性能视图快照系统表
设置enable_wdr_snapshot为on后,后台快照线程会创建并维护以“SNAP_+视图名称”方式命名的系统表,用于记录各性能视图的快照结果。需要有系统管理员权限才可以访问下列系统表。
- SNAP_PGXC_OS_RUN_INFO
- SNAP_PGXC_WAIT_EVENTS
- SNAP_PGXC_INSTR_UNIQUE_SQL
- SNAP_PGXC_STAT_BAD_BLOCK
- SNAP_PGXC_STAT_BGWRITER
- SNAP_PGXC_STAT_REPLICATION
- SNAP_PGXC_REPLICATION_SLOTS
- SNAP_PGXC_SETTINGS
- SNAP_PGXC_INSTANCE_TIME
- SNAP_GLOBAL_WORKLOAD_TRANSACTION
- SNAP_PGXC_WORKLOAD_SQL_COUNT
- SNAP_PGXC_STAT_DATABASE
- SNAP_GLOBAL_STAT_DATABASE
- SNAP_PGXC_REDO_STAT
- SNAP_GLOBAL_REDO_STAT
- SNAP_PGXC_REL_IOSTAT
- SNAP_GLOBAL_REL_IOSTAT
- SNAP_PGXC_TOTAL_MEMORY_DETAIL
- SNAP_PGXC_NODE_STAT_RESET_TIME
- SNAP_PGXC_SQL_COUNT
- SNAP_GLOBAL_TABLE_STAT
- SNAP_GLOBAL_TABLE_CHANGE_STAT
- SNAP_GLOBAL_COLUMN_TABLE_IO_STAT
- SNAP_GLOBAL_ROW_TABLE_IO_STAT
此类系统表除增加snapshot_id字段(bigint类型)外,其余的字段定义与对应视图相同,且各表的分布键均为snapshot_id。
例如,SNAP_PGXC_OS_RUN_INFO,用于存储PGXC_OS_RUN_INFO视图的快照,其字段新增了snapshot_id,其余字段含义均与PGXC_OS_RUN_INFO视图相同。
- 以上系统表的schema都是dbms_om。
- 禁止从外部修改或删除以上系统表,否则可能引起视图快照相关功能异常。