server: add http api to get some info of sub-optimal query #10717
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| Original file line number | Diff line number | Diff line change |
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| // Copyright 2019 PingCAP, Inc. | ||
| // | ||
| // 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, | ||
| // See the License for the specific language governing permissions and | ||
| // limitations under the License. | ||
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| package server | ||
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| import ( | ||
| "archive/zip" | ||
| "context" | ||
| "encoding/json" | ||
| "fmt" | ||
| "net/http" | ||
| "runtime/pprof" | ||
| "strconv" | ||
| "strings" | ||
| "time" | ||
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| "github.com/pingcap/parser" | ||
| "github.com/pingcap/parser/ast" | ||
| "github.com/pingcap/parser/model" | ||
| "github.com/pingcap/parser/terror" | ||
| "github.com/pingcap/tidb/domain" | ||
| "github.com/pingcap/tidb/session" | ||
| "github.com/pingcap/tidb/statistics/handle" | ||
| "github.com/pingcap/tidb/util/sqlexec" | ||
| "github.com/pingcap/tidb/util/testkit" | ||
| ) | ||
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| type sqlInfoFetcher struct { | ||
| do *domain.Domain | ||
| s session.Session | ||
| } | ||
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| type tableNamePair struct { | ||
| DBName string | ||
| TableName string | ||
| } | ||
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| type tableNameExtractor struct { | ||
| names map[tableNamePair]struct{} | ||
| } | ||
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| func (tne *tableNameExtractor) Enter(in ast.Node) (ast.Node, bool) { | ||
| if _, ok := in.(*ast.TableName); ok { | ||
| return in, true | ||
| } | ||
| return in, false | ||
| } | ||
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| func (tne *tableNameExtractor) Leave(in ast.Node) (ast.Node, bool) { | ||
| if t, ok := in.(*ast.TableName); ok { | ||
| tp := tableNamePair{DBName: t.Schema.L, TableName: t.Name.L} | ||
| if _, ok := tne.names[tp]; !ok { | ||
| tne.names[tp] = struct{}{} | ||
| } | ||
| } | ||
| return in, true | ||
| } | ||
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| func (sh *sqlInfoFetcher) zipInfoForSQL(w http.ResponseWriter, r *http.Request) { | ||
| reqCtx := r.Context() | ||
| sql := r.FormValue("sql") | ||
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| pprofTimeString := r.FormValue("pprof_time") | ||
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| timeoutString := r.FormValue("timeout") | ||
| var ( | ||
| pprofTime int | ||
| timeout int | ||
| err error | ||
| ) | ||
| if pprofTimeString != "" { | ||
| pprofTime, err = strconv.Atoi(pprofTimeString) | ||
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| } | ||
| if err != nil { | ||
|
There was a problem hiding this comment. check |
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| serveError(w, http.StatusBadRequest, "invalid value for pprof_time") | ||
| return | ||
| } | ||
| if pprofTime < 5 { | ||
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| serveError(w, http.StatusBadRequest, "pprof time is too short") | ||
|
There was a problem hiding this comment. I think a best practice for this kind of error message is:
There was a problem hiding this comment. Should we return here if it's an invalid value? |
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| } | ||
| if timeoutString != "" { | ||
| timeout, err = strconv.Atoi(timeoutString) | ||
| } | ||
| if err != nil { | ||
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| serveError(w, http.StatusBadRequest, "invalid value for timeout") | ||
| return | ||
| } | ||
| if timeout < pprofTime { | ||
| timeout = pprofTime | ||
| } | ||
| pairs, err := sh.extractTableNames(sql) | ||
| if err != nil { | ||
| serveError(w, http.StatusBadRequest, fmt.Sprintf("invalid SQL text, err: %v", err)) | ||
|
There was a problem hiding this comment. how about "failed to extract table names, sql: %v" There was a problem hiding this comment. But the sql is something given by the user. |
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| return | ||
| } | ||
| zw := zip.NewWriter(w) | ||
| defer func() { | ||
| terror.Log(zw.Close()) | ||
| }() | ||
| for pair := range pairs { | ||
| jsonTbl, err := sh.getStatsForTable(pair) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| continue | ||
|
There was a problem hiding this comment. Should we continue or just throw error out? There was a problem hiding this comment. can we return a message to indicate the failure of dumping stats for this table? There was a problem hiding this comment. write a file like |
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| } | ||
| statsFw, err := zw.Create(fmt.Sprintf("%v.%v.json", pair.DBName, pair.TableName)) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| continue | ||
| } | ||
| data, err := json.Marshal(jsonTbl) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| continue | ||
| } | ||
| _, err = statsFw.Write(data) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| continue | ||
| } | ||
| } | ||
| for pair := range pairs { | ||
| err = sh.getShowCreateTable(pair, zw) | ||
| if err != nil { | ||
| serveError(w, http.StatusInternalServerError, fmt.Sprintf("get schema for %v.%v failed", pair.DBName, pair.TableName)) | ||
|
There was a problem hiding this comment. Is it ok that we write error messages and zip formatted data to There was a problem hiding this comment. In fact, it's not very ok. The following is the curl result when error arisen. But the api There was a problem hiding this comment. OK... for simplifying, we can leave it as a further optimization and do it in another PR and please add a TODO here. |
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| return | ||
| } | ||
| } | ||
| // If we don't catch profile. We just get a explain result. | ||
| if pprofTime == 0 { | ||
| recordSets, err := sh.s.(sqlexec.SQLExecutor).Execute(reqCtx, fmt.Sprintf("explain %s", sql)) | ||
| if len(recordSets) > 0 { | ||
| defer terror.Call(recordSets[0].Close) | ||
| } | ||
| if err != nil { | ||
| serveError(w, http.StatusInternalServerError, fmt.Sprintf("execute SQL failed, err: %v", err)) | ||
| return | ||
| } | ||
| sRows, err := testkit.ResultSetToStringSlice(reqCtx, sh.s, recordSets[0]) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| return | ||
| } | ||
| fw, err := zw.Create("explain.result") | ||
| if err != nil { | ||
| terror.Log(err) | ||
| return | ||
| } | ||
| for _, row := range sRows { | ||
| fmt.Fprintf(fw, "%s\n", strings.Join(row, "\t")) | ||
| } | ||
| } else { | ||
| // Otherwise we catch a profile and run `EXPLAIN ANALYZE` result. | ||
| ctx, cancelFunc := context.WithCancel(reqCtx) | ||
| timer := time.NewTimer(time.Second * time.Duration(timeout)) | ||
| resultChan := make(chan *explainAnalyzeResult) | ||
| go sh.getExplainAnalyze(ctx, sql, resultChan) | ||
| errChan := make(chan error) | ||
| go sh.catchCPUProfile(reqCtx, pprofTime, zw, errChan) | ||
| select { | ||
| case result := <-resultChan: | ||
| timer.Stop() | ||
| cancelFunc() | ||
| if result.err != nil { | ||
| serveError(w, http.StatusInternalServerError, fmt.Sprintf("explain analyze SQL failed, err: %v", err)) | ||
| return | ||
| } | ||
| if len(result.rows) == 0 { | ||
| break | ||
| } | ||
| fw, err := zw.Create("explain_analyze.result") | ||
| if err != nil { | ||
| terror.Log(err) | ||
| break | ||
| } | ||
| for _, row := range result.rows { | ||
| fmt.Fprintf(fw, "%s\n", strings.Join(row, "\t")) | ||
| } | ||
| case <-timer.C: | ||
| cancelFunc() | ||
| } | ||
| err = <-errChan | ||
| if err != nil { | ||
| serveError(w, http.StatusInternalServerError, fmt.Sprintf("catch cpu profile failed, error: %v", err)) | ||
| return | ||
| } | ||
| } | ||
| } | ||
|
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| type explainAnalyzeResult struct { | ||
| rows [][]string | ||
| err error | ||
| } | ||
|
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| func (sh *sqlInfoFetcher) getExplainAnalyze(ctx context.Context, sql string, resultChan chan<- *explainAnalyzeResult) { | ||
| recordSets, err := sh.s.(sqlexec.SQLExecutor).Execute(ctx, fmt.Sprintf("explain analyze %s", sql)) | ||
| if len(recordSets) > 0 { | ||
| defer terror.Call(recordSets[0].Close) | ||
| } | ||
| if err != nil { | ||
| resultChan <- &explainAnalyzeResult{err: err} | ||
| return | ||
| } | ||
| rows, err := testkit.ResultSetToStringSlice(ctx, sh.s, recordSets[0]) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| rows = nil | ||
| return | ||
| } | ||
| resultChan <- &explainAnalyzeResult{rows: rows} | ||
| } | ||
|
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| func (sh *sqlInfoFetcher) catchCPUProfile(ctx context.Context, sec int, zw *zip.Writer, errChan chan<- error) { | ||
| // dump profile | ||
| fw, err := zw.Create("profile") | ||
| if err != nil { | ||
| errChan <- err | ||
| return | ||
| } | ||
| if err := pprof.StartCPUProfile(fw); err != nil { | ||
| errChan <- err | ||
| return | ||
| } | ||
| sleepWithCtx(ctx, time.Duration(sec)*time.Second) | ||
| pprof.StopCPUProfile() | ||
| errChan <- nil | ||
| } | ||
|
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| func (sh *sqlInfoFetcher) getStatsForTable(pair tableNamePair) (*handle.JSONTable, error) { | ||
| is := sh.do.InfoSchema() | ||
| h := sh.do.StatsHandle() | ||
| tbl, err := is.TableByName(model.NewCIStr(pair.DBName), model.NewCIStr(pair.TableName)) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| js, err := h.DumpStatsToJSON(pair.DBName, tbl.Meta(), nil) | ||
| return js, err | ||
| } | ||
|
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| func (sh *sqlInfoFetcher) getShowCreateTable(pair tableNamePair, zw *zip.Writer) error { | ||
| recordSets, err := sh.s.(sqlexec.SQLExecutor).Execute(context.TODO(), fmt.Sprintf("show create table `%v`.`%v`", pair.DBName, pair.TableName)) | ||
| if len(recordSets) > 0 { | ||
| defer terror.Call(recordSets[0].Close) | ||
| } | ||
| if err != nil { | ||
| return err | ||
| } | ||
| sRows, err := testkit.ResultSetToStringSlice(context.Background(), sh.s, recordSets[0]) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| return nil | ||
| } | ||
| fw, err := zw.Create(fmt.Sprintf("%v.%v.schema.txt", pair.DBName, pair.TableName)) | ||
| if err != nil { | ||
| terror.Log(err) | ||
| return nil | ||
| } | ||
| for _, row := range sRows { | ||
| fmt.Fprintf(fw, "%s\n", strings.Join(row, "\t")) | ||
| } | ||
| return nil | ||
| } | ||
|
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| func (sh *sqlInfoFetcher) extractTableNames(sql string) (map[tableNamePair]struct{}, error) { | ||
| p := parser.New() | ||
| charset, collation := sh.s.GetSessionVars().GetCharsetInfo() | ||
| stmts, _, err := p.Parse(sql, charset, collation) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| extractor := &tableNameExtractor{ | ||
| names: make(map[tableNamePair]struct{}), | ||
| } | ||
| for _, stmt := range stmts { | ||
|
There was a problem hiding this comment. So we allow multiple statements? Will it cause problems if we use |
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| stmt.Accept(extractor) | ||
| } | ||
| return extractor.names, nil | ||
| } | ||
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