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prepare.go
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prepare.go
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// Copyright 2016 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.
package sql
import (
"bytes"
"strconv"
"unsafe"
"golang.org/x/net/context"
"github.com/cockroachdb/cockroach/pkg/sql/mon"
"github.com/cockroachdb/cockroach/pkg/sql/parser"
"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
"github.com/cockroachdb/cockroach/pkg/sql/sqlbase"
"github.com/cockroachdb/cockroach/pkg/util/uint128"
)
// PreparedStatement is a SQL statement that has been parsed and the types
// of arguments and results have been determined.
type PreparedStatement struct {
// Str is the statement string prior to parsing, used to generate
// error messages. This may be used in
// the future to present a contextual error message based on location
// information.
Str string
// Statement is the parsed, prepared SQL statement. It may be nil if the
// prepared statement is empty.
Statement parser.Statement
// TypeHints contains the types of the placeholders set by the client. It
// dictates how input parameters for those placeholders will be parsed. If a
// placeholder has no type hint, it will be populated during type checking.
TypeHints parser.PlaceholderTypes
// Types contains the final types of the placeholders, after type checking.
// These may differ from the types in TypeHints, if a user provides an
// imprecise type hint like sending an int for an oid comparison.
Types parser.PlaceholderTypes
Columns sqlbase.ResultColumns
portalNames map[string]struct{}
ProtocolMeta interface{} // a field for protocol implementations to hang metadata off of.
memAcc WrappableMemoryAccount
// constantAcc handles the allocation of various constant-folded values which
// are generated while planning the statement.
constantAcc mon.BoundAccount
}
func (p *PreparedStatement) close(ctx context.Context, s *Session) {
p.memAcc.Wsession(s).Close(ctx)
p.constantAcc.Close(ctx)
}
// Statement contains a statement with optional expected result columns and metadata.
type Statement struct {
AST parser.Statement
ExpectedTypes sqlbase.ResultColumns
queryID uint128.Uint128
queryMeta *queryMeta
}
func (s Statement) String() string {
return s.AST.String()
}
// StatementList is a list of statements.
type StatementList []Statement
// NewStatementList creates a StatementList from a parser.StatementList.
func NewStatementList(stmts parser.StatementList) StatementList {
sl := make(StatementList, len(stmts))
for i, s := range stmts {
sl[i] = Statement{AST: s}
}
return sl
}
func (l StatementList) String() string { return parser.AsString(l) }
// Format implements the NodeFormatter interface.
func (l StatementList) Format(buf *bytes.Buffer, f parser.FmtFlags) {
for i, s := range l {
if i > 0 {
buf.WriteString("; ")
}
parser.FormatNode(buf, f, s.AST)
}
}
// PreparedStatements is a mapping of PreparedStatement names to their
// corresponding PreparedStatements.
type PreparedStatements struct {
session *Session
stmts map[string]*PreparedStatement
}
func makePreparedStatements(s *Session) PreparedStatements {
return PreparedStatements{
session: s,
stmts: make(map[string]*PreparedStatement),
}
}
// Get returns the PreparedStatement with the provided name.
func (ps PreparedStatements) Get(name string) (*PreparedStatement, bool) {
stmt, ok := ps.stmts[name]
return stmt, ok
}
// Exists returns whether a PreparedStatement with the provided name exists.
func (ps PreparedStatements) Exists(name string) bool {
_, ok := ps.Get(name)
return ok
}
// NewFromString creates a new PreparedStatement with the provided name and
// corresponding query string, using the given PlaceholderTypes hints to assist
// in inferring placeholder types.
//
// ps.session.Ctx() is used as the logging context for the prepare operation.
func (ps PreparedStatements) NewFromString(
e *Executor, name, query string, placeholderHints parser.PlaceholderTypes,
) (*PreparedStatement, error) {
sessionEventf(ps.session, "parsing: %s", query)
stmts, err := parser.Parse(query)
if err != nil {
return nil, err
}
var st Statement
switch len(stmts) {
case 1:
st.AST = stmts[0]
case 0:
// ignore: nil (empty) statement.
default:
return nil, errWrongNumberOfPreparedStatements(len(stmts))
}
return ps.New(e, name, st, query, placeholderHints)
}
// New creates a new PreparedStatement with the provided name and corresponding
// query statements, using the given PlaceholderTypes hints to assist in
// inferring placeholder types.
//
// ps.session.Ctx() is used as the logging context for the prepare operation.
func (ps PreparedStatements) New(
e *Executor,
name string,
stmt Statement,
stmtStr string,
placeholderHints parser.PlaceholderTypes,
) (*PreparedStatement, error) {
// Prepare the query. This completes the typing of placeholders.
pStmt, err := e.Prepare(stmt, stmtStr, ps.session, placeholderHints)
if err != nil {
return nil, err
}
// For now we are just counting the size of the query string and
// statement name. When we start storing the prepared query plan
// during prepare, this should be tallied up to the monitor as well.
sz := int64(uintptr(len(name)+len(stmtStr)) + unsafe.Sizeof(*pStmt))
if err := pStmt.memAcc.Wsession(ps.session).OpenAndInit(ps.session.Ctx(), sz); err != nil {
return nil, err
}
if prevStmt, ok := ps.Get(name); ok {
prevStmt.close(ps.session.Ctx(), ps.session)
}
pStmt.Str = stmtStr
ps.stmts[name] = pStmt
return pStmt, nil
}
// Delete removes the PreparedStatement with the provided name from the PreparedStatements.
// The method returns whether a statement with that name was found and removed.
func (ps PreparedStatements) Delete(ctx context.Context, name string) bool {
if stmt, ok := ps.Get(name); ok {
if ps.session.PreparedPortals.portals != nil {
for portalName := range stmt.portalNames {
if portal, ok := ps.session.PreparedPortals.Get(name); ok {
delete(ps.session.PreparedPortals.portals, portalName)
portal.memAcc.Wsession(ps.session).Close(ctx)
}
}
}
stmt.close(ctx, ps.session)
delete(ps.stmts, name)
return true
}
return false
}
// closeAll de-registers all statements and portals from the monitor.
func (ps PreparedStatements) closeAll(ctx context.Context, s *Session) {
for _, stmt := range ps.stmts {
stmt.close(ctx, s)
}
for _, portal := range s.PreparedPortals.portals {
portal.memAcc.Wsession(s).Close(ctx)
}
}
// ClearStatementsAndPortals de-registers all statements and
// portals. Afterwards none can be added any more.
func (s *Session) ClearStatementsAndPortals(ctx context.Context) {
s.PreparedStatements.closeAll(ctx, s)
s.PreparedStatements.stmts = nil
s.PreparedPortals.portals = nil
}
// DeleteAll removes all PreparedStatements from the PreparedStatements. This will in turn
// remove all PreparedPortals from the session's PreparedPortals.
// This is used by the "delete" message in the pgwire protocol; after DeleteAll
// statements and portals can be added again.
func (ps *PreparedStatements) DeleteAll(ctx context.Context) {
ps.closeAll(ctx, ps.session)
ps.stmts = make(map[string]*PreparedStatement)
ps.session.PreparedPortals.portals = make(map[string]*PreparedPortal)
}
// PreparedPortal is a PreparedStatement that has been bound with query arguments.
type PreparedPortal struct {
Stmt *PreparedStatement
Qargs parser.QueryArguments
ProtocolMeta interface{} // a field for protocol implementations to hang metadata off of.
memAcc WrappableMemoryAccount
}
// PreparedPortals is a mapping of PreparedPortal names to their corresponding
// PreparedPortals.
type PreparedPortals struct {
session *Session
portals map[string]*PreparedPortal
}
func makePreparedPortals(s *Session) PreparedPortals {
return PreparedPortals{
session: s,
portals: make(map[string]*PreparedPortal),
}
}
// Get returns the PreparedPortal with the provided name.
func (pp PreparedPortals) Get(name string) (*PreparedPortal, bool) {
portal, ok := pp.portals[name]
return portal, ok
}
// Exists returns whether a PreparedPortal with the provided name exists.
func (pp PreparedPortals) Exists(name string) bool {
_, ok := pp.Get(name)
return ok
}
// New creates a new PreparedPortal with the provided name and corresponding
// PreparedStatement, binding the statement using the given QueryArguments.
func (pp PreparedPortals) New(
ctx context.Context, name string, stmt *PreparedStatement, qargs parser.QueryArguments,
) (*PreparedPortal, error) {
portal := &PreparedPortal{
Stmt: stmt,
Qargs: qargs,
}
sz := int64(uintptr(len(name)) + unsafe.Sizeof(*portal))
if err := portal.memAcc.Wsession(pp.session).OpenAndInit(ctx, sz); err != nil {
return nil, err
}
stmt.portalNames[name] = struct{}{}
if prevPortal, ok := pp.Get(name); ok {
prevPortal.memAcc.Wsession(pp.session).Close(ctx)
}
pp.portals[name] = portal
return portal, nil
}
// Delete removes the PreparedPortal with the provided name from the PreparedPortals.
// The method returns whether a portal with that name was found and removed.
func (pp PreparedPortals) Delete(ctx context.Context, name string) bool {
if portal, ok := pp.Get(name); ok {
delete(portal.Stmt.portalNames, name)
portal.memAcc.Wsession(pp.session).Close(ctx)
delete(pp.portals, name)
return true
}
return false
}
// PrepareStmt implements the PREPARE statement.
// See https://www.postgresql.org/docs/current/static/sql-prepare.html for details.
func (e *Executor) PrepareStmt(session *Session, s *parser.Prepare) error {
name := s.Name.String()
if session.PreparedStatements.Exists(name) {
return pgerror.NewErrorf(pgerror.CodeDuplicatePreparedStatementError,
"prepared statement %q already exists", name)
}
typeHints := make(parser.PlaceholderTypes, len(s.Types))
for i, t := range s.Types {
typeHints[strconv.Itoa(i+1)] = parser.CastTargetToDatumType(t)
}
_, err := session.PreparedStatements.New(
e, name, Statement{AST: s.Statement}, s.Statement.String(), typeHints,
)
return err
}
// getPreparedStatementForExecute implements the EXECUTE foo(args) SQL
// statement, returning the referenced prepared statement and correctly updated
// placeholder info.
// See https://www.postgresql.org/docs/current/static/sql-execute.html for details.
func getPreparedStatementForExecute(
session *Session, s *parser.Execute,
) (ps *PreparedStatement, pInfo *parser.PlaceholderInfo, err error) {
name := s.Name.String()
prepared, ok := session.PreparedStatements.Get(name)
if !ok {
return ps, pInfo, pgerror.NewErrorf(pgerror.CodeInvalidSQLStatementNameError,
"prepared statement %q does not exist", name)
}
if len(prepared.TypeHints) != len(s.Params) {
return ps, pInfo, pgerror.NewErrorf(pgerror.CodeSyntaxError,
"wrong number of parameters for prepared statement %q: expected %d, got %d",
name, len(prepared.TypeHints), len(s.Params))
}
qArgs := make(parser.QueryArguments, len(s.Params))
var p parser.Parser
for i, e := range s.Params {
idx := strconv.Itoa(i + 1)
typedExpr, err := sqlbase.SanitizeVarFreeExpr(e, prepared.TypeHints[idx], "EXECUTE parameter", session.SearchPath)
if err != nil {
return ps, pInfo, pgerror.NewError(pgerror.CodeWrongObjectTypeError, err.Error())
}
if err := p.AssertNoAggregationOrWindowing(typedExpr, "EXECUTE parameters", session.SearchPath); err != nil {
return ps, pInfo, err
}
qArgs[idx] = typedExpr
}
return prepared, &parser.PlaceholderInfo{Values: qArgs, TypeHints: prepared.TypeHints, Types: prepared.Types}, nil
}
// Deallocate implements the DEALLOCATE statement.
// See https://www.postgresql.org/docs/current/static/sql-deallocate.html for details.
func (p *planner) Deallocate(ctx context.Context, s *parser.Deallocate) (planNode, error) {
if s.Name == "" {
p.session.PreparedStatements.DeleteAll(ctx)
} else {
if found := p.session.PreparedStatements.Delete(ctx, string(s.Name)); !found {
return nil, pgerror.NewErrorf(pgerror.CodeInvalidSQLStatementNameError,
"prepared statement %q does not exist", s.Name)
}
}
return &zeroNode{}, nil
}
// Execute creates a plan for an execute statement by substituting the plan for
// the prepared statement. This is not called in normal circumstances by
// the executor - it merely exists to enable explains and traces for execute
// statements.
func (p *planner) Execute(ctx context.Context, n *parser.Execute) (planNode, error) {
ps, newPInfo, err := getPreparedStatementForExecute(p.session, n)
if err != nil {
return nil, err
}
p.semaCtx.Placeholders.Assign(newPInfo)
return p.newPlan(ctx, ps.Statement, nil)
}