// getVirtualTableEntry checks if the provided name matches a virtual database/table
// pair. The function will return the table's virtual table entry if the name matches
// a specific table. It will return an error if the name references a virtual database
// but the table is non-existent.
func getVirtualTableEntry(tn *parser.TableName) (virtualTableEntry, error) {
if db, ok := getVirtualSchemaEntry(tn.Database()); ok {
if t, ok := db.tables[sqlbase.NormalizeName(tn.TableName)]; ok {
return t, nil
}
return virtualTableEntry{}, sqlbase.NewUndefinedTableError(tn.String())
}
return virtualTableEntry{}, nil
}
// mustGetTableDesc implements the SchemaAccessor interface.
func (p *planner) mustGetTableDesc(tn *parser.TableName) (*sqlbase.TableDescriptor, error) {
desc, err := p.getTableDesc(tn)
if err != nil {
return nil, err
}
if desc == nil {
return nil, sqlbase.NewUndefinedTableError(tn.String())
}
if err := filterTableState(desc); err != nil {
return nil, err
}
return desc, nil
}
// expandStar returns the array of column metadata and name
// expressions that correspond to the expansion of a star.
func (src *dataSourceInfo) expandStar(
v parser.VarName, qvals qvalMap,
) (columns []ResultColumn, exprs []parser.TypedExpr, err error) {
if len(src.sourceColumns) == 0 {
return nil, nil, fmt.Errorf("cannot use \"%s\" without a FROM clause", v)
}
colSel := func(idx int) {
col := src.sourceColumns[idx]
if !col.hidden {
qval := qvals.getQVal(columnRef{src, idx})
columns = append(columns, ResultColumn{Name: col.Name, Typ: qval.datum})
exprs = append(exprs, qval)
}
}
tableName := parser.TableName{}
if a, ok := v.(*parser.AllColumnsSelector); ok {
tableName = a.TableName
}
if tableName.Table() == "" {
for i := 0; i < len(src.sourceColumns); i++ {
colSel(i)
}
} else {
norm := sqlbase.NormalizeTableName(tableName)
qualifiedTn, err := src.checkDatabaseName(norm)
if err != nil {
return nil, nil, err
}
colRange, ok := src.sourceAliases[qualifiedTn]
if !ok {
return nil, nil, fmt.Errorf("table %q not found", tableName.String())
}
for _, i := range colRange {
colSel(i)
}
}
return columns, exprs, nil
}
// getDataSource builds a planDataSource from a single data source clause
// (TableExpr) in a SelectClause.
func (p *planner) getDataSource(
src parser.TableExpr,
hints *parser.IndexHints,
scanVisibility scanVisibility,
) (planDataSource, error) {
switch t := src.(type) {
case *parser.NormalizableTableName:
// Usual case: a table.
tn, err := t.NormalizeWithDatabaseName(p.session.Database)
if err != nil {
return planDataSource{}, err
}
// Is this perhaps a name for a virtual table?
ds, foundVirtual, err := p.getVirtualDataSource(tn)
if err != nil {
return planDataSource{}, err
}
if foundVirtual {
return ds, nil
}
// This name designates a real table.
scan := p.Scan()
if err := scan.initTable(p, tn, hints, scanVisibility); err != nil {
return planDataSource{}, err
}
return planDataSource{
info: newSourceInfoForSingleTable(*tn, scan.Columns()),
plan: scan,
}, nil
case *parser.Subquery:
// We have a subquery (this includes a simple "VALUES").
plan, err := p.newPlan(t.Select, nil, false)
if err != nil {
return planDataSource{}, err
}
return planDataSource{
info: newSourceInfoForSingleTable(parser.TableName{}, plan.Columns()),
plan: plan,
}, nil
case *parser.JoinTableExpr:
// Joins: two sources.
left, err := p.getDataSource(t.Left, nil, scanVisibility)
if err != nil {
return left, err
}
right, err := p.getDataSource(t.Right, nil, scanVisibility)
if err != nil {
return right, err
}
return p.makeJoin(t.Join, left, right, t.Cond)
case *parser.ParenTableExpr:
return p.getDataSource(t.Expr, hints, scanVisibility)
case *parser.AliasedTableExpr:
// Alias clause: source AS alias(cols...)
src, err := p.getDataSource(t.Expr, t.Hints, scanVisibility)
if err != nil {
return src, err
}
var tableAlias parser.TableName
if t.As.Alias != "" {
// If an alias was specified, use that.
tableAlias.TableName = parser.Name(sqlbase.NormalizeName(t.As.Alias))
src.info.sourceAliases = sourceAliases{
tableAlias: fillColumnRange(0, len(src.info.sourceColumns)-1),
}
}
colAlias := t.As.Cols
if len(colAlias) > 0 {
// Make a copy of the slice since we are about to modify the contents.
src.info.sourceColumns = append([]ResultColumn(nil), src.info.sourceColumns...)
// The column aliases can only refer to explicit columns.
for colIdx, aliasIdx := 0, 0; aliasIdx < len(colAlias); colIdx++ {
if colIdx >= len(src.info.sourceColumns) {
var srcName string
if tableAlias.DatabaseName != "" {
srcName = tableAlias.String()
} else {
srcName = tableAlias.TableName.String()
}
return planDataSource{}, errors.Errorf(
"source %q has %d columns available but %d columns specified",
srcName, aliasIdx, len(colAlias))
}
if src.info.sourceColumns[colIdx].hidden {
continue
}
src.info.sourceColumns[colIdx].Name = string(colAlias[aliasIdx])
aliasIdx++
}
}
return src, nil
default:
return planDataSource{}, errors.Errorf("unsupported FROM type %T", src)
}
}
// getTableLease implements the SchemaAccessor interface.
func (p *planner) getTableLease(tn *parser.TableName) (*sqlbase.TableDescriptor, error) {
if log.V(2) {
log.Infof(p.ctx(), "planner acquiring lease on table %s", tn)
}
isSystemDB := tn.Database() == sqlbase.SystemDB.Name
isVirtualDB := isVirtualDatabase(tn.Database())
if isSystemDB || isVirtualDB || testDisableTableLeases {
// We don't go through the normal lease mechanism for:
// - system tables. The system.lease and system.descriptor table, in
// particular, are problematic because they are used for acquiring
// leases itself, creating a chicken&egg problem.
// - virtual tables. These tables' descriptors are not persisted,
// so they cannot be leased. Instead, we simply return the static
// descriptor and rely on the immutability privileges set on the
// descriptors to cause upper layers to reject mutations statements.
tbl, err := p.mustGetTableDesc(tn)
if err != nil {
return nil, err
}
if err := filterTableState(tbl); err != nil {
return nil, err
}
return tbl, nil
}
dbID, err := p.getDatabaseID(tn.Database())
if err != nil {
return nil, err
}
// First, look to see if we already have a lease for this table.
// This ensures that, once a SQL transaction resolved name N to id X, it will
// continue to use N to refer to X even if N is renamed during the
// transaction.
var lease *LeaseState
for _, l := range p.leases {
if sqlbase.ReNormalizeName(l.Name) == sqlbase.NormalizeName(tn.TableName) &&
l.ParentID == dbID {
lease = l
if log.V(2) {
log.Infof(p.ctx(), "found lease in planner cache for table %q", tn)
}
break
}
}
// If we didn't find a lease or the lease is about to expire, acquire one.
if lease == nil || p.removeLeaseIfExpiring(lease) {
var err error
lease, err = p.leaseMgr.AcquireByName(p.txn, dbID, tn.Table())
if err != nil {
if err == sqlbase.ErrDescriptorNotFound {
// Transform the descriptor error into an error that references the
// table's name.
return nil, sqlbase.NewUndefinedTableError(tn.String())
}
return nil, err
}
p.leases = append(p.leases, lease)
// If the lease we just acquired expires before the txn's deadline, reduce
// the deadline.
p.txn.UpdateDeadlineMaybe(hlc.Timestamp{WallTime: lease.Expiration().UnixNano()})
}
return &lease.TableDescriptor, nil
}
