20.30.19. The `INFORMATION_SCHEMA INNODB_METRICS` Table

This INFORMATION_SCHEMA table presents a wide variety of InnoDB performance information, complementing the specific focus areas of the PERFORMANCE_SCHEMA tables for InnoDB. With simple queries, you can check the overall health of the system. With more detailed queries, you can diagnose issues such as performance bottlenecks, resource shortages, and application issues.

Each monitor represents a point within the InnoDB source code that is instrumented to gather counter information. Each counter can be started, stopped, and reset. You can also perform these actions for a group of counters using their common module name.

Table 20.18. INNODB_METRICS Columns

Column name	Description
`NAME`	Unique name for the counter.
`SUBSYSTEM`	The aspect of `InnoDB` that the metric applies to. See the list following the table for the corresponding module names to use with the `SET GLOBAL` syntax.
`COUNT`	Value since the counter is enabled.
`MAX_COUNT`	Maximum value since the counter is enabled.
`MIN_COUNT`	Minimum value since the counter is enabled.
`AVG_COUNT`	Average value since the counter is enabled.
`COUNT_RESET`	Counter value since it was last reset. (The `_RESET` fields act like the lap counter on a stopwatch: you can measure the activity during some time interval, while the cumulative figures are still available in the `COUNT`, `MAX_COUNT`, and so on fields.)
`MAX_COUNT_RESET`	Maximum counter value since it was last reset.
`MIN_COUNT_RESET`	Minimum counter value since it was last reset.
`AVG_COUNT_RESET`	Average counter value since it was last reset.
`TIME_ENABLED`	Timestamp of last start.
`TIME_DISABLED`	Timestamp of last stop.
`TIME_ELAPSED`	Elapsed time in seconds since the counter started.
`TIME_RESET`	Timestamp of last stop.
`STATUS`	Whether the counter is still running () or stopped ().
`TYPE`	Whether the item is a cumulative counter, or measures the current valueof some resource.
`COMMENT`	Additional description.

Notes:

You must have the PROCESS privilege to query this table.

By default, relatively little data is collected. To start, stop, and reset counters, you set one of the the configuration options innodb_monitor_enable, innodb_monitor_disable, innodb_monitor_reset, or innodb_monitor_reset_all, using the name of the counter, the name of the module, a wildcard match for such a name using the "%" character, or the special keyword all. For example:

-- Turn on a counter:set global innodb_monitor_enable = counter_name;-- Turn off a counter:set global innodb_monitor_disable = counter_name;-- Reset a counter:set global innodb_monitor_reset = counter_name;-- Reset all the counter values:set global innodb_monitor_reset_all = counter_name;-- Turn on a group of counters:set global innodb_monitor_enable = module_name;-- Turn off a group of counters:set global innodb_monitor_enable = module_name;-- Turn on monitor "dml_num_inserts":set global innodb_monitor_enable = dml_num_inserts;-- Reset all values for "dml_num_inserts":set global innodb_monitor_reset_all = dml_num_inserts;-- Reset the counters for all dml monitorsset global innodb_monitor_reset = "dml_%";-- Turn on all monitors for the transaction subsystemset global innodb_monitor_enable = module_trx;-- Turn off all monitorsset global innodb_monitor_disable = all;

The module names correspond to, but are not identical to, the values from the SUBSYSTEM column. Here are the values you can use for module_name with the innodb_monitor_enable and related configuration options, along with the corresponding SUBSYSTEM names:
- module_metadata (subsystem = metadata)
- module_lock (subsystem = lock)
- module_buffer (subsystem = buffer)
- module_buf_page (subsystem = buffer_page_io)
- module_os (subsystem = os)
- module_trx (subsystem = transaction)
- module_purge (subsystem = purge)
- module_compress (subsystem = compression)
- module_file (subsystem = file_system)
- module_index (subsystem = index)
- module_adaptive_hash (subsystem = adaptive_hash_index)
- module_ibuf_system (subsystem = change_buffer)
- module_srv (subsystem = server)
- module_ddl (subsystem = ddl)
- module_dml (subsystem = dml)
- module_log (subsystem = recovery)
- module_icp (subsystem = icp)
Because each counter imposes some degree of runtime overhead on the server, typically you enable more counters on test and development servers during experimentation and benchmarking, and only enable counters on production servers to diagnose known issues or monitor aspects that are likely to be bottlenecks for a particular server and workload.

The items represented in the innodb_metrics table are subject to change, so for the most up-to-date list, query a running MySQL server. As of MySQL 5.6.10, the items include:

mysql: select name, subsystem from information_schema.innodb_metrics order by name;+------------------------------------------+---------------------+| name                                     | subsystem           |+------------------------------------------+---------------------+| adaptive_hash_pages_added                | adaptive_hash_index || adaptive_hash_pages_removed              | adaptive_hash_index || adaptive_hash_rows_added                 | adaptive_hash_index || adaptive_hash_rows_deleted_no_hash_entry | adaptive_hash_index || adaptive_hash_rows_removed               | adaptive_hash_index || adaptive_hash_rows_updated               | adaptive_hash_index || adaptive_hash_searches                   | adaptive_hash_index || adaptive_hash_searches_btree             | adaptive_hash_index || buffer_data_reads                        | buffer              || buffer_data_written                      | buffer              || buffer_flush_adaptive                    | buffer              || buffer_flush_adaptive_pages              | buffer              || buffer_flush_adaptive_total_pages        | buffer              || buffer_flush_avg_page_rate               | buffer              || buffer_flush_background                  | buffer              || buffer_flush_background_pages            | buffer              || buffer_flush_background_total_pages      | buffer              || buffer_flush_batches                     | buffer              || buffer_flush_batch_num_scan              | buffer              || buffer_flush_batch_pages                 | buffer              || buffer_flush_batch_scanned               | buffer              || buffer_flush_batch_scanned_per_call      | buffer              || buffer_flush_batch_total_pages           | buffer              || buffer_flush_lsn_avg_rate                | buffer              || buffer_flush_neighbor                    | buffer              || buffer_flush_neighbor_pages              | buffer              || buffer_flush_neighbor_total_pages        | buffer              || buffer_flush_n_to_flush_requested        | buffer              || buffer_flush_pct_for_dirty               | buffer              || buffer_flush_pct_for_lsn                 | buffer              || buffer_flush_sync                        | buffer              || buffer_flush_sync_pages                  | buffer              || buffer_flush_sync_total_pages            | buffer              || buffer_flush_sync_waits                  | buffer              || buffer_LRU_batches                       | buffer              || buffer_LRU_batch_num_scan                | buffer              || buffer_LRU_batch_pages                   | buffer              || buffer_LRU_batch_scanned                 | buffer              || buffer_LRU_batch_scanned_per_call        | buffer              || buffer_LRU_batch_total_pages             | buffer              || buffer_LRU_get_free_search               | Buffer              || buffer_LRU_search_num_scan               | buffer              || buffer_LRU_search_scanned                | buffer              || buffer_LRU_search_scanned_per_call       | buffer              || buffer_LRU_single_flush_failure_count    | Buffer              || buffer_LRU_single_flush_num_scan         | buffer              || buffer_LRU_single_flush_scanned          | buffer              || buffer_LRU_single_flush_scanned_per_call | buffer              || buffer_LRU_unzip_search_num_scan         | buffer              || buffer_LRU_unzip_search_scanned          | buffer              || buffer_LRU_unzip_search_scanned_per_call | buffer              || buffer_pages_created                     | buffer              || buffer_pages_read                        | buffer              || buffer_pages_written                     | buffer              || buffer_page_read_blob                    | buffer_page_io      || buffer_page_read_fsp_hdr                 | buffer_page_io      || buffer_page_read_ibuf_bitmap             | buffer_page_io      || buffer_page_read_ibuf_free_list          | buffer_page_io      || buffer_page_read_index_ibuf_leaf         | buffer_page_io      || buffer_page_read_index_ibuf_non_leaf     | buffer_page_io      || buffer_page_read_index_inode             | buffer_page_io      || buffer_page_read_index_leaf              | buffer_page_io      || buffer_page_read_index_non_leaf          | buffer_page_io      || buffer_page_read_other                   | buffer_page_io      || buffer_page_read_system_page             | buffer_page_io      || buffer_page_read_trx_system              | buffer_page_io      || buffer_page_read_undo_log                | buffer_page_io      || buffer_page_read_xdes                    | buffer_page_io      || buffer_page_read_zblob                   | buffer_page_io      || buffer_page_read_zblob2                  | buffer_page_io      || buffer_page_written_blob                 | buffer_page_io      || buffer_page_written_fsp_hdr              | buffer_page_io      || buffer_page_written_ibuf_bitmap          | buffer_page_io      || buffer_page_written_ibuf_free_list       | buffer_page_io      || buffer_page_written_index_ibuf_leaf      | buffer_page_io      || buffer_page_written_index_ibuf_non_leaf  | buffer_page_io      || buffer_page_written_index_inode          | buffer_page_io      || buffer_page_written_index_leaf           | buffer_page_io      || buffer_page_written_index_non_leaf       | buffer_page_io      || buffer_page_written_other                | buffer_page_io      || buffer_page_written_system_page          | buffer_page_io      || buffer_page_written_trx_system           | buffer_page_io      || buffer_page_written_undo_log             | buffer_page_io      || buffer_page_written_xdes                 | buffer_page_io      || buffer_page_written_zblob                | buffer_page_io      || buffer_page_written_zblob2               | buffer_page_io      || buffer_pool_bytes_data                   | buffer              || buffer_pool_bytes_dirty                  | buffer              || buffer_pool_pages_data                   | buffer              || buffer_pool_pages_dirty                  | buffer              || buffer_pool_pages_free                   | buffer              || buffer_pool_pages_misc                   | buffer              || buffer_pool_pages_total                  | buffer              || buffer_pool_reads                        | buffer              || buffer_pool_read_ahead                   | buffer              || buffer_pool_read_ahead_evicted           | buffer              || buffer_pool_read_requests                | buffer              || buffer_pool_size                         | server              || buffer_pool_wait_free                    | buffer              || buffer_pool_write_requests               | buffer              || compression_pad_decrements               | compression         || compression_pad_increments               | compression         || compress_pages_compressed                | compression         || compress_pages_decompressed              | compression         || ddl_background_drop_indexes              | ddl                 || ddl_background_drop_tables               | ddl                 || ddl_online_create_index                  | ddl                 || ddl_pending_alter_table                  | ddl                 || dml_deletes                              | dml                 || dml_inserts                              | dml                 || dml_reads                                | dml                 || dml_updates                              | dml                 || file_num_open_files                      | file_system         || ibuf_merges                              | change_buffer       || ibuf_merges_delete                       | change_buffer       || ibuf_merges_delete_mark                  | change_buffer       || ibuf_merges_discard_delete               | change_buffer       || ibuf_merges_discard_delete_mark          | change_buffer       || ibuf_merges_discard_insert               | change_buffer       || ibuf_merges_insert                       | change_buffer       || ibuf_size                                | change_buffer       || icp_attempts                             | icp                 || icp_match                                | icp                 || icp_no_match                             | icp                 || icp_out_of_range                         | icp                 || index_merges                             | index               || index_splits                             | index               || innodb_activity_count                    | server              || innodb_background_drop_table_usec        | server              || innodb_checkpoint_usec                   | server              || innodb_dblwr_pages_written               | server              || innodb_dblwr_writes                      | server              || innodb_dict_lru_usec                     | server              || innodb_ibuf_merge_usec                   | server              || innodb_log_flush_usec                    | server              || innodb_master_active_loops               | server              || innodb_master_idle_loops                 | server              || innodb_master_purge_usec                 | server              || innodb_master_thread_sleeps              | server              || innodb_mem_validate_usec                 | server              || innodb_page_size                         | server              || innodb_rwlock_s_os_waits                 | server              || innodb_rwlock_s_spin_rounds              | server              || innodb_rwlock_s_spin_waits               | server              || innodb_rwlock_x_os_waits                 | server              || innodb_rwlock_x_spin_rounds              | server              || innodb_rwlock_x_spin_waits               | server              || lock_deadlocks                           | lock                || lock_rec_locks                           | lock                || lock_rec_lock_created                    | lock                || lock_rec_lock_removed                    | lock                || lock_rec_lock_requests                   | lock                || lock_rec_lock_waits                      | lock                || lock_row_lock_current_waits              | lock                || lock_row_lock_time                       | lock                || lock_row_lock_time_avg                   | lock                || lock_row_lock_time_max                   | lock                || lock_row_lock_waits                      | lock                || lock_table_locks                         | lock                || lock_table_lock_created                  | lock                || lock_table_lock_removed                  | lock                || lock_table_lock_waits                    | lock                || lock_timeouts                            | lock                || log_checkpoints                          | recovery            || log_lsn_buf_pool_oldest                  | recovery            || log_lsn_checkpoint_age                   | recovery            || log_lsn_current                          | recovery            || log_lsn_last_checkpoint                  | recovery            || log_lsn_last_flush                       | recovery            || log_max_modified_age_async               | recovery            || log_max_modified_age_sync                | recovery            || log_num_log_io                           | recovery            || log_pending_checkpoint_writes            | recovery            || log_pending_log_writes                   | recovery            || log_waits                                | recovery            || log_writes                               | recovery            || log_write_requests                       | recovery            || metadata_mem_pool_size                   | metadata            || metadata_table_handles_closed            | metadata            || metadata_table_handles_opened            | metadata            || metadata_table_reference_count           | metadata            || os_data_fsyncs                           | os                  || os_data_reads                            | os                  || os_data_writes                           | os                  || os_log_bytes_written                     | os                  || os_log_fsyncs                            | os                  || os_log_pending_fsyncs                    | os                  || os_log_pending_writes                    | os                  || os_pending_reads                         | os                  || os_pending_writes                        | os                  || purge_del_mark_records                   | purge               || purge_dml_delay_usec                     | purge               || purge_invoked                            | purge               || purge_resume_count                       | purge               || purge_stop_count                         | purge               || purge_undo_log_pages                     | purge               || purge_upd_exist_or_extern_records        | purge               || trx_active_transactions                  | transaction         || trx_commits_insert_update                | transaction         || trx_nl_ro_commits                        | transaction         || trx_rollbacks                            | transaction         || trx_rollbacks_savepoint                  | transaction         || trx_rollback_active                      | transaction         || trx_ro_commits                           | transaction         || trx_rseg_current_size                    | transaction         || trx_rseg_history_len                     | transaction         || trx_rw_commits                           | transaction         || trx_undo_slots_cached                    | transaction         || trx_undo_slots_used                      | transaction         |+------------------------------------------+---------------------+209 rows in set (0.00 sec)

20.30.19. The INFORMATION_SCHEMA INNODB_METRICS Table

20.30.19. The `INFORMATION_SCHEMA INNODB_METRICS` Table