Add exporter for RocksDB context metrics (#931)

Signed-off-by: Vladimir Buyanov <b.vladimir@clickadu.com>

README.md

@@ -109,6 +109,7 @@ collect.info_schema.processlist                              | 5.1           | C
 collect.info_schema.processlist.min_time                     | 5.1           | Minimum time a thread must be in each state to be counted. (default: 0)
 collect.info_schema.query_response_time                      | 5.5           | Collect query response time distribution if query_response_time_stats is ON.
 collect.info_schema.replica_host                             | 5.6           | Collect metrics from information_schema.replica_host_status.
+collect.info_schema.rocksdb_perf_context                     | 5.6           | Collect RocksDB metrics from information_schema.ROCKSDB_PERF_CONTEXT.
 collect.info_schema.tables                                   | 5.1           | Collect metrics from information_schema.tables.
 collect.info_schema.tables.databases                         | 5.1           | The list of databases to collect table stats for, or '`*`' for all.
 collect.info_schema.tablestats                               | 5.1           | If running with userstat=1, set to true to collect table statistics.

collector/info_schema_rocksdb_perf_context.go

@@ -0,0 +1,273 @@
+// Copyright 2025 The Prometheus 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.
+
+// Scrape `information_schema.ROCKSDB_PERF_CONTEXT`.
+
+package collector
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const rocksdbPerfContextQuery = `
+                SELECT
+                  TABLE_SCHEMA, 
+                  TABLE_NAME, 
+                  ifnull(PARTITION_NAME, ''), 
+                  STAT_TYPE,
+                  VALUE
+                  FROM information_schema.ROCKSDB_PERF_CONTEXT
+                `
+
+// Metric descriptors.
+var informationSchemaRocksDBLabels = []string{"schema", "table", "part"}
+var informationSchemaRocksDBPerfContextMetrics = map[string]struct {
+	vtype prometheus.ValueType
+	desc  *prometheus.Desc
+}{
+	"USER_KEY_COMPARISON_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_user_key_comparison_count"),
+			"Total number of user key comparisons performed in binary search.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"BLOCK_CACHE_HIT_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_block_cache_hit_count"),
+			"Total number of block read operations from cache.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"BLOCK_READ_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_block_read_count"),
+			"Total number of block read operations from disk.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"BLOCK_READ_BYTE": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_block_read_byte"),
+			"Total number of bytes read from disk.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"GET_READ_BYTES": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_get_read_bytes"),
+			"Number of bytes read during Get operations.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"MULTIGET_READ_BYTES": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_multiget_read_bytes"),
+			"Number of bytes read during MultiGet operations.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"ITER_READ_BYTES": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_iter_read_bytes"),
+			"Number of bytes read during iterator operations.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"INTERNAL_KEY_SKIPPED_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_internal_key_skipped_count"),
+			"Count of internal keys skipped during operations.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"INTERNAL_DELETE_SKIPPED_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_internal_delete_skipped_count"),
+			"Count of internal delete operations that were skipped.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"INTERNAL_RECENT_SKIPPED_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_internal_recent_skipped_count"),
+			"Count of recently skipped internal operations.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"INTERNAL_MERGE_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_internal_merge_count"),
+			"Total number of internal merge operations.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"GET_FROM_MEMTABLE_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_get_from_memtable_count"),
+			"Number of Get operations served from the memtable.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"SEEK_ON_MEMTABLE_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_seek_on_memtable_count"),
+			"Count of seek operations in the memtable.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"NEXT_ON_MEMTABLE_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_next_on_memtable_count"),
+			"Count of next operations in the memtable.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"PREV_ON_MEMTABLE_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_prev_on_memtable_count"),
+			"Count of previous operations in the memtable.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"SEEK_CHILD_SEEK_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_seek_child_seek_count"),
+			"Count of child seek operations in RocksDB.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"BLOOM_MEMTABLE_HIT_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_bloom_memtable_hit_count"),
+			"Count of successful hits in the bloom filter for memtable searches.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"BLOOM_MEMTABLE_MISS_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_bloom_memtable_miss_count"),
+			"Count of misses in the bloom filter for memtable searches.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"BLOOM_SST_HIT_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_bloom_sst_hit_count"),
+			"Count of successful hits in the bloom filter for SSTable searches.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"BLOOM_SST_MISS_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_bloom_sst_miss_count"),
+			"Count of misses in the bloom filter for SSTable searches.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"KEY_LOCK_WAIT_COUNT": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_key_lock_wait_count"),
+			"Count of key lock wait events in RocksDB.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"IO_BYTES_WRITTEN": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_io_bytes_written"),
+			"Total number of bytes written by I/O operations in RocksDB.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+	"IO_BYTES_READ": {
+		prometheus.CounterValue,
+		prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, informationSchema, "rocksdb_perf_context_io_bytes_read"),
+			"Total number of bytes read by I/O operations in RocksDB.",
+			informationSchemaRocksDBLabels, nil,
+		),
+	},
+}
+
+// ScrapeInnodbCmp collects from `information_schema.innodb_cmp`.
+type ScrapeRocksDBPerfContext struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeRocksDBPerfContext) Name() string {
+	return informationSchema + ".rocksdb_perf_context"
+}
+
+// Help describes the role of the Scraper.
+func (ScrapeRocksDBPerfContext) Help() string {
+	return "Collect metrics from information_schema.ROCKSDB_PERF_CONTEXT"
+}
+
+// Version of MySQL from which scraper is available.
+func (ScrapeRocksDBPerfContext) Version() float64 {
+	return 5.6
+}
+
+// Scrape collects data from database connection and sends it over channel as prometheus metric.
+func (ScrapeRocksDBPerfContext) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger *slog.Logger) error {
+	db := instance.getDB()
+	informationSchemaInnodbCmpMemRows, err := db.QueryContext(ctx, rocksdbPerfContextQuery)
+	if err != nil {
+		return err
+	}
+	defer informationSchemaInnodbCmpMemRows.Close()
+
+	var (
+		schema, table, part, stat string
+		value                     float64
+	)
+
+	for informationSchemaInnodbCmpMemRows.Next() {
+		if err := informationSchemaInnodbCmpMemRows.Scan(
+			&schema, &table, &part, &stat, &value,
+		); err != nil {
+			return err
+		}
+		if v, ok := informationSchemaRocksDBPerfContextMetrics[stat]; ok {
+			ch <- prometheus.MustNewConstMetric(v.desc, v.vtype, value, schema, table, part)
+		}
+	}
+	return nil
+}
+
+// check interface
+var _ Scraper = ScrapeRocksDBPerfContext{}

mysqld_exporter.go

@@ -104,6 +104,7 @@ var scrapers = map[collector.Scraper]bool{
 	collector.ScrapeHeartbeat{}:                           false,
 	collector.ScrapeSlaveHosts{}:                          false,
 	collector.ScrapeReplicaHost{}:                         false,
+	collector.ScrapeRocksDBPerfContext{}:                  false,
 }
 
 func filterScrapers(scrapers []collector.Scraper, collectParams []string) []collector.Scraper {