MySQL 9.3 Reference Manual Including MySQL NDB Cluster 9.3
This section discusses several SQL statements that can prove useful in managing and monitoring a MySQL server that is connected to an NDB Cluster, and in some cases provide information about the cluster itself.
SHOW ENGINE NDB
STATUS,
SHOW ENGINE
NDBCLUSTER STATUS
The output of this statement contains information about the server's connection to the cluster, creation and usage of NDB Cluster objects, and binary logging for NDB Cluster replication.
See Section 15.7.7.17, “SHOW ENGINE Statement”, for a usage example and more detailed information.
This statement can be used to determine whether or not clustering support is enabled in the MySQL server, and if so, whether it is active.
See Section 15.7.7.18, “SHOW ENGINES Statement”, for more detailed information.
SELECT * FROM INFORMATION_SCHEMA.ENGINES [WHERE
ENGINE LIKE 'NDB%']
This is the equivalent of SHOW
ENGINES, but uses the
ENGINES table of the
INFORMATION_SCHEMA database. Unlike the
case with the SHOW ENGINES
statement, it is possible to filter the results using a
LIKE clause, and to select
specific columns to obtain information that may be of use in
scripts. For example, the following query shows whether the
server was built with NDB support
and, if so, whether it is enabled:
mysql>SELECT ENGINE, SUPPORT FROM INFORMATION_SCHEMA.ENGINES->WHERE ENGINE LIKE 'NDB%';+------------+---------+ | ENGINE | SUPPORT | +------------+---------+ | ndbcluster | YES | | ndbinfo | YES | +------------+---------+
If NDB support is not enabled, the
preceding query returns an empty set. See
Section 28.3.13, “The INFORMATION_SCHEMA ENGINES Table”, for more
information.
This statement provides a list of most server system variables
relating to the NDB storage
engine, and their values, as shown here:
mysql> SHOW VARIABLES LIKE 'NDB%';
+--------------------------------------------+----------------------------------+
| Variable_name | Value |
+--------------------------------------------+----------------------------------+
| ndb_allow_copying_alter_table | ON |
| ndb_applier_allow_skip_epoch | OFF |
| ndb_applier_conflict_role | NONE |
| ndb_autoincrement_prefetch_sz | 512 |
| ndb_batch_size | 32768 |
| ndb_blob_read_batch_bytes | 65536 |
| ndb_blob_write_batch_bytes | 65536 |
| ndb_clear_apply_status | ON |
| ndb_cluster_connection_pool | 1 |
| ndb_cluster_connection_pool_nodeids | |
| ndb_connectstring | 127.0.0.1 |
| ndb_data_node_neighbour | 0 |
| ndb_default_column_format | FIXED |
| ndb_deferred_constraints | 0 |
| ndb_distribution | KEYHASH |
| ndb_eventbuffer_free_percent | 20 |
| ndb_eventbuffer_max_alloc | 0 |
| ndb_extra_logging | 1 |
| ndb_force_send | ON |
| ndb_fully_replicated | OFF |
| ndb_index_stat_enable | ON |
| ndb_index_stat_option | loop_enable=1000ms,
loop_idle=1000ms,loop_busy=100ms,update_batch=1,read_batch=4,idle_batch=32,
check_batch=8,check_delay=10m,delete_batch=8,clean_delay=1m,error_batch=4,
error_delay=1m,evict_batch=8,evict_delay=1m,cache_limit=32M,cache_lowpct=90,
zero_total=0 |
| ndb_join_pushdown | ON |
| ndb_log_apply_status | OFF |
| ndb_log_bin | OFF |
| ndb_log_binlog_index | ON |
| ndb_log_empty_epochs | OFF |
| ndb_log_empty_update | OFF |
| ndb_log_exclusive_reads | OFF |
| ndb_log_fail_terminate | OFF |
| ndb_log_orig | OFF |
| ndb_log_transaction_compression | OFF |
| ndb_log_transaction_compression_level_zstd | 3 |
| ndb_log_transaction_dependency | OFF |
| ndb_log_transaction_id | OFF |
| ndb_log_update_as_write | ON |
| ndb_log_update_minimal | OFF |
| ndb_log_updated_only | ON |
| ndb_metadata_check | ON |
| ndb_metadata_check_interval | 60 |
| ndb_metadata_sync | OFF |
| ndb_mgm_tls | relaxed |
| ndb_mgmd_host | 127.0.0.1 |
| ndb_nodeid | 0 |
| ndb_optimization_delay | 10 |
| ndb_optimized_node_selection | 3 |
| ndb_read_backup | ON |
| ndb_recv_thread_activation_threshold | 8 |
| ndb_recv_thread_cpu_mask | |
| ndb_replica_batch_size | 2097152 |
| ndb_replica_blob_write_batch_bytes | 2097152 |
| ndb_report_thresh_binlog_epoch_slip | 10 |
| ndb_report_thresh_binlog_mem_usage | 10 |
| ndb_row_checksum | 1 |
| ndb_schema_dist_lock_wait_timeout | 30 |
| ndb_schema_dist_timeout | 120 |
| ndb_schema_dist_upgrade_allowed | ON |
| ndb_show_foreign_key_mock_tables | OFF |
| ndb_slave_conflict_role | NONE |
| ndb_table_no_logging | OFF |
| ndb_table_temporary | OFF |
| ndb_tls_search_path | $HOME/ndb-tls |
| ndb_use_copying_alter_table | OFF |
| ndb_use_exact_count | OFF |
| ndb_use_transactions | ON |
| ndb_version | 524544 |
| ndb_version_string | ndb-8.4.0 |
| ndb_wait_connected | 120 |
| ndb_wait_setup | 120 |
| ndbinfo_database | ndbinfo |
| ndbinfo_max_bytes | 0 |
| ndbinfo_max_rows | 10 |
| ndbinfo_offline | OFF |
| ndbinfo_show_hidden | OFF |
| ndbinfo_table_prefix | ndb$ |
| ndbinfo_version | 524544 |
+--------------------------------------------+----------------------------------+
74 rows in set (0.01 sec)
See Section 7.1.8, “Server System Variables”, for more information.
SELECT * FROM performance_schema.global_variables
WHERE VARIABLE_NAME LIKE 'NDB%'
This statement is the equivalent of the
SHOW VARIABLES statement
described in the previous item, and provides almost identical
output, as shown here:
mysql>SELECT * FROM performance_schema.global_variables->WHERE VARIABLE_NAME LIKE 'NDB%';+--------------------------------------+---------------------------------------+ | VARIABLE_NAME | VARIABLE_VALUE | +--------------------------------------+---------------------------------------+ | ndb_allow_copying_alter_table | ON | | ndb_autoincrement_prefetch_sz | 512 | | ndb_batch_size | 32768 | | ndb_blob_read_batch_bytes | 65536 | | ndb_blob_write_batch_bytes | 65536 | | ndb_clear_apply_status | ON | | ndb_cluster_connection_pool | 1 | | ndb_cluster_connection_pool_nodeids | | | ndb_connectstring | 127.0.0.1 | | ndb_data_node_neighbour | 0 | | ndb_default_column_format | FIXED | | ndb_deferred_constraints | 0 | | ndb_distribution | KEYHASH | | ndb_eventbuffer_free_percent | 20 | | ndb_eventbuffer_max_alloc | 0 | | ndb_extra_logging | 1 | | ndb_force_send | ON | | ndb_fully_replicated | OFF | | ndb_index_stat_enable | ON | | ndb_index_stat_option | loop_enable=1000ms,loop_idle=1000ms, loop_busy=100ms,update_batch=1,read_batch=4,idle_batch=32,check_batch=8, check_delay=10m,delete_batch=8,clean_delay=1m,error_batch=4,error_delay=1m, evict_batch=8,evict_delay=1m,cache_limit=32M,cache_lowpct=90,zero_total=0 | | ndb_join_pushdown | ON | | ndb_log_apply_status | OFF | | ndb_log_bin | OFF | | ndb_log_binlog_index | ON | | ndb_log_empty_epochs | OFF | | ndb_log_empty_update | OFF | | ndb_log_exclusive_reads | OFF | | ndb_log_orig | OFF | | ndb_log_transaction_id | OFF | | ndb_log_update_as_write | ON | | ndb_log_update_minimal | OFF | | ndb_log_updated_only | ON | | ndb_metadata_check | ON | | ndb_metadata_check_interval | 60 | | ndb_metadata_sync | OFF | | ndb_mgmd_host | 127.0.0.1 | | ndb_nodeid | 0 | | ndb_optimization_delay | 10 | | ndb_optimized_node_selection | 3 | | ndb_read_backup | ON | | ndb_recv_thread_activation_threshold | 8 | | ndb_recv_thread_cpu_mask | | | ndb_report_thresh_binlog_epoch_slip | 10 | | ndb_report_thresh_binlog_mem_usage | 10 | | ndb_row_checksum | 1 | | ndb_schema_dist_lock_wait_timeout | 30 | | ndb_schema_dist_timeout | 120 | | ndb_schema_dist_upgrade_allowed | ON | | ndb_show_foreign_key_mock_tables | OFF | | ndb_slave_conflict_role | NONE | | ndb_table_no_logging | OFF | | ndb_table_temporary | OFF | | ndb_use_copying_alter_table | OFF | | ndb_use_exact_count | OFF | | ndb_use_transactions | ON | | ndb_version | 524308 | | ndb_version_string | ndb-9.2.0 | | ndb_wait_connected | 30 | | ndb_wait_setup | 30 | | ndbinfo_database | ndbinfo | | ndbinfo_max_bytes | 0 | | ndbinfo_max_rows | 10 | | ndbinfo_offline | OFF | | ndbinfo_show_hidden | OFF | | ndbinfo_table_prefix | ndb$ | | ndbinfo_version | 524308 | +--------------------------------------+---------------------------------------+
Unlike the case with the SHOW
VARIABLES statement, it is possible to select
individual columns. For example:
mysql>SELECT VARIABLE_VALUE->FROM performance_schema.global_variables->WHERE VARIABLE_NAME = 'ndb_force_send';+----------------+ | VARIABLE_VALUE | +----------------+ | ON | +----------------+
A more useful query is shown here:
mysql>SELECT VARIABLE_NAME AS Name, VARIABLE_VALUE AS Value>FROM performance_schema.global_variables>WHERE VARIABLE_NAME>IN ('version', 'ndb_version',>'ndb_version_string', 'ndbinfo_version');+--------------------+---------------+ | Name | Value | +--------------------+---------------+ | ndb_version | 524544 | | ndb_version_string | ndb-8.4.0 | | ndbinfo_version | 524544 | | version | 8.4.0-cluster | +--------------------+---------------+ 4 rows in set (0.00 sec)
For more information, see Section 29.12.15, “Performance Schema Status Variable Tables”, and Section 7.1.8, “Server System Variables”.
This statement shows at a glance whether or not the MySQL server is acting as a cluster SQL node, and if so, it provides the MySQL server's cluster node ID, the host name and port for the cluster management server to which it is connected, and the number of data nodes in the cluster, as shown here:
mysql> SHOW STATUS LIKE 'NDB%';
+----------------------------------------------+-------------------------------+
| Variable_name | Value |
+----------------------------------------------+-------------------------------+
| Ndb_metadata_detected_count | 0 |
| Ndb_cluster_node_id | 100 |
| Ndb_config_from_host | 127.0.0.1 |
| Ndb_config_from_port | 1186 |
| Ndb_number_of_data_nodes | 2 |
| Ndb_number_of_ready_data_nodes | 2 |
| Ndb_connect_count | 0 |
| Ndb_execute_count | 0 |
| Ndb_scan_count | 0 |
| Ndb_pruned_scan_count | 0 |
| Ndb_schema_locks_count | 0 |
| Ndb_api_wait_exec_complete_count_session | 0 |
| Ndb_api_wait_scan_result_count_session | 0 |
| Ndb_api_wait_meta_request_count_session | 1 |
| Ndb_api_wait_nanos_count_session | 163446 |
| Ndb_api_bytes_sent_count_session | 60 |
| Ndb_api_bytes_received_count_session | 28 |
| Ndb_api_trans_start_count_session | 0 |
| Ndb_api_trans_commit_count_session | 0 |
| Ndb_api_trans_abort_count_session | 0 |
| Ndb_api_trans_close_count_session | 0 |
| Ndb_api_pk_op_count_session | 0 |
| Ndb_api_uk_op_count_session | 0 |
| Ndb_api_table_scan_count_session | 0 |
| Ndb_api_range_scan_count_session | 0 |
| Ndb_api_pruned_scan_count_session | 0 |
| Ndb_api_scan_batch_count_session | 0 |
| Ndb_api_read_row_count_session | 0 |
| Ndb_api_trans_local_read_row_count_session | 0 |
| Ndb_api_adaptive_send_forced_count_session | 0 |
| Ndb_api_adaptive_send_unforced_count_session | 0 |
| Ndb_api_adaptive_send_deferred_count_session | 0 |
| Ndb_trans_hint_count_session | 0 |
| Ndb_sorted_scan_count | 0 |
| Ndb_pushed_queries_defined | 0 |
| Ndb_pushed_queries_dropped | 0 |
| Ndb_pushed_queries_executed | 0 |
| Ndb_pushed_reads | 0 |
| Ndb_last_commit_epoch_server | 37632503447571 |
| Ndb_last_commit_epoch_session | 0 |
| Ndb_system_name | MC_20191126162038 |
| Ndb_api_event_data_count_injector | 0 |
| Ndb_api_event_nondata_count_injector | 0 |
| Ndb_api_event_bytes_count_injector | 0 |
| Ndb_api_wait_exec_complete_count_slave | 0 |
| Ndb_api_wait_scan_result_count_slave | 0 |
| Ndb_api_wait_meta_request_count_slave | 0 |
| Ndb_api_wait_nanos_count_slave | 0 |
| Ndb_api_bytes_sent_count_slave | 0 |
| Ndb_api_bytes_received_count_slave | 0 |
| Ndb_api_trans_start_count_slave | 0 |
| Ndb_api_trans_commit_count_slave | 0 |
| Ndb_api_trans_abort_count_slave | 0 |
| Ndb_api_trans_close_count_slave | 0 |
| Ndb_api_pk_op_count_slave | 0 |
| Ndb_api_uk_op_count_slave | 0 |
| Ndb_api_table_scan_count_slave | 0 |
| Ndb_api_range_scan_count_slave | 0 |
| Ndb_api_pruned_scan_count_slave | 0 |
| Ndb_api_scan_batch_count_slave | 0 |
| Ndb_api_read_row_count_slave | 0 |
| Ndb_api_trans_local_read_row_count_slave | 0 |
| Ndb_api_adaptive_send_forced_count_slave | 0 |
| Ndb_api_adaptive_send_unforced_count_slave | 0 |
| Ndb_api_adaptive_send_deferred_count_slave | 0 |
| Ndb_slave_max_replicated_epoch | 0 |
| Ndb_api_wait_exec_complete_count | 4 |
| Ndb_api_wait_scan_result_count | 7 |
| Ndb_api_wait_meta_request_count | 172 |
| Ndb_api_wait_nanos_count | 1083548094028 |
| Ndb_api_bytes_sent_count | 4640 |
| Ndb_api_bytes_received_count | 109356 |
| Ndb_api_trans_start_count | 4 |
| Ndb_api_trans_commit_count | 1 |
| Ndb_api_trans_abort_count | 1 |
| Ndb_api_trans_close_count | 4 |
| Ndb_api_pk_op_count | 2 |
| Ndb_api_uk_op_count | 0 |
| Ndb_api_table_scan_count | 1 |
| Ndb_api_range_scan_count | 1 |
| Ndb_api_pruned_scan_count | 0 |
| Ndb_api_scan_batch_count | 1 |
| Ndb_api_read_row_count | 3 |
| Ndb_api_trans_local_read_row_count | 2 |
| Ndb_api_adaptive_send_forced_count | 1 |
| Ndb_api_adaptive_send_unforced_count | 5 |
| Ndb_api_adaptive_send_deferred_count | 0 |
| Ndb_api_event_data_count | 0 |
| Ndb_api_event_nondata_count | 0 |
| Ndb_api_event_bytes_count | 0 |
| Ndb_metadata_excluded_count | 0 |
| Ndb_metadata_synced_count | 0 |
| Ndb_conflict_fn_max | 0 |
| Ndb_conflict_fn_old | 0 |
| Ndb_conflict_fn_max_del_win | 0 |
| Ndb_conflict_fn_epoch | 0 |
| Ndb_conflict_fn_epoch_trans | 0 |
| Ndb_conflict_fn_epoch2 | 0 |
| Ndb_conflict_fn_epoch2_trans | 0 |
| Ndb_conflict_trans_row_conflict_count | 0 |
| Ndb_conflict_trans_row_reject_count | 0 |
| Ndb_conflict_trans_reject_count | 0 |
| Ndb_conflict_trans_detect_iter_count | 0 |
| Ndb_conflict_trans_conflict_commit_count | 0 |
| Ndb_conflict_epoch_delete_delete_count | 0 |
| Ndb_conflict_reflected_op_prepare_count | 0 |
| Ndb_conflict_reflected_op_discard_count | 0 |
| Ndb_conflict_refresh_op_count | 0 |
| Ndb_conflict_last_conflict_epoch | 0 |
| Ndb_conflict_last_stable_epoch | 0 |
| Ndb_index_stat_status | allow:1,enable:1,busy:0,
loop:1000,list:(new:0,update:0,read:0,idle:0,check:0,delete:0,error:0,total:0),
analyze:(queue:0,wait:0),stats:(nostats:0,wait:0),total:(analyze:(all:0,error:0),
query:(all:0,nostats:0,error:0),event:(act:0,skip:0,miss:0),cache:(refresh:0,
clean:0,pinned:0,drop:0,evict:0)),cache:(query:0,clean:0,drop:0,evict:0,
usedpct:0.00,highpct:0.00) |
| Ndb_index_stat_cache_query | 0 |
| Ndb_index_stat_cache_clean | 0 |
+----------------------------------------------+-------------------------------+
If the MySQL server was built with NDB
support, but it is not currently connected to a cluster, every
row in the output of this statement contains a zero or an
empty string for the Value column.
SELECT * FROM performance_schema.global_status WHERE
VARIABLE_NAME LIKE 'NDB%'
This statement provides similar output to the
SHOW STATUS statement discussed
in the previous item. Unlike the case with
SHOW STATUS, it is possible
using SELECT statements to
extract values in SQL for use in scripts for monitoring and
automation purposes.
For more information, see Section 29.12.15, “Performance Schema Status Variable Tables”.
SELECT * FROM INFORMATION_SCHEMA.PLUGINS WHERE
PLUGIN_NAME LIKE 'NDB%'
This statement displays information from the Information
Schema PLUGINS table about
plugins associated with NDB Cluster, such as version, author,
and license, as shown here:
mysql>SELECT * FROM INFORMATION_SCHEMA.PLUGINS>WHERE PLUGIN_NAME LIKE 'NDB%'\G*************************** 1. row *************************** PLUGIN_NAME: ndbcluster PLUGIN_VERSION: 1.0 PLUGIN_STATUS: ACTIVE PLUGIN_TYPE: STORAGE ENGINE PLUGIN_TYPE_VERSION: 90300.0 PLUGIN_LIBRARY: NULL PLUGIN_LIBRARY_VERSION: NULL PLUGIN_AUTHOR: Oracle Corporation PLUGIN_DESCRIPTION: Clustered, fault-tolerant tables PLUGIN_LICENSE: GPL LOAD_OPTION: ON *************************** 2. row *************************** PLUGIN_NAME: ndbinfo PLUGIN_VERSION: 0.1 PLUGIN_STATUS: ACTIVE PLUGIN_TYPE: STORAGE ENGINE PLUGIN_TYPE_VERSION: 90300.0 PLUGIN_LIBRARY: NULL PLUGIN_LIBRARY_VERSION: NULL PLUGIN_AUTHOR: Oracle Corporation PLUGIN_DESCRIPTION: MySQL Cluster system information storage engine PLUGIN_LICENSE: GPL LOAD_OPTION: ON *************************** 3. row *************************** PLUGIN_NAME: ndb_transid_mysql_connection_map PLUGIN_VERSION: 0.1 PLUGIN_STATUS: ACTIVE PLUGIN_TYPE: INFORMATION SCHEMA PLUGIN_TYPE_VERSION: 90300.0 PLUGIN_LIBRARY: NULL PLUGIN_LIBRARY_VERSION: NULL PLUGIN_AUTHOR: Oracle Corporation PLUGIN_DESCRIPTION: Map between MySQL connection ID and NDB transaction ID PLUGIN_LICENSE: GPL LOAD_OPTION: ON
You can also use the SHOW
PLUGINS statement to display this information, but
the output from that statement cannot easily be filtered. See
also The MySQL Plugin API, which describes where and
how the information in the
PLUGINS table is obtained.
You can also query the tables in the
ndbinfo information database for
real-time data about many NDB Cluster operations. See
Section 25.6.17, “ndbinfo: The NDB Cluster Information Database”.