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conn_executor_exec.go
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/
conn_executor_exec.go
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// Copyright 2018 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.
package sql
import (
"bytes"
"context"
"encoding/base64"
"fmt"
"runtime/pprof"
"strconv"
"strings"
"time"
"github.com/cockroachdb/cockroach/pkg/jobs"
"github.com/cockroachdb/cockroach/pkg/kv"
"github.com/cockroachdb/cockroach/pkg/multitenant"
"github.com/cockroachdb/cockroach/pkg/multitenant/multitenantcpu"
"github.com/cockroachdb/cockroach/pkg/roachpb"
"github.com/cockroachdb/cockroach/pkg/server/telemetry"
"github.com/cockroachdb/cockroach/pkg/settings/cluster"
"github.com/cockroachdb/cockroach/pkg/sql/catalog/colinfo"
"github.com/cockroachdb/cockroach/pkg/sql/catalog/descs"
"github.com/cockroachdb/cockroach/pkg/sql/clusterunique"
"github.com/cockroachdb/cockroach/pkg/sql/contentionpb"
"github.com/cockroachdb/cockroach/pkg/sql/delegate"
"github.com/cockroachdb/cockroach/pkg/sql/execinfrapb"
"github.com/cockroachdb/cockroach/pkg/sql/execstats"
"github.com/cockroachdb/cockroach/pkg/sql/opt/exec/explain"
"github.com/cockroachdb/cockroach/pkg/sql/paramparse"
"github.com/cockroachdb/cockroach/pkg/sql/parser"
"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
"github.com/cockroachdb/cockroach/pkg/sql/physicalplan"
"github.com/cockroachdb/cockroach/pkg/sql/rowenc"
"github.com/cockroachdb/cockroach/pkg/sql/sem/eval"
"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
"github.com/cockroachdb/cockroach/pkg/sql/sessiondatapb"
"github.com/cockroachdb/cockroach/pkg/sql/sessionphase"
"github.com/cockroachdb/cockroach/pkg/sql/sqlerrors"
"github.com/cockroachdb/cockroach/pkg/sql/sqlstats"
"github.com/cockroachdb/cockroach/pkg/sql/sqltelemetry"
"github.com/cockroachdb/cockroach/pkg/sql/types"
"github.com/cockroachdb/cockroach/pkg/util"
"github.com/cockroachdb/cockroach/pkg/util/buildutil"
"github.com/cockroachdb/cockroach/pkg/util/cancelchecker"
"github.com/cockroachdb/cockroach/pkg/util/contextutil"
"github.com/cockroachdb/cockroach/pkg/util/duration"
"github.com/cockroachdb/cockroach/pkg/util/fsm"
"github.com/cockroachdb/cockroach/pkg/util/hlc"
"github.com/cockroachdb/cockroach/pkg/util/log"
"github.com/cockroachdb/cockroach/pkg/util/log/eventpb"
"github.com/cockroachdb/cockroach/pkg/util/log/logpb"
"github.com/cockroachdb/cockroach/pkg/util/metric"
"github.com/cockroachdb/cockroach/pkg/util/timeutil"
"github.com/cockroachdb/cockroach/pkg/util/tracing"
"github.com/cockroachdb/cockroach/pkg/util/tracing/tracingpb"
"github.com/cockroachdb/cockroach/pkg/util/uuid"
"github.com/cockroachdb/errors"
"github.com/lib/pq/oid"
"go.opentelemetry.io/otel/attribute"
)
// execStmt executes one statement by dispatching according to the current
// state. Returns an Event to be passed to the state machine, or nil if no
// transition is needed. If nil is returned, then the cursor is supposed to
// advance to the next statement.
//
// If an error is returned, the session is supposed to be considered done. Query
// execution errors are not returned explicitly and they're also not
// communicated to the client. Instead they're incorporated in the returned
// event (the returned payload will implement payloadWithError). It is the
// caller's responsibility to deliver execution errors to the client.
//
// Args:
// stmt: The statement to execute.
// res: Used to produce query results.
// pinfo: The values to use for the statement's placeholders. If nil is passed,
//
// then the statement cannot have any placeholder.
func (ex *connExecutor) execStmt(
ctx context.Context,
parserStmt parser.Statement,
prepared *PreparedStatement,
pinfo *tree.PlaceholderInfo,
res RestrictedCommandResult,
canAutoCommit bool,
) (fsm.Event, fsm.EventPayload, error) {
ast := parserStmt.AST
if log.V(2) || logStatementsExecuteEnabled.Get(&ex.server.cfg.Settings.SV) ||
log.HasSpanOrEvent(ctx) {
log.VEventf(ctx, 2, "executing: %s in state: %s", ast, ex.machine.CurState())
}
// Stop the session idle timeout when a new statement is executed.
ex.mu.IdleInSessionTimeout.Stop()
ex.mu.IdleInTransactionSessionTimeout.Stop()
// Run observer statements in a separate code path; their execution does not
// depend on the current transaction state.
if _, ok := ast.(tree.ObserverStatement); ok {
ex.statsCollector.Reset(ex.applicationStats, ex.phaseTimes)
err := ex.runObserverStatement(ctx, ast, res)
// Note that regardless of res.Err(), these observer statements don't
// generate error events; transactions are always allowed to continue.
return nil, nil, err
}
// Dispatch the statement for execution based on the current state.
var ev fsm.Event
var payload fsm.EventPayload
var err error
switch ex.machine.CurState().(type) {
case stateNoTxn:
// Note: when not using explicit transactions, we go through this transition
// for every statement. It is important to minimize the amount of work and
// allocations performed up to this point.
ev, payload = ex.execStmtInNoTxnState(ctx, ast)
case stateOpen:
err = ex.execWithProfiling(ctx, ast, prepared, func(ctx context.Context) error {
ev, payload, err = ex.execStmtInOpenState(ctx, parserStmt, prepared, pinfo, res, canAutoCommit)
return err
})
switch ev.(type) {
case eventNonRetriableErr:
ex.recordFailure()
}
case stateAborted:
ev, payload = ex.execStmtInAbortedState(ctx, ast, res)
case stateCommitWait:
ev, payload = ex.execStmtInCommitWaitState(ctx, ast, res)
default:
panic(errors.AssertionFailedf("unexpected txn state: %#v", ex.machine.CurState()))
}
if ex.sessionData().IdleInSessionTimeout > 0 {
// Cancel the session if the idle time exceeds the idle in session timeout.
ex.mu.IdleInSessionTimeout = timeout{time.AfterFunc(
ex.sessionData().IdleInSessionTimeout,
ex.cancelSession,
)}
}
if ex.sessionData().IdleInTransactionSessionTimeout > 0 {
startIdleInTransactionSessionTimeout := func() {
switch ast.(type) {
case *tree.CommitTransaction, *tree.RollbackTransaction:
// Do nothing, the transaction is completed, we do not want to start
// an idle timer.
default:
ex.mu.IdleInTransactionSessionTimeout = timeout{time.AfterFunc(
ex.sessionData().IdleInTransactionSessionTimeout,
ex.cancelSession,
)}
}
}
switch ex.machine.CurState().(type) {
case stateAborted, stateCommitWait:
startIdleInTransactionSessionTimeout()
case stateOpen:
// Only start timeout if the statement is executed in an
// explicit transaction.
if !ex.implicitTxn() {
startIdleInTransactionSessionTimeout()
}
}
}
return ev, payload, err
}
func (ex *connExecutor) recordFailure() {
ex.metrics.EngineMetrics.FailureCount.Inc(1)
}
// execPortal executes a prepared statement. It is a "wrapper" around execStmt
// method that is performing additional work to track portal's state.
func (ex *connExecutor) execPortal(
ctx context.Context,
portal PreparedPortal,
portalName string,
stmtRes CommandResult,
pinfo *tree.PlaceholderInfo,
canAutoCommit bool,
) (ev fsm.Event, payload fsm.EventPayload, err error) {
switch ex.machine.CurState().(type) {
case stateOpen:
// We're about to execute the statement in an open state which
// could trigger the dispatch to the execution engine. However, it
// is possible that we're trying to execute an already exhausted
// portal - in such a scenario we should return no rows, but the
// execution engine is not aware of that and would run the
// statement as if it was running it for the first time. In order
// to prevent such behavior, we check whether the portal has been
// exhausted and execute the statement only if it hasn't. If it has
// been exhausted, then we do not dispatch the query for execution,
// but connExecutor will still perform necessary state transitions
// which will emit CommandComplete messages and alike (in a sense,
// by not calling execStmt we "execute" the portal in such a way
// that it returns 0 rows).
// Note that here we deviate from Postgres which returns an error
// when attempting to execute an exhausted portal which has a
// StatementReturnType() different from "Rows".
if portal.exhausted {
return nil, nil, nil
}
ev, payload, err = ex.execStmt(ctx, portal.Stmt.Statement, portal.Stmt, pinfo, stmtRes, canAutoCommit)
// Portal suspension is supported via a "side" state machine
// (see pgwire.limitedCommandResult for details), so when
// execStmt returns, we know for sure that the portal has been
// executed to completion, thus, it is exhausted.
// Note that the portal is considered exhausted regardless of
// the fact whether an error occurred or not - if it did, we
// still don't want to re-execute the portal from scratch.
// The current statement may have just closed and deleted the portal,
// so only exhaust it if it still exists.
if _, ok := ex.extraTxnState.prepStmtsNamespace.portals[portalName]; ok {
ex.exhaustPortal(portalName)
}
return ev, payload, err
default:
return ex.execStmt(ctx, portal.Stmt.Statement, portal.Stmt, pinfo, stmtRes, canAutoCommit)
}
}
// execStmtInOpenState executes one statement in the context of the session's
// current transaction.
// It handles statements that affect the transaction state (BEGIN, COMMIT)
// directly and delegates everything else to the execution engines.
// Results and query execution errors are written to res.
//
// This method also handles "auto commit" - committing of implicit transactions.
//
// If an error is returned, the connection is supposed to be consider done.
// Query execution errors are not returned explicitly; they're incorporated in
// the returned Event.
//
// The returned event can be nil if no state transition is required.
func (ex *connExecutor) execStmtInOpenState(
ctx context.Context,
parserStmt parser.Statement,
prepared *PreparedStatement,
pinfo *tree.PlaceholderInfo,
res RestrictedCommandResult,
canAutoCommit bool,
) (retEv fsm.Event, retPayload fsm.EventPayload, retErr error) {
ctx, sp := tracing.EnsureChildSpan(ctx, ex.server.cfg.AmbientCtx.Tracer, "sql query")
// TODO(andrei): Consider adding the placeholders as tags too.
sp.SetTag("statement", attribute.StringValue(parserStmt.SQL))
defer sp.Finish()
ast := parserStmt.AST
ctx = withStatement(ctx, ast)
makeErrEvent := func(err error) (fsm.Event, fsm.EventPayload, error) {
ev, payload := ex.makeErrEvent(err, ast)
return ev, payload, nil
}
var stmt Statement
queryID := ex.generateID()
// Update the deadline on the transaction based on the collections.
err := ex.extraTxnState.descCollection.MaybeUpdateDeadline(ctx, ex.state.mu.txn)
if err != nil {
return makeErrEvent(err)
}
os := ex.machine.CurState().(stateOpen)
isExtendedProtocol := prepared != nil
if isExtendedProtocol {
stmt = makeStatementFromPrepared(prepared, queryID)
} else {
stmt = makeStatement(parserStmt, queryID)
}
ex.incrementStartedStmtCounter(ast)
defer func() {
if retErr == nil && !payloadHasError(retPayload) {
ex.incrementExecutedStmtCounter(ast)
}
}()
func(st *txnState) {
st.mu.Lock()
defer st.mu.Unlock()
st.mu.stmtCount++
}(&ex.state)
var timeoutTicker *time.Timer
queryTimedOut := false
// doneAfterFunc will be allocated only when timeoutTicker is non-nil.
var doneAfterFunc chan struct{}
// Early-associate placeholder info with the eval context,
// so that we can fill in placeholder values in our call to addActiveQuery, below.
if !ex.planner.EvalContext().HasPlaceholders() {
ex.planner.EvalContext().Placeholders = pinfo
}
var cancelQuery context.CancelFunc
ctx, cancelQuery = contextutil.WithCancel(ctx)
ex.addActiveQuery(ast, formatWithPlaceholders(ast, ex.planner.EvalContext()), queryID, cancelQuery)
// Make sure that we always unregister the query. It also deals with
// overwriting res.Error to a more user-friendly message in case of query
// cancellation.
defer func(ctx context.Context, res RestrictedCommandResult) {
if timeoutTicker != nil {
if !timeoutTicker.Stop() {
// Wait for the timer callback to complete to avoid a data race on
// queryTimedOut.
<-doneAfterFunc
}
}
// Detect context cancelation and overwrite whatever error might have been
// set on the result before. The idea is that once the query's context is
// canceled, all sorts of actors can detect the cancelation and set all
// sorts of errors on the result. Rather than trying to impose discipline
// in that jungle, we just overwrite them all here with an error that's
// nicer to look at for the client.
if res != nil && ctx.Err() != nil && res.Err() != nil {
// Even in the cases where the error is a retryable error, we want to
// intercept the event and payload returned here to ensure that the query
// is not retried.
retEv = eventNonRetriableErr{
IsCommit: fsm.FromBool(isCommit(ast)),
}
res.SetError(cancelchecker.QueryCanceledError)
retPayload = eventNonRetriableErrPayload{err: cancelchecker.QueryCanceledError}
}
ex.removeActiveQuery(queryID, ast)
cancelQuery()
if ex.executorType != executorTypeInternal {
ex.metrics.EngineMetrics.SQLActiveStatements.Dec(1)
}
// If the query timed out, we intercept the error, payload, and event here
// for the same reasons we intercept them for canceled queries above.
// Overriding queries with a QueryTimedOut error needs to happen after
// we've checked for canceled queries as some queries may be canceled
// because of a timeout, in which case the appropriate error to return to
// the client is one that indicates the timeout, rather than the more general
// query canceled error. It's important to note that a timed out query may
// not have been canceled (eg. We never even start executing a query
// because the timeout has already expired), and therefore this check needs
// to happen outside the canceled query check above.
if queryTimedOut {
// A timed out query should never produce retryable errors/events/payloads
// so we intercept and overwrite them all here.
retEv = eventNonRetriableErr{
IsCommit: fsm.FromBool(isCommit(ast)),
}
res.SetError(sqlerrors.QueryTimeoutError)
retPayload = eventNonRetriableErrPayload{err: sqlerrors.QueryTimeoutError}
}
}(ctx, res)
if ex.executorType != executorTypeInternal {
ex.metrics.EngineMetrics.SQLActiveStatements.Inc(1)
}
p := &ex.planner
stmtTS := ex.server.cfg.Clock.PhysicalTime()
ex.statsCollector.Reset(ex.applicationStats, ex.phaseTimes)
ex.resetPlanner(ctx, p, ex.state.mu.txn, stmtTS)
p.sessionDataMutatorIterator.paramStatusUpdater = res
p.noticeSender = res
ih := &p.instrumentation
// Special top-level handling for EXPLAIN ANALYZE.
if e, ok := ast.(*tree.ExplainAnalyze); ok {
switch e.Mode {
case tree.ExplainDebug:
telemetry.Inc(sqltelemetry.ExplainAnalyzeDebugUseCounter)
ih.SetOutputMode(explainAnalyzeDebugOutput, explain.Flags{})
case tree.ExplainPlan:
telemetry.Inc(sqltelemetry.ExplainAnalyzeUseCounter)
flags := explain.MakeFlags(&e.ExplainOptions)
if ex.server.cfg.TestingKnobs.DeterministicExplain {
flags.Redact = explain.RedactAll
}
ih.SetOutputMode(explainAnalyzePlanOutput, flags)
case tree.ExplainDistSQL:
telemetry.Inc(sqltelemetry.ExplainAnalyzeDistSQLUseCounter)
flags := explain.MakeFlags(&e.ExplainOptions)
if ex.server.cfg.TestingKnobs.DeterministicExplain {
flags.Redact = explain.RedactAll
}
ih.SetOutputMode(explainAnalyzeDistSQLOutput, flags)
default:
return makeErrEvent(errors.AssertionFailedf("unsupported EXPLAIN ANALYZE mode %s", e.Mode))
}
// Strip off the explain node to execute the inner statement.
stmt.AST = e.Statement
ast = e.Statement
// TODO(radu): should we trim the "EXPLAIN ANALYZE (DEBUG)" part from
// stmt.SQL?
// Clear any ExpectedTypes we set if we prepared this statement (they
// reflect the column types of the EXPLAIN itself and not those of the inner
// statement).
stmt.ExpectedTypes = nil
}
// Special top-level handling for EXECUTE. This must happen after the handling
// for EXPLAIN ANALYZE (in order to support EXPLAIN ANALYZE EXECUTE) but
// before setting up the instrumentation helper.
if e, ok := ast.(*tree.Execute); ok {
// Replace the `EXECUTE foo` statement with the prepared statement, and
// continue execution.
name := e.Name.String()
ps, ok := ex.extraTxnState.prepStmtsNamespace.prepStmts[name]
if !ok {
return makeErrEvent(newPreparedStmtDNEError(ex.sessionData(), name))
}
ex.extraTxnState.prepStmtsNamespace.touchLRUEntry(name)
var err error
pinfo, err = ex.planner.fillInPlaceholders(ctx, ps, name, e.Params)
if err != nil {
return makeErrEvent(err)
}
// TODO(radu): what about .SQL, .NumAnnotations, .NumPlaceholders?
stmt.Statement = ps.Statement
stmt.Prepared = ps
stmt.ExpectedTypes = ps.Columns
stmt.StmtNoConstants = ps.StatementNoConstants
stmt.StmtSummary = ps.StatementSummary
res.ResetStmtType(ps.AST)
if e.DiscardRows {
ih.SetDiscardRows()
}
ast = stmt.Statement.AST
}
var needFinish bool
ctx, needFinish = ih.Setup(
ctx, ex.server.cfg, ex.statsCollector, p, ex.stmtDiagnosticsRecorder,
stmt.StmtNoConstants, os.ImplicitTxn.Get(), ex.extraTxnState.shouldCollectTxnExecutionStats,
)
if needFinish {
sql := stmt.SQL
defer func() {
retErr = ih.Finish(
ex.server.cfg,
ex.statsCollector,
&ex.extraTxnState.accumulatedStats,
ih.collectExecStats,
p,
ast,
sql,
res,
retPayload,
retErr,
)
}()
// TODO(radu): consider removing this if/when #46164 is addressed.
p.extendedEvalCtx.Context.Context = ctx
}
// We exempt `SET` statements from the statement timeout, particularly so as
// not to block the `SET statement_timeout` command itself.
if ex.sessionData().StmtTimeout > 0 && ast.StatementTag() != "SET" {
timerDuration :=
ex.sessionData().StmtTimeout - timeutil.Since(ex.phaseTimes.GetSessionPhaseTime(sessionphase.SessionQueryReceived))
// There's no need to proceed with execution if the timer has already expired.
if timerDuration < 0 {
queryTimedOut = true
return makeErrEvent(sqlerrors.QueryTimeoutError)
}
doneAfterFunc = make(chan struct{}, 1)
timeoutTicker = time.AfterFunc(
timerDuration,
func() {
cancelQuery()
queryTimedOut = true
doneAfterFunc <- struct{}{}
})
}
defer func(ctx context.Context) {
if filter := ex.server.cfg.TestingKnobs.StatementFilter; retErr == nil && filter != nil {
var execErr error
if perr, ok := retPayload.(payloadWithError); ok {
execErr = perr.errorCause()
}
filter(ctx, ex.sessionData(), ast.String(), execErr)
}
// Do the auto-commit, if necessary. In the extended protocol, the
// auto-commit happens when the Sync message is handled.
if retEv != nil || retErr != nil {
return
}
if canAutoCommit && !isExtendedProtocol {
retEv, retPayload = ex.handleAutoCommit(ctx, ast)
}
}(ctx)
switch s := ast.(type) {
case *tree.BeginTransaction:
// BEGIN is only allowed if we are in an implicit txn.
if os.ImplicitTxn.Get() {
// When executing the BEGIN, we also need to set any transaction modes
// that were specified on the BEGIN statement.
if _, err := ex.planner.SetTransaction(ctx, &tree.SetTransaction{Modes: s.Modes}); err != nil {
return makeErrEvent(err)
}
ex.sessionDataStack.PushTopClone()
return eventTxnUpgradeToExplicit{}, nil, nil
}
return makeErrEvent(errTransactionInProgress)
case *tree.CommitTransaction:
// CommitTransaction is executed fully here; there's no plan for it.
ev, payload := ex.commitSQLTransaction(ctx, ast, ex.commitSQLTransactionInternal)
return ev, payload, nil
case *tree.RollbackTransaction:
// RollbackTransaction is executed fully here; there's no plan for it.
ev, payload := ex.rollbackSQLTransaction(ctx, s)
return ev, payload, nil
case *tree.Savepoint:
return ex.execSavepointInOpenState(ctx, s, res)
case *tree.ReleaseSavepoint:
ev, payload := ex.execRelease(ctx, s, res)
return ev, payload, nil
case *tree.RollbackToSavepoint:
ev, payload := ex.execRollbackToSavepointInOpenState(ctx, s, res)
return ev, payload, nil
case *tree.Prepare:
// This is handling the SQL statement "PREPARE". See execPrepare for
// handling of the protocol-level command for preparing statements.
name := s.Name.String()
if _, ok := ex.extraTxnState.prepStmtsNamespace.prepStmts[name]; ok {
err := pgerror.Newf(
pgcode.DuplicatePreparedStatement,
"prepared statement %q already exists", name,
)
return makeErrEvent(err)
}
var typeHints tree.PlaceholderTypes
// We take max(len(s.Types), stmt.NumPlaceHolders) as the length of types.
numParams := len(s.Types)
if stmt.NumPlaceholders > numParams {
numParams = stmt.NumPlaceholders
}
if len(s.Types) > 0 {
typeHints = make(tree.PlaceholderTypes, numParams)
for i, t := range s.Types {
resolved, err := tree.ResolveType(ctx, t, ex.planner.semaCtx.GetTypeResolver())
if err != nil {
return makeErrEvent(err)
}
typeHints[i] = resolved
}
}
prepStmt := makeStatement(
parser.Statement{
// We need the SQL string just for the part that comes after
// "PREPARE ... AS",
// TODO(radu): it would be nice if the parser would figure out this
// string and store it in tree.Prepare.
SQL: tree.AsStringWithFlags(s.Statement, tree.FmtParsable),
AST: s.Statement,
NumPlaceholders: stmt.NumPlaceholders,
NumAnnotations: stmt.NumAnnotations,
},
ex.generateID(),
)
var rawTypeHints []oid.Oid
if _, err := ex.addPreparedStmt(
ctx, name, prepStmt, typeHints, rawTypeHints, PreparedStatementOriginSQL,
); err != nil {
return makeErrEvent(err)
}
return nil, nil, nil
}
p.semaCtx.Annotations = tree.MakeAnnotations(stmt.NumAnnotations)
// For regular statements (the ones that get to this point), we
// don't return any event unless an error happens.
if err := ex.handleAOST(ctx, ast); err != nil {
return makeErrEvent(err)
}
// The first order of business is to ensure proper sequencing
// semantics. As per PostgreSQL's dialect specs, the "read" part of
// statements always see the data as per a snapshot of the database
// taken the instant the statement begins to run. In particular a
// mutation does not see its own writes. If a query contains
// multiple mutations using CTEs (WITH) or a read part following a
// mutation, all still operate on the same read snapshot.
//
// (To communicate data between CTEs and a main query, the result
// set / RETURNING can be used instead. However this is not relevant
// here.)
// We first ensure stepping mode is enabled.
//
// This ought to be done just once when a txn gets initialized;
// unfortunately, there are too many places where the txn object
// is re-configured, re-set etc without using NewTxnWithSteppingEnabled().
//
// Manually hunting them down and calling ConfigureStepping() each
// time would be error prone (and increase the chance that a future
// change would forget to add the call).
//
// TODO(andrei): really the code should be rearchitected to ensure
// that all uses of SQL execution initialize the client.Txn using a
// single/common function. That would be where the stepping mode
// gets enabled once for all SQL statements executed "underneath".
prevSteppingMode := ex.state.mu.txn.ConfigureStepping(ctx, kv.SteppingEnabled)
defer func() { _ = ex.state.mu.txn.ConfigureStepping(ctx, prevSteppingMode) }()
// Then we create a sequencing point.
//
// This is not the only place where a sequencing point is
// placed. There are also sequencing point after every stage of
// constraint checks and cascading actions at the _end_ of a
// statement's execution.
//
// TODO(knz): At the time of this writing CockroachDB performs
// cascading actions and the corresponding FK existence checks
// interleaved with mutations. This is incorrect; the correct
// behavior, as described in issue
// https://github.com/cockroachdb/cockroach/issues/33475, is to
// execute cascading actions no earlier than after all the "main
// effects" of the current statement (including all its CTEs) have
// completed. There should be a sequence point between the end of
// the main execution and the start of the cascading actions, as
// well as in-between very stage of cascading actions.
// This TODO can be removed when the cascading code is reorganized
// accordingly and the missing call to Step() is introduced.
if err := ex.state.mu.txn.Step(ctx); err != nil {
return makeErrEvent(err)
}
if err := p.semaCtx.Placeholders.Assign(pinfo, stmt.NumPlaceholders); err != nil {
return makeErrEvent(err)
}
p.extendedEvalCtx.Placeholders = &p.semaCtx.Placeholders
p.extendedEvalCtx.Annotations = &p.semaCtx.Annotations
p.stmt = stmt
p.cancelChecker.Reset(ctx)
// Auto-commit is disallowed during statement execution if we previously
// executed any DDL. This is because may potentially create jobs and do other
// operations rather than a KV commit.
// This prevents commit during statement execution, but the conn_executor
// will still commit this transaction after this statement executes.
p.autoCommit = canAutoCommit &&
!ex.server.cfg.TestingKnobs.DisableAutoCommitDuringExec && ex.extraTxnState.numDDL == 0
p.extendedEvalCtx.TxnIsSingleStmt = canAutoCommit && !ex.extraTxnState.firstStmtExecuted
ex.extraTxnState.firstStmtExecuted = true
var stmtThresholdSpan *tracing.Span
alreadyRecording := ex.transitionCtx.sessionTracing.Enabled()
stmtTraceThreshold := TraceStmtThreshold.Get(&ex.planner.execCfg.Settings.SV)
var stmtCtx context.Context
// TODO(andrei): I think we should do this even if alreadyRecording == true.
if !alreadyRecording && stmtTraceThreshold > 0 {
stmtCtx, stmtThresholdSpan = tracing.EnsureChildSpan(ctx, ex.server.cfg.AmbientCtx.Tracer, "trace-stmt-threshold", tracing.WithRecording(tracingpb.RecordingVerbose))
} else {
stmtCtx = ctx
}
if err := ex.dispatchToExecutionEngine(stmtCtx, p, res); err != nil {
stmtThresholdSpan.Finish()
return nil, nil, err
}
if stmtThresholdSpan != nil {
stmtDur := timeutil.Since(ex.phaseTimes.GetSessionPhaseTime(sessionphase.SessionQueryReceived))
needRecording := stmtTraceThreshold < stmtDur
if needRecording {
rec := stmtThresholdSpan.FinishAndGetRecording(tracingpb.RecordingVerbose)
// NB: This recording does not include the commit for implicit
// transactions if the statement didn't auto-commit.
logTraceAboveThreshold(
ctx,
rec,
fmt.Sprintf("SQL stmt %s", stmt.AST.String()),
stmtTraceThreshold,
stmtDur,
)
} else {
stmtThresholdSpan.Finish()
}
}
if err := res.Err(); err != nil {
return makeErrEvent(err)
}
txn := ex.state.mu.txn
if !os.ImplicitTxn.Get() && txn.IsSerializablePushAndRefreshNotPossible() {
rc, canAutoRetry := ex.getRewindTxnCapability()
if canAutoRetry {
ev := eventRetriableErr{
IsCommit: fsm.FromBool(isCommit(ast)),
CanAutoRetry: fsm.FromBool(canAutoRetry),
}
payload := eventRetriableErrPayload{
err: txn.GenerateForcedRetryableError(ctx, "serializable transaction timestamp pushed (detected by connExecutor)"),
rewCap: rc,
}
return ev, payload, nil
}
log.VEventf(ctx, 2, "push detected for non-refreshable txn but auto-retry not possible")
}
// No event was generated.
return nil, nil, nil
}
// handleAOST gets the AsOfSystemTime clause from the statement, and sets
// the timestamps of the transaction accordingly.
func (ex *connExecutor) handleAOST(ctx context.Context, stmt tree.Statement) error {
if _, isNoTxn := ex.machine.CurState().(stateNoTxn); isNoTxn {
return errors.AssertionFailedf(
"cannot handle AOST clause without a transaction",
)
}
p := &ex.planner
asOf, err := p.isAsOf(ctx, stmt)
if err != nil {
return err
}
if asOf == nil {
return nil
}
// Implicit transactions can have multiple statements, so we need to check
// if one has already been executed.
if ex.implicitTxn() && !ex.extraTxnState.firstStmtExecuted {
if p.extendedEvalCtx.AsOfSystemTime == nil {
p.extendedEvalCtx.AsOfSystemTime = asOf
if !asOf.BoundedStaleness {
p.extendedEvalCtx.SetTxnTimestamp(asOf.Timestamp.GoTime())
if err := ex.state.setHistoricalTimestamp(ctx, asOf.Timestamp); err != nil {
return err
}
}
return nil
}
if *p.extendedEvalCtx.AsOfSystemTime == *asOf {
// In most cases, the AOST timestamps are expected to match.
return nil
}
if p.extendedEvalCtx.AsOfSystemTime.BoundedStaleness {
if !p.extendedEvalCtx.AsOfSystemTime.MaxTimestampBound.IsEmpty() {
// This has to be a bounded staleness read with nearest_only=True during
// a retry. The AOST read timestamps are expected to differ.
return nil
}
return errors.AssertionFailedf("expected bounded_staleness set with a max_timestamp_bound")
}
return pgerror.Newf(
pgcode.FeatureNotSupported,
"cannot specify AS OF SYSTEM TIME with different timestamps. expected: %s, got: %s",
p.extendedEvalCtx.AsOfSystemTime.Timestamp,
asOf.Timestamp,
)
}
// If we're in an explicit txn, we allow AOST but only if it matches with
// the transaction's timestamp. This is useful for running AOST statements
// using the InternalExecutor inside an external transaction; one might want
// to do that to force p.avoidLeasedDescriptors to be set below.
if asOf.BoundedStaleness {
return pgerror.Newf(
pgcode.FeatureNotSupported,
"cannot use a bounded staleness query in a transaction",
)
}
if readTs := ex.state.getReadTimestamp(); asOf.Timestamp != readTs {
err = pgerror.Newf(pgcode.FeatureNotSupported,
"inconsistent AS OF SYSTEM TIME timestamp; expected: %s, got: %s", readTs, asOf.Timestamp)
if !ex.implicitTxn() {
err = errors.WithHint(err, "try SET TRANSACTION AS OF SYSTEM TIME")
}
return err
}
p.extendedEvalCtx.AsOfSystemTime = asOf
return nil
}
func formatWithPlaceholders(ast tree.Statement, evalCtx *eval.Context) string {
var fmtCtx *tree.FmtCtx
fmtFlags := tree.FmtSimple
if evalCtx.HasPlaceholders() {
fmtCtx = evalCtx.FmtCtx(
fmtFlags,
tree.FmtPlaceholderFormat(func(ctx *tree.FmtCtx, placeholder *tree.Placeholder) {
d, err := eval.Expr(evalCtx, placeholder)
if err != nil || d == nil {
// Fall back to the default behavior if something goes wrong.
ctx.Printf("$%d", placeholder.Idx+1)
return
}
d.Format(ctx)
}),
)
} else {
fmtCtx = evalCtx.FmtCtx(fmtFlags)
}
fmtCtx.FormatNode(ast)
return fmtCtx.CloseAndGetString()
}
// checkDescriptorTwoVersionInvariant ensures that the two version invariant is
// upheld. It calls descs.CheckTwoVersionInvariant, which will restart the
// underlying transaction in the case that the invariant is not upheld, and
// it will cleanup any intents due to that transaction. When this happens, the
// transaction will be reset internally.
func (ex *connExecutor) checkDescriptorTwoVersionInvariant(ctx context.Context) error {
var inRetryBackoff func()
if knobs := ex.server.cfg.SchemaChangerTestingKnobs; knobs != nil {
inRetryBackoff = knobs.TwoVersionLeaseViolation
}
return descs.CheckTwoVersionInvariant(
ctx,
ex.server.cfg.Clock,
ex.server.cfg.InternalExecutor,
ex.extraTxnState.descCollection,
ex.state.mu.txn,
inRetryBackoff,
)
}
// Create a new transaction to retry with a higher timestamp than the timestamps
// used in any retry loop above. Additionally, make sure to copy out the
// priority from the previous transaction to ensure that livelock does not
// occur.
func (ex *connExecutor) resetTransactionOnSchemaChangeRetry(ctx context.Context) error {
ex.state.mu.Lock()
defer ex.state.mu.Unlock()
userPriority := ex.state.mu.txn.UserPriority()
ex.state.mu.txn = kv.NewTxnWithSteppingEnabled(ctx, ex.transitionCtx.db,
ex.transitionCtx.nodeIDOrZero, ex.QualityOfService())
return ex.state.mu.txn.SetUserPriority(userPriority)
}
// commitSQLTransaction executes a commit after the execution of a
// stmt, which can be any statement when executing a statement with an
// implicit transaction, or a COMMIT statement when using an explicit
// transaction. commitFn is passed as a separate function, so that we avoid
// executing transactional logic when handling COMMIT in the CommitWait state.
func (ex *connExecutor) commitSQLTransaction(
ctx context.Context, ast tree.Statement, commitFn func(context.Context) error,
) (fsm.Event, fsm.EventPayload) {
ex.phaseTimes.SetSessionPhaseTime(sessionphase.SessionStartTransactionCommit, timeutil.Now())
if err := commitFn(ctx); err != nil {
if descs.IsTwoVersionInvariantViolationError(err) {
if resetErr := ex.resetTransactionOnSchemaChangeRetry(ctx); resetErr != nil {
return ex.makeErrEvent(err, ast)
}
// Generating a forced retry error here, right after resetting the
// transaction is not exactly necessary, but it's a sound way to
// generate the only type of ClientVisibleRetryError we have.
err = ex.state.mu.txn.GenerateForcedRetryableError(ctx, err.Error())
}
return ex.makeErrEvent(err, ast)
}
ex.phaseTimes.SetSessionPhaseTime(sessionphase.SessionEndTransactionCommit, timeutil.Now())
if err := ex.reportSessionDataChanges(func() error {
ex.sessionDataStack.PopAll()
return nil
}); err != nil {
return ex.makeErrEvent(err, ast)
}
return eventTxnFinishCommitted{}, nil
}
// reportSessionDataChanges reports ParamStatusUpdate changes and re-calls
// and relevant session data callbacks after the given fn has been executed.
func (ex *connExecutor) reportSessionDataChanges(fn func() error) error {
before := ex.sessionDataStack.Top()
if err := fn(); err != nil {
return err
}
after := ex.sessionDataStack.Top()
if ex.dataMutatorIterator.paramStatusUpdater != nil {
for _, param := range bufferableParamStatusUpdates {
_, v, err := getSessionVar(param.lowerName, false /* missingOk */)
if err != nil {
return err
}
if v.Equal == nil {
return errors.AssertionFailedf("Equal for %s must be set", param.name)
}
if v.GetFromSessionData == nil {
return errors.AssertionFailedf("GetFromSessionData for %s must be set", param.name)
}
if !v.Equal(before, after) {
ex.dataMutatorIterator.paramStatusUpdater.BufferParamStatusUpdate(
param.name,
v.GetFromSessionData(after),
)
}
}
}
if before.DefaultIntSize != after.DefaultIntSize && ex.dataMutatorIterator.onDefaultIntSizeChange != nil {
ex.dataMutatorIterator.onDefaultIntSizeChange(after.DefaultIntSize)
}
if before.ApplicationName != after.ApplicationName && ex.dataMutatorIterator.onApplicationNameChange != nil {
ex.dataMutatorIterator.onApplicationNameChange(after.ApplicationName)
}
return nil
}
func (ex *connExecutor) commitSQLTransactionInternal(ctx context.Context) error {
ctx, sp := tracing.EnsureChildSpan(ctx, ex.server.cfg.AmbientCtx.Tracer, "commit sql txn")
defer sp.Finish()
if err := ex.extraTxnState.sqlCursors.closeAll(true /* errorOnWithHold */); err != nil {
return err
}
// We need to step the transaction before committing if it has stepping
// enabled. If it doesn't have stepping enabled, then we just set the
// stepping mode back to what it was.
prevSteppingMode := ex.state.mu.txn.ConfigureStepping(ctx, kv.SteppingEnabled)
if prevSteppingMode == kv.SteppingEnabled {
if err := ex.state.mu.txn.Step(ctx); err != nil {
return err
}
} else {
ex.state.mu.txn.ConfigureStepping(ctx, prevSteppingMode)
}
if err := ex.createJobs(ctx); err != nil {
return err
}
if ex.extraTxnState.schemaChangerState.mode != sessiondatapb.UseNewSchemaChangerOff {
if err := ex.runPreCommitStages(ctx); err != nil {
return err
}
}
zoneConfigValidator := newZoneConfigValidator(ex.state.mu.txn,
ex.extraTxnState.descCollection,
ex.planner.execCfg)
if err := ex.extraTxnState.descCollection.ValidateUncommittedDescriptors(ctx, ex.state.mu.txn, ex.extraTxnState.validateDbZoneConfig, zoneConfigValidator); err != nil {
return err
}
if err := descs.CheckSpanCountLimit(
ctx,
ex.extraTxnState.descCollection,
ex.server.cfg.SpanConfigSplitter,
ex.server.cfg.SpanConfigLimiter,
ex.state.mu.txn,
); err != nil {
return err
}
if err := ex.checkDescriptorTwoVersionInvariant(ctx); err != nil {
return err
}
if err := ex.state.mu.txn.Commit(ctx); err != nil {
return err
}
// Now that we've committed, if we modified any descriptor we need to make sure
// to release the leases for them so that the schema change can proceed and
// we don't block the client.
withNewVersion, err := ex.extraTxnState.descCollection.GetOriginalPreviousIDVersionsForUncommitted()