forked from cockroachdb/cockroach
/
table.go
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/
table.go
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// Copyright 2015 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
//
// Author: Peter Mattis (peter@cockroachlabs.com)
// Author: Andrei Matei (andreimatei1@gmail.com)
package sql
import (
"bytes"
"fmt"
"github.com/cockroachdb/cockroach/internal/client"
"github.com/cockroachdb/cockroach/roachpb"
"github.com/cockroachdb/cockroach/sql/parser"
"github.com/cockroachdb/cockroach/sql/sqlbase"
"github.com/cockroachdb/cockroach/util/encoding"
"github.com/cockroachdb/cockroach/util/hlc"
"github.com/cockroachdb/cockroach/util/log"
"github.com/pkg/errors"
)
var testDisableTableLeases bool
// TestDisableTableLeases disables table leases and returns
// a function that can be used to enable it.
func TestDisableTableLeases() func() {
testDisableTableLeases = true
return func() {
testDisableTableLeases = false
}
}
// tableKey implements sqlbase.DescriptorKey.
type tableKey struct {
parentID sqlbase.ID
name string
}
func (tk tableKey) Key() roachpb.Key {
return sqlbase.MakeNameMetadataKey(tk.parentID, tk.name)
}
func (tk tableKey) Name() string {
return tk.name
}
var errDescriptorNotFound = errors.New("descriptor not found")
// getTableDescFromID retrieves the table descriptor for the table
// ID passed in using an existing txn. Teturns an error if the
// descriptor doesn't exist or if it exists and is not a table.
func getTableDescFromID(txn *client.Txn, id sqlbase.ID) (*sqlbase.TableDescriptor, error) {
desc := &sqlbase.Descriptor{}
descKey := sqlbase.MakeDescMetadataKey(id)
if err := txn.GetProto(descKey, desc); err != nil {
return nil, err
}
table := desc.GetTable()
if table == nil {
return nil, errDescriptorNotFound
}
return table, nil
}
// getKeysForTableDescriptor retrieves the KV keys corresponding
// to the zone, name and descriptor of a table.
func getKeysForTableDescriptor(
tableDesc *sqlbase.TableDescriptor,
) (zoneKey roachpb.Key, nameKey roachpb.Key, descKey roachpb.Key) {
zoneKey = sqlbase.MakeZoneKey(tableDesc.ID)
nameKey = sqlbase.MakeNameMetadataKey(tableDesc.ParentID, tableDesc.GetName())
descKey = sqlbase.MakeDescMetadataKey(tableDesc.ID)
return
}
// SchemaAccessor provides helper methods for using the SQL schema.
type SchemaAccessor interface {
// getTableNames retrieves the list of qualified names of tables
// present in the given database.
getTableNames(dbDesc *sqlbase.DatabaseDescriptor) (parser.QualifiedNames, error)
// expandTableGlob expands wildcards from the end of `expr` and
// returns the list of matching tables.
// `expr` is possibly modified to be qualified with the database it refers to.
// `expr` is assumed to be of one of several forms:
// database.table
// table
// *
expandTableGlob(expr *parser.QualifiedName) (parser.QualifiedNames, error)
// getTableDesc returns a table descriptor, or nil if the descriptor
// is not found. If you want to transform the not found condition
// into an error, use newUndefinedTableError().
getTableDesc(qname *parser.QualifiedName) (*sqlbase.TableDescriptor, error)
// NB: one can use getTableDescFromID() to retrieve a descriptor for
// a table from a transaction using its ID, assuming it was loaded
// in the transaction already.
// notifySchemaChange notifies that an outstanding schema change
// exists for the table.
notifySchemaChange(id sqlbase.ID, mutationID sqlbase.MutationID)
// 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.
getTableLease(qname *parser.QualifiedName) (sqlbase.TableDescriptor, error)
// getAliasedTableLease looks up the table descriptor for an alias table
// expression.
getAliasedTableLease(n parser.TableExpr) (*sqlbase.TableDescriptor, error)
// releaseLeases releases all leases currently held by the planner.
releaseLeases()
// writeTableDesc effectively writes a table descriptor to the
// database within the current planner transaction.
writeTableDesc(tableDesc *sqlbase.TableDescriptor) error
}
var _ SchemaAccessor = &planner{}
// getTableDesc implements the SchemaAccessor interface.
func (p *planner) getTableDesc(qname *parser.QualifiedName) (*sqlbase.TableDescriptor, error) {
if err := qname.NormalizeTableName(p.session.Database); err != nil {
return nil, err
}
dbDesc, err := p.getDatabaseDesc(qname.Database())
if err != nil {
return nil, err
}
if dbDesc == nil {
return nil, sqlbase.NewUndefinedDatabaseError(qname.Database())
}
desc := sqlbase.TableDescriptor{}
found, err := p.getDescriptor(tableKey{parentID: dbDesc.ID, name: qname.Table()}, &desc)
if err != nil {
return nil, err
}
if !found {
return nil, nil
}
return &desc, 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 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{}, sqlbase.NewUndefinedTableError(qname.String())
}
return *desc, nil
}
dbID, err := p.getDatabaseID(qname.Database())
if err != nil {
return sqlbase.TableDescriptor{}, 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 sqlbase.TableDescriptor{}, sqlbase.NewUndefinedTableError(qname.String())
}
return sqlbase.TableDescriptor{}, 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
}
// getTableLeaseByID is a by-ID variant of getTableLease (i.e. uses same cache).
func (p *planner) getTableLeaseByID(tableID sqlbase.ID) (*sqlbase.TableDescriptor, error) {
if log.V(2) {
log.Infof("planner acquiring lease on table ID %d", tableID)
}
// First, look to see if we already have a lease for this table -- including
// leases acquired via `getTableLease`.
var lease *LeaseState
for _, l := range p.leases {
if l.ID == tableID {
lease = l
if log.V(2) {
log.Infof("found lease in planner cache for table %d", tableID)
}
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.Acquire(p.txn, tableID, 0)
if err != nil {
if err == errDescriptorNotFound {
// Transform the descriptor error into an error that references the
// table's ID.
return nil, sqlbase.NewUndefinedTableError(fmt.Sprintf("<id=%d>", tableID))
}
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
}
// removeLeaseIfExpiring removes a lease and returns true if it is about to expire.
// The method also resets the transaction deadline.
func (p *planner) removeLeaseIfExpiring(lease *LeaseState) bool {
if lease == nil || lease.hasSomeLifeLeft(p.leaseMgr.clock) {
return false
}
// Remove the lease from p.leases.
idx := -1
for i, l := range p.leases {
if l == lease {
idx = i
break
}
}
if idx == -1 {
log.Warningf("lease (%s) not found", lease)
return false
}
p.leases[idx] = p.leases[len(p.leases)-1]
p.leases[len(p.leases)-1] = nil
p.leases = p.leases[:len(p.leases)-1]
if err := p.leaseMgr.Release(lease); err != nil {
log.Warning(err)
}
// Reset the deadline so that a new deadline will be set after the lease is acquired.
p.txn.ResetDeadline()
for _, l := range p.leases {
p.txn.UpdateDeadlineMaybe(hlc.Timestamp{WallTime: l.Expiration().UnixNano()})
}
return true
}
// getTableNames implements the SchemaAccessor interface.
func (p *planner) getTableNames(dbDesc *sqlbase.DatabaseDescriptor) (parser.QualifiedNames, error) {
prefix := sqlbase.MakeNameMetadataKey(dbDesc.ID, "")
sr, err := p.txn.Scan(prefix, prefix.PrefixEnd(), 0)
if err != nil {
return nil, err
}
var qualifiedNames parser.QualifiedNames
for _, row := range sr {
_, tableName, err := encoding.DecodeUnsafeStringAscending(
bytes.TrimPrefix(row.Key, prefix), nil)
if err != nil {
return nil, err
}
qname := &parser.QualifiedName{
Base: parser.Name(dbDesc.Name),
Indirect: parser.Indirection{parser.NameIndirection(tableName)},
}
if err := qname.NormalizeTableName(""); err != nil {
return nil, err
}
qualifiedNames = append(qualifiedNames, qname)
}
return qualifiedNames, nil
}
// getAliasedTableLease implements the SchemaAccessor interface.
func (p *planner) getAliasedTableLease(n parser.TableExpr) (*sqlbase.TableDescriptor, error) {
ate, ok := n.(*parser.AliasedTableExpr)
if !ok {
return nil, errors.Errorf("TODO(pmattis): unsupported FROM: %s", n)
}
table, ok := ate.Expr.(*parser.QualifiedName)
if !ok {
return nil, errors.Errorf("TODO(pmattis): unsupported FROM: %s", n)
}
desc, err := p.getTableLease(table)
if err != nil {
return nil, err
}
return &desc, nil
}
// notifySchemaChange implements the SchemaAccessor interface.
func (p *planner) notifySchemaChange(id sqlbase.ID, mutationID sqlbase.MutationID) {
sc := SchemaChanger{
tableID: id,
mutationID: mutationID,
nodeID: p.evalCtx.NodeID,
leaseMgr: p.leaseMgr,
}
p.session.TxnState.schemaChangers.queueSchemaChanger(sc)
}
// releaseLeases implements the SchemaAccessor interface.
func (p *planner) releaseLeases() {
if p.leases != nil {
for _, lease := range p.leases {
if err := p.leaseMgr.Release(lease); err != nil {
log.Warning(err)
}
}
p.leases = nil
}
}
// writeTableDesc implements the SchemaAccessor interface.
func (p *planner) writeTableDesc(tableDesc *sqlbase.TableDescriptor) error {
return p.txn.Put(sqlbase.MakeDescMetadataKey(tableDesc.GetID()),
sqlbase.WrapDescriptor(tableDesc))
}
// expandTableGlob implements the SchemaAccessor interface.
func (p *planner) expandTableGlob(expr *parser.QualifiedName) (
parser.QualifiedNames, error) {
if len(expr.Indirect) == 0 {
return parser.QualifiedNames{expr}, nil
}
if err := expr.QualifyWithDatabase(p.session.Database); err != nil {
return nil, err
}
// We must have a single indirect: either .table or .*
if len(expr.Indirect) != 1 {
return nil, fmt.Errorf("invalid table glob: %s", expr)
}
switch expr.Indirect[0].(type) {
case parser.NameIndirection:
return parser.QualifiedNames{expr}, nil
case parser.StarIndirection:
dbDesc, err := p.getDatabaseDesc(string(expr.Base))
if err != nil {
return nil, err
}
if dbDesc == nil {
return nil, sqlbase.NewUndefinedDatabaseError(string(expr.Base))
}
tableNames, err := p.getTableNames(dbDesc)
if err != nil {
return nil, err
}
return tableNames, nil
default:
return nil, fmt.Errorf("invalid table glob: %s", expr)
}
}