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executor_statement_metrics.go
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/
executor_statement_metrics.go
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// Copyright 2017 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 (
"time"
"github.com/cockroachdb/cockroach/pkg/sql/parser"
"github.com/cockroachdb/cockroach/pkg/util/log"
)
// SQL execution is separated in 3+ phases:
// - parse/prepare
// - plan
// - run
//
// The commonly used term "execution latency" encompasses this entire
// process. However for the purpose of analyzing / optimizing
// individual parts of the SQL execution engine, it is useful to
// separate the durations of these individual phases. The code below
// does this.
// sessionPhase is used to index the Session.phaseTimes array.
type sessionPhase int
const (
// When the session is created (pgwire). Used to compute
// the session age.
sessionInit sessionPhase = iota
// When a batch of SQL code is received in pgwire.
// Used to compute the batch age.
sessionStartBatch
// Executor phases.
sessionStartParse
sessionEndParse
plannerStartLogicalPlan
plannerEndLogicalPlan
plannerStartExecStmt
plannerEndExecStmt
// sessionNumPhases must be listed last so that it can be used to
// define arrays sufficiently large to hold all the other values.
sessionNumPhases
)
// phaseTimes is the type of the session.phaseTimes array.
type phaseTimes [sessionNumPhases]time.Time
// recordStatementSummery gathers various details pertaining to the
// last executed statement/query and performs the associated
// accounting.
// - distSQLUsed reports whether the query was distributed.
// - automaticRetryCount is the count of implicit txn retries
// so far.
// - result is the result set computed by the query/statement.
// - err is the error encountered, if any.
func (e *Executor) recordStatementSummary(
planner *planner,
stmt Statement,
distSQLUsed bool,
automaticRetryCount int,
resultWriter StatementResult,
err error,
) {
phaseTimes := &planner.phaseTimes
// Compute the run latency. This is always recorded in the
// server metrics.
runLatRaw := phaseTimes[plannerEndExecStmt].Sub(phaseTimes[plannerStartExecStmt])
// Collect the statistics.
numRows := resultWriter.RowsAffected()
runLat := runLatRaw.Seconds()
parseLat := phaseTimes[sessionEndParse].
Sub(phaseTimes[sessionStartParse]).Seconds()
planLat := phaseTimes[plannerEndLogicalPlan].
Sub(phaseTimes[plannerStartLogicalPlan]).Seconds()
// service latency: start to parse to end of run
svcLatRaw := phaseTimes[plannerEndExecStmt].Sub(phaseTimes[sessionStartParse])
svcLat := svcLatRaw.Seconds()
// processing latency: contributing towards SQL results.
processingLat := parseLat + planLat + runLat
// overhead latency: txn/retry management, error checking, etc
execOverhead := svcLat - processingLat
if automaticRetryCount == 0 {
if distSQLUsed {
if _, ok := stmt.AST.(*parser.Select); ok {
e.DistSQLSelectCount.Inc(1)
}
e.DistSQLExecLatency.RecordValue(runLatRaw.Nanoseconds())
e.DistSQLServiceLatency.RecordValue(svcLatRaw.Nanoseconds())
} else {
e.SQLExecLatency.RecordValue(runLatRaw.Nanoseconds())
e.SQLServiceLatency.RecordValue(svcLatRaw.Nanoseconds())
}
}
planner.session.appStats.recordStatement(
stmt, distSQLUsed, automaticRetryCount, numRows, err,
parseLat, planLat, runLat, svcLat, execOverhead,
)
if log.V(2) {
// ages since significant epochs
batchAge := phaseTimes[plannerEndExecStmt].
Sub(phaseTimes[sessionStartBatch]).Seconds()
sessionAge := phaseTimes[plannerEndExecStmt].
Sub(phaseTimes[sessionInit]).Seconds()
log.Infof(planner.session.Ctx(),
"query stats: %d rows, %d retries, "+
"parse %.2fµs (%.1f%%), "+
"plan %.2fµs (%.1f%%), "+
"run %.2fµs (%.1f%%), "+
"overhead %.2fµs (%.1f%%), "+
"batch age %.3fms, session age %.4fs",
numRows, automaticRetryCount,
parseLat*1e6, 100*parseLat/svcLat,
planLat*1e6, 100*planLat/svcLat,
runLat*1e6, 100*runLat/svcLat,
execOverhead*1e6, 100*execOverhead/svcLat,
batchAge*1000, sessionAge,
)
}
}