// DropTable drops a table.
// Privileges: WRITE on table.
// Notes: postgres allows only the table owner to DROP a table.
// mysql requires the DROP privilege on the table.
func (p *planner) DropTable(n *parser.DropTable) (planNode, error) {
// TODO(XisiHuang): should do truncate and delete descriptor in
// the same txn
for i, tableQualifiedName := range n.Names {
if err := tableQualifiedName.NormalizeTableName(p.session.Database); err != nil {
return nil, err
}
dbDesc, err := p.getDatabaseDesc(tableQualifiedName.Database())
if err != nil {
return nil, err
}
tbKey := tableKey{dbDesc.ID, tableQualifiedName.Table()}
nameKey := tbKey.Key()
gr, err := p.txn.Get(nameKey)
if err != nil {
return nil, err
}
if !gr.Exists() {
if n.IfExists {
// Noop.
continue
}
// Key does not exist, but we want it to: error out.
return nil, fmt.Errorf("table %q does not exist", tbKey.Name())
}
tableDesc := structured.TableDescriptor{}
if err := p.txn.GetProto(gr.ValueBytes(), &tableDesc); err != nil {
return nil, err
}
if err := tableDesc.Validate(); err != nil {
return nil, err
}
if !tableDesc.HasPrivilege(p.user, parser.PrivilegeWrite) {
return nil, fmt.Errorf("user %s does not have %s privilege on table %s",
p.user, parser.PrivilegeWrite, tableDesc.Name)
}
if _, err = p.Truncate(&parser.Truncate{Tables: n.Names[i : i+1]}); err != nil {
return nil, err
}
// Delete table descriptor
descKey := gr.ValueBytes()
b := &client.Batch{}
b.Del(descKey)
b.Del(nameKey)
err = p.txn.Run(b)
if err != nil {
return nil, err
}
}
return &valuesNode{}, nil
}
// Select selects rows from a single table.
// Privileges: READ on table
// Notes: postgres requires SELECT. Also requires UPDATE on "FOR UPDATE".
// mysql requires SELECT.
func (p *planner) Select(n *parser.Select) (planNode, error) {
var desc *structured.TableDescriptor
var index *structured.IndexDescriptor
var visibleCols []structured.ColumnDescriptor
switch len(n.From) {
case 0:
// desc remains nil.
case 1:
var err error
desc, err = p.getAliasedTableDesc(n.From[0])
if err != nil {
return nil, err
}
if !desc.HasPrivilege(p.user, parser.PrivilegeRead) {
return nil, fmt.Errorf("user %s does not have %s privilege on table %s",
p.user, parser.PrivilegeRead, desc.Name)
}
// This is only kosher because we know that getAliasedDesc() succeeded.
qname := n.From[0].(*parser.AliasedTableExpr).Expr.(*parser.QualifiedName)
indexName := qname.Index()
if indexName != "" && !strings.EqualFold(desc.PrimaryIndex.Name, indexName) {
for i := range desc.Indexes {
if strings.EqualFold(desc.Indexes[i].Name, indexName) {
// Remove all but the matching index from the descriptor.
desc.Indexes = desc.Indexes[i : i+1]
index = &desc.Indexes[0]
break
}
}
if index == nil {
return nil, fmt.Errorf("index \"%s\" not found", indexName)
}
// If the table was not aliased, use the index name instead of the table
// name for fully-qualified columns in the expression.
if n.From[0].(*parser.AliasedTableExpr).As == "" {
desc.Alias = index.Name
}
// Strip out any columns from the table that are not present in the
// index.
indexColIDs := map[structured.ColumnID]struct{}{}
for _, colID := range index.ColumnIDs {
indexColIDs[colID] = struct{}{}
}
for _, col := range desc.Columns {
if _, ok := indexColIDs[col.ID]; !ok {
continue
}
visibleCols = append(visibleCols, col)
}
} else {
index = &desc.PrimaryIndex
visibleCols = desc.Columns
}
default:
return nil, util.Errorf("TODO(pmattis): unsupported FROM: %s", n.From)
}
// Loop over the select expressions and expand them into the expressions
// we're going to use to generate the returned column set and the names for
// those columns.
exprs := make([]parser.Expr, 0, len(n.Exprs))
columns := make([]string, 0, len(n.Exprs))
for _, e := range n.Exprs {
// If a QualifiedName has a StarIndirection suffix we need to match the
// prefix of the qualified name to one of the tables in the query and
// then expand the "*" into a list of columns.
if qname, ok := e.Expr.(*parser.QualifiedName); ok {
if err := qname.NormalizeColumnName(); err != nil {
return nil, err
}
if qname.IsStar() {
if desc == nil {
return nil, fmt.Errorf("\"%s\" with no tables specified is not valid", qname)
}
if e.As != "" {
return nil, fmt.Errorf("\"%s\" cannot be aliased", qname)
}
tableName := qname.Table()
if tableName != "" && !strings.EqualFold(desc.Alias, tableName) {
return nil, fmt.Errorf("table \"%s\" not found", tableName)
}
if index != &desc.PrimaryIndex {
for _, col := range index.ColumnNames {
columns = append(columns, col)
exprs = append(exprs, &parser.QualifiedName{Base: parser.Name(col)})
}
} else {
for _, col := range desc.Columns {
columns = append(columns, col.Name)
exprs = append(exprs, &parser.QualifiedName{Base: parser.Name(col.Name)})
}
}
continue
}
}
exprs = append(exprs, e.Expr)
if e.As != "" {
columns = append(columns, string(e.As))
continue
}
// If the expression is a qualified name, use the column name, not the
// full qualification as the column name to return.
switch t := e.Expr.(type) {
case *parser.QualifiedName:
if err := t.NormalizeColumnName(); err != nil {
return nil, err
}
columns = append(columns, t.Column())
default:
columns = append(columns, e.Expr.String())
}
}
s := &scanNode{
txn: p.txn,
desc: desc,
index: index,
visibleCols: visibleCols,
columns: columns,
render: exprs,
}
if index != nil {
s.isSecondaryIndex = index != &desc.PrimaryIndex
}
if n.Where != nil {
s.filter = n.Where.Expr
}
return s, nil
}
// Select selects rows from a single table.
// Privileges: READ on table
// Notes: postgres requires SELECT. Also requires UPDATE on "FOR UPDATE".
// mysql requires SELECT.
func (p *planner) Select(n *parser.Select) (planNode, error) {
var desc *structured.TableDescriptor
switch len(n.From) {
case 0:
// desc remains nil.
case 1:
var err error
desc, err = p.getAliasedTableDesc(n.From[0])
if err != nil {
return nil, err
}
if !desc.HasPrivilege(p.user, parser.PrivilegeRead) {
return nil, fmt.Errorf("user %s does not have %s privilege on table %s",
p.user, parser.PrivilegeRead, desc.Name)
}
default:
return nil, util.Errorf("TODO(pmattis): unsupported FROM: %s", n.From)
}
// Loop over the select expressions and expand them into the expressions
// we're going to use to generate the returned column set and the names for
// those columns.
exprs := make([]parser.Expr, 0, len(n.Exprs))
columns := make([]string, 0, len(n.Exprs))
for _, e := range n.Exprs {
switch t := e.(type) {
case *parser.StarExpr:
if desc == nil {
return nil, fmt.Errorf("* with no tables specified is not valid")
}
for _, col := range desc.Columns {
columns = append(columns, col.Name)
exprs = append(exprs, &parser.QualifiedName{Base: parser.Name(col.Name)})
}
case *parser.NonStarExpr:
exprs = append(exprs, t.Expr)
if t.As != "" {
columns = append(columns, string(t.As))
} else {
// TODO(pmattis): Should verify at this point that any referenced
// columns are represented in the tables being selected from.
columns = append(columns, t.Expr.String())
}
}
}
s := &scanNode{
db: p.db,
desc: desc,
columns: columns,
render: exprs,
}
if n.Where != nil {
s.filter = n.Where.Expr
}
return s, nil
}
