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update.go
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update.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)
package sql
import (
"fmt"
"golang.org/x/net/context"
"github.com/cockroachdb/cockroach/pkg/roachpb"
"github.com/cockroachdb/cockroach/pkg/sql/parser"
"github.com/cockroachdb/cockroach/pkg/sql/privilege"
"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
"github.com/cockroachdb/cockroach/pkg/util/tracing"
"github.com/pkg/errors"
)
// editNode (Base, Run) is shared between all row updating
// statements (DELETE, UPDATE, INSERT).
// editNodeBase holds the common (prepare+execute) state needed to run
// row-modifying statements.
type editNodeBase struct {
p *planner
rh *returningHelper
tableDesc *sqlbase.TableDescriptor
}
func (p *planner) makeEditNode(
ctx context.Context, tn *parser.TableName, priv privilege.Kind,
) (editNodeBase, error) {
tableDesc, err := p.session.leases.getTableLease(ctx, p.txn, p.getVirtualTabler(), tn)
if err != nil {
return editNodeBase{}, err
}
// We don't support update on views, only real tables.
if !tableDesc.IsTable() {
return editNodeBase{},
errors.Errorf("cannot run %s on view %q - views are not updateable", priv, tn)
}
if err := p.CheckPrivilege(tableDesc, priv); err != nil {
return editNodeBase{}, err
}
return editNodeBase{
p: p,
tableDesc: tableDesc,
}, nil
}
// editNodeRun holds the runtime (execute) state needed to run
// row-modifying statements.
type editNodeRun struct {
rows planNode
tw tableWriter
resultRow parser.Datums
explain explainMode
}
func (r *editNodeRun) initEditNode(
ctx context.Context,
en *editNodeBase,
rows planNode,
tw tableWriter,
re parser.ReturningClause,
desiredTypes []parser.Type,
) error {
r.rows = rows
r.tw = tw
rh, err := en.p.newReturningHelper(ctx, re, desiredTypes, en.tableDesc.Name, en.tableDesc.Columns)
if err != nil {
return err
}
en.rh = rh
return nil
}
func (r *editNodeRun) startEditNode(ctx context.Context, en *editNodeBase) error {
if sqlbase.IsSystemConfigID(en.tableDesc.GetID()) {
// Mark transaction as operating on the system DB.
if err := en.p.txn.SetSystemConfigTrigger(); err != nil {
return err
}
}
return r.rows.Start(ctx)
}
func (r *editNodeRun) collectSpans(ctx context.Context) (reads, writes roachpb.Spans, err error) {
scanReads, scanWrites, err := r.rows.Spans(ctx)
if err != nil {
return nil, nil, err
}
if len(scanWrites) > 0 {
return nil, nil, errors.Errorf("unexpected scan span writes: %v", scanWrites)
}
// TODO(nvanbenschoten): if we notice that r.rows is a ValuesClause, we
// may be able to contrain the tableWriter Spans.
writerReads, writerWrites, err := r.tw.spans()
if err != nil {
return nil, nil, err
}
sqReads, err := collectSubquerySpans(ctx, r.rows)
if err != nil {
return nil, nil, err
}
return append(scanReads, append(writerReads, sqReads...)...), writerWrites, nil
}
type updateNode struct {
// The following fields are populated during makePlan.
editNodeBase
n *parser.Update
updateCols []sqlbase.ColumnDescriptor
updateColsIdx map[sqlbase.ColumnID]int // index in updateCols slice
tw tableUpdater
checkHelper checkHelper
sourceSlots []sourceSlot
run struct {
// The following fields are populated during Start().
editNodeRun
}
}
// sourceSlot abstracts the idea that our update sources can either be tuples
// or scalars. Tuples are for cases such as SET (a, b) = (1, 2) or SET (a, b) =
// (SELECT 1, 2), and scalars are for situations like SET a = b. A sourceSlot
// represents how to extract and type-check the results of the right-hand side
// of a single SET statement. We could treat everything as tuples, including
// scalars as tuples of size 1, and eliminate this indirection, but that makes
// the query plan more complex.
type sourceSlot interface {
// extractValues returns a slice of the values this slot is responsible for,
// as extracted from the row of results.
extractValues(resultRow parser.Datums) parser.Datums
// checkColumnTypes compares the types of the results that this slot refers to to the types of
// the columns those values will be assigned to. It returns an error if those types don't match up.
// It also populates the types of any placeholders by way of calling into sqlbase.CheckColumnType.
checkColumnTypes(row []parser.TypedExpr, pmap *parser.PlaceholderInfo) error
}
type tupleSlot struct {
columns []sqlbase.ColumnDescriptor
sourceIndex int
}
func (ts tupleSlot) extractValues(row parser.Datums) parser.Datums {
return row[ts.sourceIndex].(*parser.DTuple).D
}
func (ts tupleSlot) checkColumnTypes(row []parser.TypedExpr, pmap *parser.PlaceholderInfo) error {
renderedResult := row[ts.sourceIndex]
for i, typ := range renderedResult.ResolvedType().(parser.TTuple) {
if err := sqlbase.CheckColumnType(ts.columns[i], typ, pmap); err != nil {
return err
}
}
return nil
}
type scalarSlot struct {
column sqlbase.ColumnDescriptor
sourceIndex int
}
func (ss scalarSlot) extractValues(row parser.Datums) parser.Datums {
return row[ss.sourceIndex : ss.sourceIndex+1]
}
func (ss scalarSlot) checkColumnTypes(row []parser.TypedExpr, pmap *parser.PlaceholderInfo) error {
renderedResult := row[ss.sourceIndex]
typ := renderedResult.ResolvedType()
return sqlbase.CheckColumnType(ss.column, typ, pmap)
}
// addOrMergeExpr inserts an Expr into a renderNode, attempting to reuse
// previous renders if possible by using render.addOrMergeRender, returning the
// column index at which the rendered value can be accessed.
func addOrMergeExpr(
ctx context.Context,
e parser.Expr,
currentUpdateIdx int,
updateCols []sqlbase.ColumnDescriptor,
defaultExprs []parser.TypedExpr,
render *renderNode,
) (colIdx int, err error) {
e = fillDefault(e, currentUpdateIdx, defaultExprs)
selectExpr := parser.SelectExpr{Expr: e}
typ := updateCols[currentUpdateIdx].Type.ToDatumType()
col, expr, err := render.planner.computeRender(ctx, selectExpr, typ,
render.sourceInfo, render.ivarHelper, autoGenerateRenderOutputName)
if err != nil {
return -1, err
}
return render.addOrMergeRender(col, expr, true), nil
}
// Update updates columns for a selection of rows from a table.
// Privileges: UPDATE and SELECT on table. We currently always use a select statement.
// Notes: postgres requires UPDATE. Requires SELECT with WHERE clause with table.
// mysql requires UPDATE. Also requires SELECT with WHERE clause with table.
// TODO(guanqun): need to support CHECK in UPDATE
func (p *planner) Update(
ctx context.Context, n *parser.Update, desiredTypes []parser.Type,
) (planNode, error) {
tracing.AnnotateTrace()
tn, err := p.getAliasedTableName(n.Table)
if err != nil {
return nil, err
}
en, err := p.makeEditNode(ctx, tn, privilege.UPDATE)
if err != nil {
return nil, err
}
setExprs := make([]*parser.UpdateExpr, len(n.Exprs))
for i, expr := range n.Exprs {
// Replace the sub-query nodes.
newExpr, err := p.replaceSubqueries(ctx, expr.Expr, len(expr.Names))
if err != nil {
return nil, err
}
setExprs[i] = &parser.UpdateExpr{Tuple: expr.Tuple, Expr: newExpr, Names: expr.Names}
}
// Determine which columns we're inserting into.
names, err := p.namesForExprs(setExprs)
if err != nil {
return nil, err
}
updateCols, err := p.processColumns(en.tableDesc, names)
if err != nil {
return nil, err
}
defaultExprs, err := sqlbase.MakeDefaultExprs(updateCols, &p.parser, &p.evalCtx)
if err != nil {
return nil, err
}
var requestedCols []sqlbase.ColumnDescriptor
if _, retExprs := n.Returning.(*parser.ReturningExprs); retExprs || len(en.tableDesc.Checks) > 0 {
// TODO(dan): This could be made tighter, just the rows needed for RETURNING
// exprs.
requestedCols = en.tableDesc.Columns
}
fkTables := sqlbase.TablesNeededForFKs(*en.tableDesc, sqlbase.CheckUpdates)
if err := p.fillFKTableMap(ctx, fkTables); err != nil {
return nil, err
}
ru, err := sqlbase.MakeRowUpdater(p.txn, en.tableDesc, fkTables, updateCols, requestedCols, sqlbase.RowUpdaterDefault)
if err != nil {
return nil, err
}
tw := tableUpdater{ru: ru, autoCommit: p.autoCommit}
tracing.AnnotateTrace()
// We construct a query containing the columns being updated, and then later merge the values
// they are being updated with into that renderNode to ideally reuse some of the queries.
rows, err := p.SelectClause(ctx, &parser.SelectClause{
Exprs: sqlbase.ColumnsSelectors(ru.FetchCols),
From: &parser.From{Tables: []parser.TableExpr{n.Table}},
Where: n.Where,
}, nil, nil, nil, publicAndNonPublicColumns)
if err != nil {
return nil, err
}
// This capacity is an overestimate, since subqueries only take up one sourceSlot.
sourceSlots := make([]sourceSlot, 0, len(ru.FetchCols))
// currentUpdateIdx is the index of the first column descriptor in updateCols
// that is assigned to by the current setExpr.
currentUpdateIdx := 0
render := rows.(*renderNode)
for _, setExpr := range setExprs {
if setExpr.Tuple {
switch t := setExpr.Expr.(type) {
case *parser.Tuple:
// The user assigned an explicit set of values to the columns. We can't
// treat this case the same as when we have a subquery (and just evaluate
// the tuple) because when assigning a literal tuple like this it's valid
// to assign DEFAULT to some of the columns, which is not valid generally.
for _, e := range t.Exprs {
colIdx, err := addOrMergeExpr(ctx, e, currentUpdateIdx, updateCols, defaultExprs, render)
if err != nil {
return nil, err
}
sourceSlots = append(sourceSlots, scalarSlot{
column: updateCols[currentUpdateIdx],
sourceIndex: colIdx,
})
currentUpdateIdx++
}
case *subquery:
selectExpr := parser.SelectExpr{Expr: t}
desiredTupleType := make(parser.TTuple, len(setExpr.Names))
for i := range setExpr.Names {
desiredTupleType[i] = updateCols[currentUpdateIdx+i].Type.ToDatumType()
}
col, expr, err := render.planner.computeRender(ctx, selectExpr, desiredTupleType,
render.sourceInfo, render.ivarHelper, autoGenerateRenderOutputName)
if err != nil {
return nil, err
}
colIdx := render.addOrMergeRender(col, expr, false)
sourceSlots = append(sourceSlots, tupleSlot{
columns: updateCols[currentUpdateIdx : currentUpdateIdx+len(setExpr.Names)],
sourceIndex: colIdx,
})
currentUpdateIdx += len(setExpr.Names)
default:
panic(fmt.Sprintf("assigning to tuple with expression that is neither a tuple nor a subquery: %s", setExpr.Expr))
}
} else {
colIdx, err := addOrMergeExpr(ctx, setExpr.Expr, currentUpdateIdx, updateCols, defaultExprs, render)
if err != nil {
return nil, err
}
sourceSlots = append(sourceSlots, scalarSlot{
column: updateCols[currentUpdateIdx],
sourceIndex: colIdx,
})
currentUpdateIdx++
}
}
// Placeholders have their types populated in the above Select if they are part
// of an expression ("SET a = 2 + $1") in the type check step where those
// types are inferred. For the simpler case ("SET a = $1"), populate them
// using checkColumnType. This step also verifies that the expression
// types match the column types.
sel := rows.(*renderNode)
for _, sourceSlot := range sourceSlots {
if err := sourceSlot.checkColumnTypes(sel.render, &p.semaCtx.Placeholders); err != nil {
return nil, err
}
}
updateColsIdx := make(map[sqlbase.ColumnID]int, len(ru.UpdateCols))
for i, col := range ru.UpdateCols {
updateColsIdx[col.ID] = i
}
un := &updateNode{
n: n,
editNodeBase: en,
updateCols: ru.UpdateCols,
updateColsIdx: updateColsIdx,
tw: tw,
sourceSlots: sourceSlots,
}
if err := un.checkHelper.init(ctx, p, tn, en.tableDesc); err != nil {
return nil, err
}
if err := un.run.initEditNode(
ctx, &un.editNodeBase, rows, &un.tw, n.Returning, desiredTypes); err != nil {
return nil, err
}
return un, nil
}
func (u *updateNode) Start(ctx context.Context) error {
if err := u.run.startEditNode(ctx, &u.editNodeBase); err != nil {
return err
}
return u.run.tw.init(u.p.txn)
}
func (u *updateNode) Close(ctx context.Context) {
u.run.rows.Close(ctx)
}
func (u *updateNode) Next(ctx context.Context) (bool, error) {
next, err := u.run.rows.Next(ctx)
if !next {
if err == nil {
// We're done. Finish the batch.
err = u.tw.finalize(ctx)
}
return false, err
}
if u.run.explain == explainDebug {
return true, nil
}
tracing.AnnotateTrace()
entireRow := u.run.rows.Values()
// Our updated value expressions occur immediately after the plain
// columns in the output.
oldValues := entireRow[:len(u.tw.ru.FetchCols)]
updateValues := make(parser.Datums, len(u.tw.ru.UpdateCols))
valueIdx := 0
for _, slot := range u.sourceSlots {
for _, value := range slot.extractValues(entireRow) {
updateValues[valueIdx] = value
valueIdx++
}
}
if err := u.checkHelper.loadRow(u.tw.ru.FetchColIDtoRowIndex, oldValues, false); err != nil {
return false, err
}
if err := u.checkHelper.loadRow(u.updateColsIdx, updateValues, true); err != nil {
return false, err
}
if err := u.checkHelper.check(&u.p.evalCtx); err != nil {
return false, err
}
// Ensure that the values honor the specified column widths.
for i := range updateValues {
if err := sqlbase.CheckValueWidth(u.tw.ru.UpdateCols[i], updateValues[i]); err != nil {
return false, err
}
}
for i, col := range u.tw.ru.UpdateCols {
val := updateValues[i]
if !col.Nullable && val == parser.DNull {
return false, sqlbase.NewNonNullViolationError(col.Name)
}
}
// Update the row values.
newValues, err := u.tw.row(ctx, append(oldValues, updateValues...))
if err != nil {
return false, err
}
resultRow, err := u.rh.cookResultRow(newValues)
if err != nil {
return false, err
}
u.run.resultRow = resultRow
return true, nil
}
// namesForExprs expands names in the tuples and subqueries in exprs.
func (p *planner) namesForExprs(exprs parser.UpdateExprs) (parser.UnresolvedNames, error) {
var names parser.UnresolvedNames
for _, expr := range exprs {
if expr.Tuple {
n := -1
switch t := expr.Expr.(type) {
case *subquery:
if tup, ok := t.typ.(parser.TTuple); ok {
n = len(tup)
}
case *parser.Tuple:
n = len(t.Exprs)
case *parser.DTuple:
n = len(t.D)
}
if n < 0 {
return nil, errors.Errorf("unsupported tuple assignment: %T", expr.Expr)
}
if len(expr.Names) != n {
return nil, fmt.Errorf("number of columns (%d) does not match number of values (%d)",
len(expr.Names), n)
}
}
names = append(names, expr.Names...)
}
return names, nil
}
func fillDefault(expr parser.Expr, index int, defaultExprs []parser.TypedExpr) parser.Expr {
switch expr.(type) {
case parser.DefaultVal:
if defaultExprs == nil {
return parser.DNull
}
return defaultExprs[index]
}
return expr
}
func (u *updateNode) Columns() sqlbase.ResultColumns {
return u.rh.columns
}
func (u *updateNode) Values() parser.Datums {
return u.run.resultRow
}
func (u *updateNode) MarkDebug(mode explainMode) {
if mode != explainDebug {
panic(fmt.Sprintf("unknown debug mode %d", mode))
}
u.run.explain = mode
u.run.rows.MarkDebug(mode)
}
func (u *updateNode) DebugValues() debugValues {
return u.run.rows.DebugValues()
}
func (u *updateNode) Ordering() orderingInfo { return orderingInfo{} }
func (u *updateNode) Spans(ctx context.Context) (reads, writes roachpb.Spans, err error) {
return u.run.collectSpans(ctx)
}