 0 {
glog.Info("Sort select results")
ks := make([]mysql.SortKey, 0, len(stmt.OrderBy))
for _, o := range stmt.OrderBy {
ks = append(ks, mysql.SortKey{
Direction: o.Direction,
Name: sqlparser.String(o.Expr),
})
}
return set.Sort(ks)
}
return nil
}
func (sei *session) buildUpdatePlan(stmt *sqlparser.Update) (*Plan, error) {
plan := &Plan{}
var err error
var tableName = sqlparser.String(stmt.Table)
// get tableName
t, err := sei.getMeta().GetTable(sei.user, sei.db, tableName)
if err != nil {
return nil, err
}
plan.Table = t
// generate sql
err = plan.generateSQL(stmt)
return plan, err
}