// getTableID retrieves the table ID for the specified table. It uses the
// descriptor cache to perform lookups, falling back to the KV store when
// necessary.
func (p *planner) getTableID(qname *parser.QualifiedName) (sqlbase.ID, error) {
if err := qname.NormalizeTableName(p.session.Database); err != nil {
return 0, err
}
dbID, err := p.getDatabaseID(qname.Database())
if err != nil {
return 0, err
}
// Lookup the ID of the table in the cache. The use of the cache might cause
// the usage of a recently renamed table, but that's a race that could occur
// anyways.
// TODO(andrei): remove the used of p.systemConfig as a cache for table names,
// replace it with using the leases for resolving names, and do away with any
// races due to renames. We'll probably have to rewrite renames to perform
// an async schema change.
nameKey := tableKey{dbID, qname.Table()}
key := nameKey.Key()
if nameVal := p.systemConfig.GetValue(key); nameVal != nil {
id, err := nameVal.GetInt()
return sqlbase.ID(id), err
}
gr, err := p.txn.Get(key)
if err != nil {
return 0, err
}
if !gr.Exists() {
return 0, tableDoesNotExistError(qname.String())
}
return sqlbase.ID(gr.ValueInt()), nil
}
// getTableLease implements the SchemaAccessor interface.
func (p *planner) getTableLease(qname *parser.QualifiedName) (*sqlbase.TableDescriptor, error) {
if log.V(2) {
log.Infof("planner acquiring lease on table %q", qname)
}
if err := qname.NormalizeTableName(p.session.Database); err != nil {
return nil, err
}
if qname.Database() == sqlbase.SystemDB.Name || 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.
return p.mustGetTableDesc(qname)
}
dbID, err := p.getDatabaseID(qname.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.NormalizeName(l.Name) == sqlbase.NormalizeName(qname.Table()) &&
l.ParentID == dbID {
lease = l
if log.V(2) {
log.Infof("found lease in planner cache for table %q", qname)
}
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, qname.Table())
if err != nil {
if err == errDescriptorNotFound {
// Transform the descriptor error into an error that references the
// table's name.
return nil, sqlbase.NewUndefinedTableError(qname.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
}
// mustGetTableDesc implements the SchemaAccessor interface.
func (p *planner) mustGetTableDesc(qname *parser.QualifiedName) (*sqlbase.TableDescriptor, error) {
desc, err := p.getTableDesc(qname)
if err != nil {
return nil, err
}
if desc == nil {
return nil, sqlbase.NewUndefinedTableError(qname.String())
}
return desc, nil
}
// Initializes a scanNode with a tableName. Returns the table or index name that can be used for
// fully-qualified columns if an alias is not specified.
func (n *scanNode) initTable(
p *planner,
tableName *parser.QualifiedName,
indexHints *parser.IndexHints,
scanVisibility scanVisibility,
) (string, error) {
var err error
// AS OF SYSTEM TIME queries need to fetch the table descriptor at the
// specified time, and never lease anything. The proto transaction already
// has its timestamps set correctly so getTableDesc will fetch with the
// correct timestamp.
if p.asOf {
desc, err := p.getTableDesc(tableName)
if err != nil {
return "", err
}
if desc == nil {
return "", sqlbase.NewUndefinedTableError(tableName.String())
}
n.desc = *desc
} else {
n.desc, err = p.getTableLease(tableName)
}
if err != nil {
return "", err
}
if err := p.checkPrivilege(&n.desc, privilege.SELECT); err != nil {
return "", err
}
alias := n.desc.Name
if indexHints != nil && indexHints.Index != "" {
indexName := sqlbase.NormalizeName(string(indexHints.Index))
if indexName == sqlbase.NormalizeName(n.desc.PrimaryIndex.Name) {
n.specifiedIndex = &n.desc.PrimaryIndex
} else {
for i := range n.desc.Indexes {
if indexName == sqlbase.NormalizeName(n.desc.Indexes[i].Name) {
n.specifiedIndex = &n.desc.Indexes[i]
break
}
}
if n.specifiedIndex == nil {
return "", fmt.Errorf("index \"%s\" not found", indexName)
}
}
}
n.noIndexJoin = (indexHints != nil && indexHints.NoIndexJoin)
n.initDescDefaults(scanVisibility)
return alias, nil
}
// getTableLease acquires a lease for the specified table. The lease will be
// released when the planner closes. Note that a shallow copy of the table
// descriptor is returned. It is safe to mutate fields of the returned
// descriptor, but the values those fields point to should not be modified.
func (p *planner) getTableLease(qname *parser.QualifiedName) (sqlbase.TableDescriptor, error) {
if err := qname.NormalizeTableName(p.session.Database); err != nil {
return sqlbase.TableDescriptor{}, err
}
if qname.Database() == sqlbase.SystemDB.Name || 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.
desc, err := p.getTableDesc(qname)
if err != nil {
return sqlbase.TableDescriptor{}, err
}
if desc == nil {
return sqlbase.TableDescriptor{}, tableDoesNotExistError(qname.String())
}
return *desc, nil
}
tableID, err := p.getTableID(qname)
if err != nil {
return sqlbase.TableDescriptor{}, err
}
var lease *LeaseState
var commitBy time.Time
for _, l := range p.leases {
commitBy = updateCommitBy(commitBy, l)
if l.TableDescriptor.ID == tableID {
lease = l
}
}
if lease == nil {
var err error
lease, err = p.leaseMgr.Acquire(p.txn, tableID, 0)
if err != nil {
if _, ok := err.(*roachpb.DescriptorNotFoundError); ok {
// Transform the descriptor error into an error that references the
// table's name.
return sqlbase.TableDescriptor{}, tableDoesNotExistError(qname.String())
}
return sqlbase.TableDescriptor{}, err
}
p.leases = append(p.leases, lease)
commitBy = updateCommitBy(commitBy, lease)
}
p.txn.SetDeadline(roachpb.Timestamp{WallTime: commitBy.UnixNano()})
return lease.TableDescriptor, nil
}
// getTableID retrieves the table ID for the specified table.
func getTableID(p *planner, qname *parser.QualifiedName) (sqlbase.ID, error) {
if err := qname.NormalizeTableName(p.session.Database); err != nil {
return 0, err
}
dbID, err := p.getDatabaseID(qname.Database())
if err != nil {
return 0, err
}
nameKey := tableKey{dbID, qname.Table()}
key := nameKey.Key()
gr, err := p.txn.Get(key)
if err != nil {
return 0, err
}
if !gr.Exists() {
return 0, sqlbase.NewUndefinedTableError(qname.String())
}
return sqlbase.ID(gr.ValueInt()), nil
}
