feat: add pg_stat_database collectors

Add collectors for pg_stat_database metrics:
- databases_blk: block read/write statistics
- databases_tup: tuple operation statistics
- databases_xact: transaction commit/rollback counts

Author: vyruss

DATA.md

@@ -148,7 +148,10 @@ Instance-level PostgreSQL collectors. Files stored in `postgresql/`.
 | `postgresql/blocking_locks.tsv` | Complex query | Blocking/blocked lock pairs |
 | `postgresql/configuration.tsv` | `pg_settings` | Configuration parameters |
 | `postgresql/databases.tsv` | `pg_database` | Database list |
+| `postgresql/databases_blk.tsv` | `pg_stat_database` | Block read/write statistics |
 | `postgresql/databases_checksums.tsv` | `pg_stat_database` | Checksum failure counts |
+| `postgresql/databases_tup.tsv` | `pg_stat_database` | Tuple operation statistics |
+| `postgresql/databases_xact.tsv` | `pg_stat_database` | Transaction commit/rollback counts |
 | `postgresql/db_role_setting.tsv` | `pg_db_role_setting` | Per-database/role settings |
 | `postgresql/pg_hba.conf` | Data directory | Host-based authentication config |
 | `postgresql/pg_hba_file_rules.tsv` | `pg_hba_file_rules` | Parsed pg_hba.conf rules (PG10+) |

docs/data.md

@@ -149,7 +149,10 @@ Instance-level PostgreSQL collectors. Files stored in `postgresql/`.
 | `postgresql/checkpointer.tsv` | `pg_stat_checkpointer` | Checkpoint statistics (PG17+) |
 | `postgresql/configuration.tsv` | `pg_settings` | Configuration parameters |
 | `postgresql/databases.tsv` | `pg_database` | Database list |
+| `postgresql/databases_blk.tsv` | `pg_stat_database` | Block read/write statistics |
 | `postgresql/databases_checksums.tsv` | `pg_stat_database` | Checksum failure counts |
+| `postgresql/databases_tup.tsv` | `pg_stat_database` | Tuple operation statistics |
+| `postgresql/databases_xact.tsv` | `pg_stat_database` | Transaction commit/rollback counts |
 | `postgresql/db_role_setting.tsv` | `pg_db_role_setting` | Per-database/role settings |
 | `postgresql/pg_hba.conf` | Data directory | Host-based authentication config |
 | `postgresql/pg_hba_file_rules.tsv` | `pg_hba_file_rules` | Parsed pg_hba.conf rules (PG10+) |

postgres_tasks.go

@@ -92,11 +92,26 @@ WHERE NOT blocked_locks.granted`,
 		ArchivePath: "postgresql/databases.tsv",
 		Query:       "SELECT oid, datname, datdba, encoding, datcollate, datctype FROM pg_database ORDER BY datname",
 	},
+	{
+		Name:        "databases_blk",
+		ArchivePath: "postgresql/databases_blk.tsv",
+		Query:       "SELECT datname, blks_read, blks_hit, blk_read_time, blk_write_time FROM pg_stat_database WHERE datname IS NOT NULL ORDER BY datname",
+	},
 	{
 		Name:        "databases_checksums",
 		ArchivePath: "postgresql/databases_checksums.tsv",
 		Query:       "SELECT datname, checksum_failures, checksum_last_failure FROM pg_stat_database WHERE datname IS NOT NULL ORDER BY datname",
 	},
+	{
+		Name:        "databases_tup",
+		ArchivePath: "postgresql/databases_tup.tsv",
+		Query:       "SELECT datname, tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted FROM pg_stat_database WHERE datname IS NOT NULL ORDER BY datname",
+	},
+	{
+		Name:        "databases_xact",
+		ArchivePath: "postgresql/databases_xact.tsv",
+		Query:       "SELECT datname, xact_commit, xact_rollback FROM pg_stat_database WHERE datname IS NOT NULL ORDER BY datname",
+	},
 	{
 		Name:        "db_role_setting",
 		ArchivePath: "postgresql/db_role_setting.tsv",

postgres_test.go

@@ -32,7 +32,10 @@ func TestPostgreSQLCollectors(t *testing.T) {
 		{"checkpointer", "postgresql/checkpointer.tsv"},
 		{"configuration", "postgresql/configuration.tsv"},
 		{"databases", "postgresql/databases.tsv"},
+		{"databases_blk", "postgresql/databases_blk.tsv"},
 		{"databases_checksums", "postgresql/databases_checksums.tsv"},
+		{"databases_tup", "postgresql/databases_tup.tsv"},
+		{"databases_xact", "postgresql/databases_xact.tsv"},
 		{"db_role_setting", "postgresql/db_role_setting.tsv"},
 		{"pg_hba.conf", "postgresql/pg_hba.conf"},
 		{"pg_hba_file_rules", "postgresql/pg_hba_file_rules.tsv"},