[WIP] Use UNLOGGED TABLES on PostgreSQL

backends/sqldb.go

@@ -15,12 +15,18 @@ const (
 	dbTypeMysql    = "mysql"
 )
 
+// Opt represents SQL DB backend's options.
+type Opt struct {
+	DBType         string
+	ResultsTable   string
+	UnloggedTables bool
+}
+
 // sqlDB represents the sqlDB backend.
 type sqlDB struct {
-	db           *sql.DB
-	dbType       string
-	resultsTable string
-	logger       *log.Logger
+	db     *sql.DB
+	opt    Opt
+	logger *log.Logger
 
 	// The result schemas (CREATE TABLE ...) are dynamically
 	// generated everytime queries are executed based on their result columns.
@@ -53,22 +59,22 @@ type insertSchema struct {
 
 // NewSQLBackend returns a new sqlDB result backend instance.
 // It accepts an *sql.DB connection
-func NewSQLBackend(db *sql.DB, dbType string, resTable string, l *log.Logger) (ResultBackend, error) {
+func NewSQLBackend(db *sql.DB, opt Opt, l *log.Logger) (ResultBackend, error) {
 	var (
 		r = sqlDB{
 			db:              db,
-			dbType:          dbType,
+			opt:             opt,
 			resTableSchemas: make(map[string]insertSchema),
 			schemaMutex:     sync.RWMutex{},
 			logger:          l,
 		}
 	)
 
 	// Config.
-	if resTable != "" {
-		r.resultsTable = resTable
+	if opt.ResultsTable != "" {
+		r.opt.ResultsTable = opt.ResultsTable
 	} else {
-		r.resultsTable = "results_%s"
+		r.opt.ResultsTable = "results_%s"
 	}
 
 	return &r, nil
@@ -87,7 +93,7 @@ func (s *sqlDB) NewResultSet(jobID, taskName string, ttl time.Duration) (ResultS
 		jobID:    jobID,
 		taskName: taskName,
 		backend:  s,
-		tbl:      fmt.Sprintf(s.resultsTable, jobID),
+		tbl:      fmt.Sprintf(s.opt.ResultsTable, jobID),
 		tx:       tx,
 	}, nil
 }
@@ -115,7 +121,7 @@ func (w *sqlDBWriter) RegisterColTypes(cols []string, colTypes []*sql.ColumnType
 		colNameHolder[i] = fmt.Sprintf(`"%s"`, w.cols[i])
 
 		// This will be filled by the driver.
-		if w.backend.dbType == dbTypePostgres {
+		if w.backend.opt.DBType == dbTypePostgres {
 			// Postgres placeholders are $1, $2 ...
 			colValHolder[i] = fmt.Sprintf("$%d", i+1)
 		} else {
@@ -223,11 +229,12 @@ func (s *sqlDB) createTableSchema(cols []string, colTypes []*sql.ColumnType) ins
 		colNameHolder = make([]string, len(cols))
 		colValHolder  = make([]string, len(cols))
 	)
+
 	for i := range cols {
 		colNameHolder[i] = fmt.Sprintf(`"%s"`, cols[i])
 
 		// This will be filled by the driver.
-		if s.dbType == dbTypePostgres {
+		if s.opt.DBType == dbTypePostgres {
 			// Postgres placeholders are $1, $2 ...
 			colValHolder[i] = fmt.Sprintf("$%d", i+1)
 		} else {
@@ -236,9 +243,11 @@ func (s *sqlDB) createTableSchema(cols []string, colTypes []*sql.ColumnType) ins
 	}
 
 	var (
-		fields = make([]string, len(cols))
-		typ    = ""
+		fields   = make([]string, len(cols))
+		typ      = ""
+		unlogged = ""
 	)
+
 	for i := 0; i < len(cols); i++ {
 		typ = colTypes[i].DatabaseTypeName()
 		switch colTypes[i].DatabaseTypeName() {
@@ -256,7 +265,7 @@ func (s *sqlDB) createTableSchema(cols []string, colTypes []*sql.ColumnType) ins
 		case "BOOLEAN": // Postgres, MySQL
 			typ = "BOOLEAN"
 		case "JSON", "JSONB": // Postgres
-			if s.dbType != dbTypePostgres {
+			if s.opt.DBType != dbTypePostgres {
 				typ = "TEXT"
 			}
 		// _INT4, _INT8, _TEXT represent array types in Postgres
@@ -277,9 +286,16 @@ func (s *sqlDB) createTableSchema(cols []string, colTypes []*sql.ColumnType) ins
 		fields[i] = fmt.Sprintf(`"%s" %s`, cols[i], typ)
 	}
 
+	// If the DB is Postgres, optionally create an "unlogged" table that disables
+	// WAL, improving performance of throw-away cache tables.
+	// https://www.postgresql.org/docs/9.1/sql-createtable.html
+	if s.opt.DBType == dbTypePostgres && s.opt.UnloggedTables {
+		unlogged = "UNLOGGED"
+	}
+
 	return insertSchema{
 		dropTable:   `DROP TABLE IF EXISTS "%s";`,
-		createTable: fmt.Sprintf(`CREATE TABLE IF NOT EXISTS "%%s" (%s);`, strings.Join(fields, ",")),
+		createTable: fmt.Sprintf(`CREATE %s TABLE IF NOT EXISTS "%%s" (%s);`, unlogged, strings.Join(fields, ",")),
 		insertRow: fmt.Sprintf(`INSERT INTO "%%s" (%s) VALUES (%s)`, strings.Join(colNameHolder, ","),
 			strings.Join(colValHolder, ",")),
 	}

cmd/jobber_test.go

@@ -108,11 +108,16 @@ func setup() {
 		// retain result db to perform queries on this db
 		testResultDB = conn
 
+		var (
+			opt = backends.Opt{
+				DBType:         cfg.Type,
+				ResultsTable:   ko.String(fmt.Sprintf("results.%s.results_table", dbName)),
+				UnloggedTables: cfg.Unlogged,
+			}
+		)
+
 		// Create a new backend instance.
-		backend, err := backends.NewSQLBackend(conn,
-			cfg.Type,
-			ko.String(fmt.Sprintf("results.%s.results_table", dbName)),
-			sysLog)
+		backend, err := backends.NewSQLBackend(conn, opt, sysLog)
 		if err != nil {
 			sysLog.Fatalf("error initializing result backend: %v", err)
 		}

cmd/main.go

@@ -55,6 +55,7 @@ type Jobber struct {
 type DBConfig struct {
 	Type           string        `mapstructure:"type"`
 	DSN            string        `mapstructure:"dsn"`
+	Unlogged       bool          `mapstructure:"unlogged"`
 	MaxIdleConns   int           `mapstructure:"max_idle"`
 	MaxActiveConns int           `mapstructure:"max_active"`
 	ConnectTimeout time.Duration `mapstructure:"connect_timeout"`
@@ -163,11 +164,14 @@ func main() {
 			log.Fatal(err)
 		}
 
+		opt := backends.Opt{
+			DBType:         cfg.Type,
+			ResultsTable:   ko.String(fmt.Sprintf("results.%s.results_table", dbName)),
+			UnloggedTables: cfg.Unlogged,
+		}
+
 		// Create a new backend instance.
-		backend, err := backends.NewSQLBackend(conn,
-			cfg.Type,
-			ko.String(fmt.Sprintf("results.%s.results_table", dbName)),
-			sysLog)
+		backend, err := backends.NewSQLBackend(conn, opt, sysLog)
 		if err != nil {
 			log.Fatalf("error initializing result backend: %v", err)
 		}

config.toml.sample

@@ -15,6 +15,7 @@ state_address = "redis://127.0.0.1:6379/1"
 # Each job can specify where its results should be stored.
 # If there are multiple backends and jobs don't specify
 # a particular backend, the results will be saved to a *random* one.
+# The optional `unlogged = true` (for postgres) creates faster, unlogged (WAL) tables.
 #
 # type = "postgres" dsn = "postgres://user:password@host:5432/dbname?sslmode=disable"
 # type = "mysql" dsn = "user:password@tcp(host:3306)/dbname"