[receiver/postgresql] Add Index Metrics (#13168)

Add index metrics

receiver/postgresqlreceiver/client.go

@@ -35,13 +35,17 @@ type databaseName string
 // i.e. database1|table2
 type tableIdentifier string
 
+// indexIdentifier is a unique string that identifies a particular index and is separated by the "|" character
+type indexIdentifer string
+
 type client interface {
  Close() error
  getDatabaseStats(ctx context.Context, databases []string) (map[databaseName]databaseStats, error)
  getBackends(ctx context.Context, databases []string) (map[databaseName]int64, error)
  getDatabaseSize(ctx context.Context, databases []string) (map[databaseName]int64, error)
  getDatabaseTableMetrics(ctx context.Context, db string) (map[tableIdentifier]tableStats, error)
  getBlocksReadByTable(ctx context.Context, db string) (map[tableIdentifier]tableIOStats, error)
+ getIndexStats(ctx context.Context, database string) (map[indexIdentifer]indexStat, error)
  listDatabases(ctx context.Context) ([]string, error)
 }
 
@@ -307,6 +311,50 @@ func (c *postgreSQLClient) getBlocksReadByTable(ctx context.Context, db string)
  return tios, errors
 }
 
+type indexStat struct {
+ index string
+ table string
+ database string
+ size int64
+ scans int64
+}
+
+func (c *postgreSQLClient) getIndexStats(ctx context.Context, database string) (map[indexIdentifer]indexStat, error) {
+ query := `SELECT relname, indexrelname,
+ pg_relation_size(indexrelid) AS index_size,
+ idx_scan
+ FROM pg_stat_user_indexes;`
+
+ stats := map[indexIdentifer]indexStat{}
+
+ rows, err := c.client.QueryContext(ctx, query)
+ if err != nil {
+ return nil, err
+ }
+ defer rows.Close()
+
+ var errs []error
+ for rows.Next() {
+ var (
+ table, index string
+ indexSize, indexScans int64
+ )
+ err := rows.Scan(&table, &index, &indexSize, &indexScans)
+ if err != nil {
+ errs = append(errs, err)
+ continue
+ }
+ stats[indexKey(database, table, index)] = indexStat{
+ index: index,
+ table: table,
+ database: database,
+ size: indexSize,
+ scans: indexScans,
+ }
+ }
+ return stats, multierr.Combine(errs...)
+}
+
 func (c *postgreSQLClient) listDatabases(ctx context.Context) ([]string, error) {
  query := `SELECT datname FROM pg_database
  WHERE datistemplate = false;`
@@ -350,3 +398,7 @@ func filterQueryByDatabases(baseQuery string, databases []string, groupBy bool)
 func tableKey(database, table string) tableIdentifier {
  return tableIdentifier(fmt.Sprintf("%s|%s", database, table))
 }
+
+func indexKey(database, table, index string) indexIdentifer {
+ return indexIdentifer(fmt.Sprintf("%s|%s|%s", database, table, index))
+}

receiver/postgresqlreceiver/documentation.md

@@ -12,6 +12,8 @@ These are the metrics available for this scraper.
 | **postgresql.blocks_read** | The number of blocks read. | 1 | Sum(Int) | <ul> <li>database</li> <li>table</li> <li>source</li> </ul> |
 | **postgresql.commits** | The number of commits. | 1 | Sum(Int) | <ul> <li>database</li> </ul> |
 | **postgresql.db_size** | The database disk usage. | By | Sum(Int) | <ul> <li>database</li> </ul> |
+| **postgresql.index.scans** | The number of index scans on a table. | {scans} | Sum(Int) | <ul> </ul> |
+| **postgresql.index.size** | The size of the index on disk. | By | Gauge(Int) | <ul> </ul> |
 | **postgresql.operations** | The number of db row operations. | 1 | Sum(Int) | <ul> <li>database</li> <li>table</li> <li>operation</li> </ul> |
 | **postgresql.rollbacks** | The number of rollbacks. | 1 | Sum(Int) | <ul> <li>database</li> </ul> |
 | **postgresql.rows** | The number of rows in the database. | 1 | Sum(Int) | <ul> <li>database</li> <li>table</li> <li>state</li> </ul> |
@@ -30,6 +32,7 @@ metrics:
 | Name | Description | Type |
 | ---- | ----------- | ---- |
 | postgresql.database.name | The name of the database. | String |
+| postgresql.index.name | The name of the index on a table. | String |
 | postgresql.table.name | The schema name followed by the table name. | String |
 
 ## Metric attributes

receiver/postgresqlreceiver/metadata.yaml

@@ -7,6 +7,9 @@ resource_attributes:
  postgresql.table.name:
  description: The schema name followed by the table name.
  type: string
+ postgresql.index.name:
+ description: The name of the index on a table.
+ type: string
 
 attributes:
  database:
@@ -79,6 +82,22 @@ metrics:
  monotonic: false
  aggregation: cumulative
  attributes: [database, table, state]
+ postgresql.index.scans:
+ attributes: []
+ description: The number of index scans on a table.
+ enabled: true
+ sum:
+ aggregation: cumulative
+ monotonic: true
+ value_type: int
+ unit: "{scans}"
+ postgresql.index.size:
+ attributes: []
+ description: The size of the index on disk.
+ enabled: true
+ gauge:
+ value_type: int
+ unit: "By"
  postgresql.operations:
  enabled: true
  description: The number of db row operations.

receiver/postgresqlreceiver/scraper.go

@@ -145,6 +145,10 @@ func (p *postgreSQLScraper) scrape(ctx context.Context) (pmetric.Metrics, error)
  defer dbClient.Close()
  p.recordDatabase(now, database, r)
  p.collectTables(ctx, now, dbClient, database, &errs)
+
+ if p.emitMetricsWithResourceAttributes {
+ p.collectIndexes(ctx, now, dbClient, database, &errs)
+ }
  }
 
  return p.mb.Emit(), errs.Combine()
@@ -253,6 +257,30 @@ func (p *postgreSQLScraper) collectTables(ctx context.Context, now pcommon.Times
  }
 }
 
+func (p *postgreSQLScraper) collectIndexes(
+ ctx context.Context,
+ now pcommon.Timestamp,
+ client client,
+ database string,
+ errs *scrapererror.ScrapeErrors,
+) {
+ idxStats, err := client.getIndexStats(ctx, database)
+ if err != nil {
+ errs.AddPartial(1, err)
+ return
+ }
+
+ for _, stat := range idxStats {
+ p.mb.RecordPostgresqlIndexScansDataPoint(now, stat.scans)
+ p.mb.RecordPostgresqlIndexSizeDataPoint(now, stat.size)
+ p.mb.EmitForResource(
+ metadata.WithPostgresqlDatabaseName(stat.database),
+ metadata.WithPostgresqlTableName(stat.table),
+ metadata.WithPostgresqlIndexName(stat.index),
+ )
+ }
+}
+
 func (p *postgreSQLScraper) retrieveDatabaseStats(
  ctx context.Context,
  wg *sync.WaitGroup,