PMM-15161 False auto increment.

collector/info_schema_auto_increment.go

@@ -31,7 +31,7 @@ const infoSchemaAutoIncrementQuery = `
 		    when 'mediumint' then 23
 		    when 'int'       then 31
 		    when 'bigint'    then 63
-		    end+(column_type like '% unsigned'))-1 as max_int
+		    end+(column_type like '%unsigned%'))-1 as max_int
 		  FROM information_schema.columns c
 		  STRAIGHT_JOIN information_schema.tables t ON (BINARY c.table_schema=t.table_schema AND BINARY c.table_name=t.table_name)
 		  WHERE c.extra = 'auto_increment' AND t.auto_increment IS NOT NULL

collector/info_schema_auto_increment_live_test.go

@@ -0,0 +1,116 @@
+// Copyright 2018 The Prometheus Authors, 2026 Percona LLC
+// 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 collector
+
+import (
+	"database/sql"
+	"fmt"
+	"math"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/promslog"
+)
+
+// TestScrapeAutoIncrementColumnsMaxValue evaluates the max_int expression on the
+// server started by docker-compose, so every flavor of the CI matrix checks it.
+// ZEROFILL appends another attribute after "unsigned" in column_type, which an
+// anchored LIKE '% unsigned' misses: such columns reported the signed maximum
+// and so looked twice as full as they were.
+func TestScrapeAutoIncrementColumnsMaxValue(t *testing.T) {
+	if testing.Short() {
+		t.Skip("-short is passed, skipping test")
+	}
+
+	db, err := sql.Open("mysql", "root@tcp(127.0.0.1:3306)/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	const dbName = "test_auto_increment_db"
+
+	if _, err := db.Exec("CREATE DATABASE IF NOT EXISTS " + dbName); err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		if _, err := db.Exec("DROP DATABASE " + dbName); err != nil {
+			t.Fatal(err)
+		}
+	}()
+
+	cases := []struct {
+		name    string
+		column  string
+		wantMax float64
+	}{
+		{"signed_int", "int not null auto_increment", math.Pow(2, 31) - 1},
+		{"unsigned_int", "int unsigned not null auto_increment", math.Pow(2, 32) - 1},
+		{"zerofill_int", "int unsigned zerofill not null auto_increment", math.Pow(2, 32) - 1},
+		{"unsigned_smallint", "smallint unsigned not null auto_increment", math.Pow(2, 16) - 1},
+		{"unsigned_bigint", "bigint unsigned not null auto_increment", math.Pow(2, 64) - 1},
+	}
+
+	ctx := t.Context()
+
+	for _, c := range cases {
+		if _, err := db.ExecContext(ctx, fmt.Sprintf("CREATE TABLE %s.%s (id %s, PRIMARY KEY (id))", dbName, c.name, c.column)); err != nil {
+			t.Fatalf("creating table %s: %v", c.name, err)
+		}
+
+		// The scraper skips tables whose information_schema.tables.auto_increment
+		// is NULL, which is what a never-used counter reports. ANALYZE TABLE then
+		// refreshes the value the dictionary cache would otherwise serve for
+		// information_schema_stats_expiry seconds.
+		if _, err := db.ExecContext(ctx, fmt.Sprintf("INSERT INTO %s.%s () VALUES ()", dbName, c.name)); err != nil {
+			t.Fatalf("seeding table %s: %v", c.name, err)
+		}
+		if _, err := db.ExecContext(ctx, fmt.Sprintf("ANALYZE TABLE %s.%s", dbName, c.name)); err != nil {
+			t.Fatalf("analyzing table %s: %v", c.name, err)
+		}
+	}
+
+	ch := make(chan prometheus.Metric)
+	scrapeErr := make(chan error, 1)
+	go func() {
+		scrapeErr <- (ScrapeAutoIncrementColumns{}).Scrape(ctx, &instance{db: db}, ch, promslog.NewNopLogger())
+		close(ch)
+	}()
+
+	got := make(map[string]float64)
+	for metric := range ch {
+		if metric.Desc() != globalInfoSchemaAutoIncrementMaxDesc {
+			continue
+		}
+		result := readMetric(metric)
+		if result.labels["schema"] != dbName {
+			continue
+		}
+		got[result.labels["table"]] = result.value
+	}
+	if err := <-scrapeErr; err != nil {
+		t.Fatalf("scrape failed: %v", err)
+	}
+
+	for _, c := range cases {
+		gotMax, ok := got[c.name]
+		if !ok {
+			t.Errorf("no max metric for table %s; collected: %v", c.name, got)
+			continue
+		}
+		if gotMax != c.wantMax {
+			t.Errorf("table %s (%s): max = %.0f, want %.0f", c.name, c.column, gotMax, c.wantMax)
+		}
+	}
+}

collector/info_schema_auto_increment_test.go

@@ -0,0 +1,77 @@
+// Copyright 2018 The Prometheus Authors, 2026 Percona LLC
+// 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 collector
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/common/promslog"
+)
+
+// The mock returns max_int verbatim, so this only covers turning rows into
+// metrics. The unsigned detection lives in the SQL itself and is covered by
+// TestScrapeAutoIncrementColumnsMaxValue against a real server.
+func TestScrapeAutoIncrementColumns(t *testing.T) {
+	db, mock, err := sqlmock.New(sqlmock.QueryMatcherOption(sqlmock.QueryMatcherEqual))
+	if err != nil {
+		t.Fatalf("error opening a stub database connection: %s", err)
+	}
+	defer db.Close()
+
+	rows := sqlmock.NewRows([]string{"table_schema", "table_name", "column_name", "auto_increment", "max_int"}).
+		AddRow("test", "signed", "id", 20_000, 32_767).
+		AddRow("test", "unsigned", "id", 47_000, 65_535)
+	mock.ExpectQuery(infoSchemaAutoIncrementQuery).WillReturnRows(rows)
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		if err := (ScrapeAutoIncrementColumns{}).Scrape(
+			context.Background(),
+			&instance{db: db},
+			ch,
+			promslog.NewNopLogger(),
+		); err != nil {
+			t.Errorf("error calling function on test: %s", err)
+		}
+		close(ch)
+	}()
+
+	expected := []MetricResult{
+		{labels: labelMap{"schema": "test", "table": "signed", "column": "id"}, value: 20_000, metricType: dto.MetricType_GAUGE},
+		{labels: labelMap{"schema": "test", "table": "signed", "column": "id"}, value: 32_767, metricType: dto.MetricType_GAUGE},
+		{labels: labelMap{"schema": "test", "table": "unsigned", "column": "id"}, value: 47_000, metricType: dto.MetricType_GAUGE},
+		{labels: labelMap{"schema": "test", "table": "unsigned", "column": "id"}, value: 65_535, metricType: dto.MetricType_GAUGE},
+	}
+	for i, want := range expected {
+		metric, ok := <-ch
+		if !ok {
+			t.Fatalf("channel closed after %d metrics, want %d", i, len(expected))
+		}
+		if got := readMetric(metric); !reflect.DeepEqual(got, want) {
+			t.Errorf("metric %d mismatch:\ngot  %#v\nwant %#v", i, got, want)
+		}
+	}
+	if extra, ok := <-ch; ok {
+		t.Errorf("unexpected extra metric: %#v", readMetric(extra))
+	}
+
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Fatalf("unmet SQL expectations: %s", err)
+	}
+}