MySQL 8.4 Release Notes
25.6.20 快速参考：NDB 集群 SQL 语句
本节讨论了一些用于管理和监控连接到 NDB 集群的 MySQL 服务器的 SQL 语句，以及在某些情况下提供有关集群自身信息的语句。
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SHOW ENGINE NDB STATUS,SHOW ENGINE NDBCLUSTER STATUS此语句的输出包含了服务器对集群的连接信息、NDB 集群对象的创建和使用情况以及 NDB 集群复制的二进制日志记录。
请参阅 第 15.7.7.16 节，“SHOW ENGINE 语句”，了解如何使用这些语句以及获取更多详细信息。
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此语句可用于确定 MySQL 服务器是否启用了集群支持，并且如果启用，是否处于活动状态。
请参阅 第 15.7.7.17 节，“SHOW ENGINES 语句”，获取更多详细信息。
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SELECT * FROM INFORMATION_SCHEMA.ENGINES [WHERE ENGINE LIKE 'NDB%']这与
SHOW ENGINES相同，但使用了ENGINES表来自INFORMATION_SCHEMA数据库。与使用SHOW ENGINES语句不同，这允许通过LIKE子句过滤结果，并选择特定的列以获取可能在脚本中有用的信息。例如，以下查询显示服务器是否支持NDB，以及如果是的话，它是否已启用：mysql> SELECT ENGINE, SUPPORT FROM INFORMATION_SCHEMA.ENGINES -> WHERE ENGINE LIKE 'NDB%'; +------------+---------+ | ENGINE | SUPPORT | +------------+---------+ | ndbcluster | YES | | ndbinfo | YES | +------------+---------+如果不启用
NDB支持，上述查询将返回一个空集。请参阅第 28.3.13 节，“INFORMATION_ SCHEMA ENGINES 表”，获取更多信息。 -
这条语句提供了大多数与
NDB存储引擎相关的服务器系统变量及其值，示例如下：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)请参阅第 7.1.8 节，“服务器系统变量”，获取更多信息。
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SELECT * FROM performance_schema.global_variables WHERE VARIABLE_NAME LIKE 'NDB%'这条语句是
SHOW VARIABLES语句的等效版本，提供几乎相同的输出，示例如下：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-8.4.0 | | 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 | +--------------------------------------+---------------------------------------+与
SHOW VARIABLES语句不同的是，可以选择单独的列。例如：mysql> SELECT VARIABLE_VALUE -> FROM performance_schema.global_variables -> WHERE VARIABLE_NAME = 'ndb_force_send'; +----------------+ | VARIABLE_VALUE | +----------------+ | ON | +----------------+一个更有用的查询如下所示：
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)对于更多信息，请参阅第29.12.15节，“性能_schema状态变量表”，以及第7.1.8节，“服务器系统变量”。
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这个语句可以一目了然地判断MySQL服务器是否作为集群SQL节点运行，如果是的话，它还会提供MySQL服务器的集群节点ID、连接到的集群管理服务器的主机名和端口，以及集群中的数据节点数量，示例如下：
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 | +----------------------------------------------+-------------------------------+如果MySQL服务器被编译支持NDB，但目前未连接到任何集群，那么该语句的输出中每一行的
Value列都包含一个零或空字符串。 -
SELECT * FROM performance_schema.global_status WHERE VARIABLE_NAME LIKE 'NDB%'这条语句提供与
SHOW STATUS语句在前一项中讨论的输出类似。与使用SHOW STATUS不同，这可以通过SELECT语句在SQL中提取值，以便用于监控和自动化脚本的目的。要了解更多信息，请参阅第29.12.15节，“性能_schema 状态变量表”。
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SELECT * FROM INFORMATION_SCHEMA.PLUGINS WHERE PLUGIN_NAME LIKE 'NDB%'这条语句从
PLUGINS表的信息_schema中检索有关与NDB集群相关的插件的信息，例如版本、作者和许可证，如下所示：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: 80400.0 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: 80400.0 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: 80400.0 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您还可以使用
SHOW PLUGINS语句来检索此信息，但该语句的输出不易于过滤。请参阅MySQL插件API，它描述了PLUGINS表中信息的来源和位置。
您还可以查询ndbinfo信息数据库以获取NDB集群的实时数据，了解许多NDB集群操作。请参阅第25.6.17节，“ndbinfo：NDB集群信息数据库”。