MySQL 8.3 Release Notes
有一些类型的统计计数器与 Ndb 对象相关的操作相关，包括启动和关闭（或中止）事务；主键和唯一键操作；表、范围和修剪扫描；线程阻塞等待各种操作的完成；以及 NDBCLUSTER 发送和接收的数据和事件。这些计数器在 NDB 内核中每次 NDB API 调用或数据被发送到或从数据节点接收时递增。mysqld 将这些计数器作为系统状态变量公开；它们的值可以在 SHOW STATUS 的输出中读取，或者通过查询 Performance Schema session_status 或 global_status 表。通过比较语句在 NDB 表上操作之前和之后的值，可以观察到相应的操作在 API 级别上的成本。
您可以使用以下 SHOW STATUS 语句列出所有这些状态变量：
mysql> SHOW STATUS LIKE 'ndb_api%';
+----------------------------------------------+-----------+
| Variable_name | Value |
+----------------------------------------------+-----------+
| Ndb_api_wait_exec_complete_count | 297 |
| Ndb_api_wait_scan_result_count | 0 |
| Ndb_api_wait_meta_request_count | 321 |
| Ndb_api_wait_nanos_count | 228438645 |
| Ndb_api_bytes_sent_count | 33988 |
| Ndb_api_bytes_received_count | 66236 |
| Ndb_api_trans_start_count | 148 |
| Ndb_api_trans_commit_count | 148 |
| Ndb_api_trans_abort_count | 0 |
| Ndb_api_trans_close_count | 148 |
| Ndb_api_pk_op_count | 151 |
| Ndb_api_uk_op_count | 0 |
| Ndb_api_table_scan_count | 0 |
| Ndb_api_range_scan_count | 0 |
| Ndb_api_pruned_scan_count | 0 |
| Ndb_api_scan_batch_count | 0 |
| Ndb_api_read_row_count | 147 |
| Ndb_api_trans_local_read_row_count | 37 |
| Ndb_api_adaptive_send_forced_count | 3 |
| Ndb_api_adaptive_send_unforced_count | 294 |
| 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_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_api_wait_exec_complete_count_replica | 0 |
| Ndb_api_wait_scan_result_count_replica | 0 |
| Ndb_api_wait_meta_request_count_replica | 0 |
| Ndb_api_wait_nanos_count_replica | 0 |
| Ndb_api_bytes_sent_count_replica | 0 |
| Ndb_api_bytes_received_count_replica | 0 |
| Ndb_api_trans_start_count_replica | 0 |
| Ndb_api_trans_commit_count_replica | 0 |
| Ndb_api_trans_abort_count_replica | 0 |
| Ndb_api_trans_close_count_replica | 0 |
| Ndb_api_pk_op_count_replica | 0 |
| Ndb_api_uk_op_count_replica | 0 |
| Ndb_api_table_scan_count_replica | 0 |
| Ndb_api_range_scan_count_replica | 0 |
| Ndb_api_pruned_scan_count_replica | 0 |
| Ndb_api_scan_batch_count_replica | 0 |
| Ndb_api_read_row_count_replica | 0 |
| Ndb_api_trans_local_read_row_count_replica | 0 |
| Ndb_api_adaptive_send_forced_count_replica | 0 |
| Ndb_api_adaptive_send_unforced_count_replica | 0 |
| Ndb_api_adaptive_send_deferred_count_replica | 0 |
| 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_session | 0 |
| Ndb_api_wait_scan_result_count_session | 0 |
| Ndb_api_wait_meta_request_count_session | 0 |
| Ndb_api_wait_nanos_count_session | 0 |
| Ndb_api_bytes_sent_count_session | 0 |
| Ndb_api_bytes_received_count_session | 0 |
| 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 |
+----------------------------------------------+-----------+
90 rows in set (0.01 sec)这些状态变量也可以从 Performance Schema session_status 和 global_status 表中获得，如下所示：
mysql> SELECT * FROM performance_schema.session_status
-> WHERE VARIABLE_NAME LIKE 'ndb_api%';
+----------------------------------------------+----------------+
| VARIABLE_NAME | VARIABLE_VALUE |
+----------------------------------------------+----------------+
| Ndb_api_wait_exec_complete_count | 617 |
| Ndb_api_wait_scan_result_count | 0 |
| Ndb_api_wait_meta_request_count | 649 |
| Ndb_api_wait_nanos_count | 335663491 |
| Ndb_api_bytes_sent_count | 65764 |
| Ndb_api_bytes_received_count | 86940 |
| Ndb_api_trans_start_count | 308 |
| Ndb_api_trans_commit_count | 308 |
| Ndb_api_trans_abort_count | 0 |
| Ndb_api_trans_close_count | 308 |
| Ndb_api_pk_op_count | 311 |
| Ndb_api_uk_op_count | 0 |
| Ndb_api_table_scan_count | 0 |
| Ndb_api_range_scan_count | 0 |
| Ndb_api_pruned_scan_count | 0 |
| Ndb_api_scan_batch_count | 0 |
| Ndb_api_read_row_count | 307 |
| Ndb_api_trans_local_read_row_count | 77 |
| Ndb_api_adaptive_send_forced_count | 3 |
| Ndb_api_adaptive_send_unforced_count | 614 |
| 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_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_api_wait_exec_complete_count_replica | 0 |
| Ndb_api_wait_scan_result_count_replica | 0 |
| Ndb_api_wait_meta_request_count_replica | 0 |
| Ndb_api_wait_nanos_count_replica | 0 |
| Ndb_api_bytes_sent_count_replica | 0 |
| Ndb_api_bytes_received_count_replica | 0 |
| Ndb_api_trans_start_count_replica | 0 |
| Ndb_api_trans_commit_count_replica | 0 |
| Ndb_api_trans_abort_count_replica | 0 |
| Ndb_api_trans_close_count_replica | 0 |
| Ndb_api_pk_op_count_replica | 0 |
| Ndb_api_uk_op_count_replica | 0 |
| Ndb_api_table_scan_count_replica | 0 |
| Ndb_api_range_scan_count_replica | 0 |
| Ndb_api_pruned_scan_count_replica | 0 |
| Ndb_api_scan_batch_count_replica | 0 |
| Ndb_api_read_row_count_replica | 0 |
| Ndb_api_trans_local_read_row_count_replica | 0 |
| Ndb_api_adaptive_send_forced_count_replica | 0 |
| Ndb_api_adaptive_send_unforced_count_replica | 0 |
| Ndb_api_adaptive_send_deferred_count_replica | 0 |
| 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_session | 0 |
| Ndb_api_wait_scan_result_count_session | 0 |
| Ndb_api_wait_meta_request_count_session | 0 |
| Ndb_api_wait_nanos_count_session | 0 |
| Ndb_api_bytes_sent_count_session | 0 |
| Ndb_api_bytes_received_count_session | 0 |
| 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 |
+----------------------------------------------+----------------+
90 rows in set (0.01 sec)
mysql> SELECT * FROM performance_schema.global_status
-> WHERE VARIABLE_NAME LIKE 'ndb_api%';
+----------------------------------------------+----------------+
| VARIABLE_NAME | VARIABLE_VALUE |
+----------------------------------------------+----------------+
| Ndb_api_wait_exec_complete_count | 741 |
| Ndb_api_wait_scan_result_count | 0 |
| Ndb_api_wait_meta_request_count | 777 |
| Ndb_api_wait_nanos_count | 373888309 |
| Ndb_api_bytes_sent_count | 78124 |
| Ndb_api_bytes_received_count | 94988 |
| Ndb_api_trans_start_count | 370 |
| Ndb_api_trans_commit_count | 370 |
| Ndb_api_trans_abort_count | 0 |
| Ndb_api_trans_close_count | 370 |
| Ndb_api_pk_op_count | 373 |
| Ndb_api_uk_op_count | 0 |
| Ndb_api_table_scan_count | 0 |
| Ndb_api_range_scan_count | 0 |
| Ndb_api_pruned_scan_count | 0 |
| Ndb_api_scan_batch_count | 0 |
| Ndb_api_read_row_count | 369 |
| Ndb_api_trans_local_read_row_count | 93 |
| Ndb_api_adaptive_send_forced_count | 3 |
| Ndb_api_adaptive_send_unforced_count | 738 |
| 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_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_api_wait_exec_complete_count_replica | 0 |
| Ndb_api_wait_scan_result_count_replica | 0 |
| Ndb_api_wait_meta_request_count_replica | 0 |
| Ndb_api_wait_nanos_count_replica | 0 |
| Ndb_api_bytes_sent_count_replica | 0 |
| Ndb_api_bytes_received_count_replica | 0 |
| Ndb_api_trans_start_count_replica | 0 |
| Ndb_api_trans_commit_count_replica | 0 |
| Ndb_api_trans_abort_count_replica | 0 |
| Ndb_api_trans_close_count_replica | 0 |
| Ndb_api_pk_op_count_replica | 0 |
| Ndb_api_uk_op_count_replica | 0 |
| Ndb_api_table_scan_count_replica | 0 |
| Ndb_api_range_scan_count_replica | 0 |
| Ndb_api_pruned_scan_count_replica | 0 |
| Ndb_api_scan_batch_count_replica | 0 |
| Ndb_api_read_row_count_replica | 0 |
| Ndb_api_trans_local_read_row_count_replica | 0 |
| Ndb_api_adaptive_send_forced_count_replica | 0 |
| Ndb_api_adaptive_send_unforced_count_replica | 0 |
| Ndb_api_adaptive_send_deferred_count_replica | 0 |
| 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_session | 0 |
| Ndb_api_wait_scan_result_count_session | 0 |
| Ndb_api_wait_meta_request_count_session | 0 |
| Ndb_api_wait_nanos_count_session | 0 |
| Ndb_api_bytes_sent_count_session | 0 |
| Ndb_api_bytes_received_count_session | 0 |
| 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 |
+----------------------------------------------+----------------+
90 rows in set (0.01 sec)每个 Ndb 对象都有其自己的计数器。NDB API 应用程序可以读取这些计数器的值，以便优化或监控。对于使用多个 Ndb 对象的多线程客户端，也可以获得所有 Ndb 对象的总计数器视图，属于给定的 Ndb_cluster_connection。
有四个集合的这些计数器被公开。一个集合仅适用于当前会话；其他三个是全局的。尽管它们的值可以作为会话或全局状态变量在 mysql 客户端中获得。这意味着使用 SHOW STATUS 时指定 SESSION 或 GLOBAL 关键字对 NDB API 统计状态变量的值没有影响，并且每个变量的值在从等效的 session_status 或 global_status 表中获得时相同。
-
会话计数器（会话特定）
会话计数器与当前会话中使用的
Ndb对象相关。其他 MySQL 客户端对这些对象的使用不会影响这些计数。为了避免与标准 MySQL 会话变量混淆，我们将这些变量称为 “
_session变量”，带有前导下划线。 -
副本计数器（全局）
这组计数器与replica SQL线程使用的
Ndb对象相关，如果该mysqld不作为副本，或者不使用NDB表，那么所有这些计数都是0。我们将相关的状态变量称为“
_replica变量”(带有前导下划线)。 -
Injector计数器（全局）
Injector计数器与binary log injector线程使用的
Ndb对象相关，即使不写二进制日志，mysqld进程仍然监听一些事件，如架构更改。我们将状态变量对应的NDB API injector计数器称为“
_injector变量”(带有前导下划线)。 -
服务器（全局）计数器（全局）
这组计数器与当前
Ndb对象相关，包括所有MySQL客户端应用程序、replica SQL线程（如果有）、binary log injector和NDB实用程序线程。我们将状态变量对应的计数器称为“全局变量”或“mysqld-级变量”。
您可以通过过滤变量名称中的子串session、replica或injector(连同公共前缀Ndb_api)来获取特定集合的变量值。对于<_session 变量，可以这样做：
mysql> SHOW STATUS LIKE 'ndb_api%session';
+----------------------------------------------+-------+
| Variable_name | Value |
+----------------------------------------------+-------+
| Ndb_api_wait_exec_complete_count_session | 0 |
| Ndb_api_wait_scan_result_count_session | 0 |
| Ndb_api_wait_meta_request_count_session | 0 |
| Ndb_api_wait_nanos_count_session | 0 |
| Ndb_api_bytes_sent_count_session | 0 |
| Ndb_api_bytes_received_count_session | 0 |
| 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 |
+----------------------------------------------+-------+
21 rows in set (0.00 sec)要获取NDB API mysqld-级状态变量的列表，过滤变量名称以ndb_api开头，以_count结尾，如下所示：
mysql> SELECT * FROM performance_schema.session_status
-> WHERE VARIABLE_NAME LIKE 'ndb_api%count';
+------------------------------------+----------------+
| VARIABLE_NAME | VARIABLE_VALUE |
+------------------------------------+----------------+
| NDB_API_WAIT_EXEC_COMPLETE_COUNT | 4 |
| NDB_API_WAIT_SCAN_RESULT_COUNT | 3 |
| NDB_API_WAIT_META_REQUEST_COUNT | 28 |
| NDB_API_WAIT_NANOS_COUNT | 53756398 |
| NDB_API_BYTES_SENT_COUNT | 1060 |
| NDB_API_BYTES_RECEIVED_COUNT | 9724 |
| NDB_API_TRANS_START_COUNT | 3 |
| NDB_API_TRANS_COMMIT_COUNT | 2 |
| NDB_API_TRANS_ABORT_COUNT | 0 |
| NDB_API_TRANS_CLOSE_COUNT | 3 |
| NDB_API_PK_OP_COUNT | 2 |
| NDB_API_UK_OP_COUNT | 0 |
| NDB_API_TABLE_SCAN_COUNT | 1 |
| NDB_API_RANGE_SCAN_COUNT | 0 |
| NDB_API_PRUNED_SCAN_COUNT | 0 |
| NDB_API_SCAN_BATCH_COUNT | 0 |
| NDB_API_READ_ROW_COUNT | 2 |
| NDB_API_TRANS_LOCAL_READ_ROW_COUNT | 2 |
| NDB_API_EVENT_DATA_COUNT | 0 |
| NDB_API_EVENT_NONDATA_COUNT | 0 |
| NDB_API_EVENT_BYTES_COUNT | 0 |
+------------------------------------+----------------+
21 rows in set (0.09 sec)并不是所有计数器都反映在所有4个集合的状态变量中。对于事件计数器DataEventsRecvdCount、NondataEventsRecvdCount和EventBytesRecvdCount，只有_injector和mysqld-级NDB API状态变量可用：
mysql> SHOW STATUS LIKE 'ndb_api%event%';
+--------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------+-------+
| Ndb_api_event_data_count_injector | 0 |
| Ndb_api_event_nondata_count_injector | 0 |
| Ndb_api_event_bytes_count_injector | 0 |
| Ndb_api_event_data_count | 0 |
| Ndb_api_event_nondata_count | 0 |
| Ndb_api_event_bytes_count | 0 |
+--------------------------------------+-------+
6 rows in set (0.00 sec)_injector状态变量不适用于任何其他NDB API计数器，如下所示：
mysql> SHOW STATUS LIKE 'ndb_api%injector%';
+--------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------+-------+
| Ndb_api_event_data_count_injector | 0 |
| Ndb_api_event_nondata_count_injector | 0 |
| Ndb_api_event_bytes_count_injector | 0 |
+--------------------------------------+-------+
3 rows in set (0.00 sec)状态变量的名称可以轻松地与对应的计数器名称关联。每个NDB API统计计数器都在以下表中列出，连同描述和对应的MySQL服务器状态变量名称。
表25.67 NDB API统计计数器
| Counter Name | Description | Status Variables (by statistic type):
|
|---|---|---|
WaitExecCompleteCount |
线程等待执行操作完成的次数，包括所有execute()调用，以及blob操作和自动递增不visible to clients的隐式执行。 |
|
WaitScanResultCount |
线程等待扫描信号的次数，例如等待附加结果或扫描关闭。 | |
WaitMetaRequestCount |
线程被阻塞等待元数据信号的次数；这可能发生在等待DDL操作或等待epoch开始（或结束）时。 | |
WaitNanosCount |
等待某种类型的信号从数据节点花费的总时间（以纳秒为单位）。 | |
BytesSentCount |
发送到数据节点的数据量（以字节为单位） | |
BytesRecvdCount |
从数据节点接收的数据量（以字节为单位） | |
TransStartCount |
启动的事务数。 | |
TransCommitCount |
提交的事务数。 | |
TransAbortCount |
事务被中止的数量。 | |
TransCloseCount |
事务被中止的数量。（这个值可能大于TransCommitCount和TransAbortCount的总和。） |
|
PkOpCount |
基于或使用主键的操作数量。这包括 blob-part 表操作、隐式解锁操作和自动递增操作，以及 MySQL 客户端通常可见的主键操作。 | |
UkOpCount |
基于或使用唯一键的操作数量。 | |
TableScanCount |
已经启动的表扫描数量。这包括内部表的扫描。 | |
RangeScanCount |
已经启动的范围扫描数量。 | |
PrunedScanCount |
扫描被修剪到单个分区的次数。 | |
ScanBatchCount |
从单个片段接收的扫描结果批次数。（在这个上下文中，批次是指来自单个片段的扫描结果集。） | |
ReadRowCount |
总共读取的行数，包括使用主键、唯一键和扫描操作读取的行数。 | |
TransLocalReadRowCount |
在同一个节点上读取的行数，该节点是事务正在运行的节点。 | |
DataEventsRecvdCount |
接收到的行更改事件数。 |
|
NondataEventsRecvdCount |
接收到的非行更改事件数。 | |
EventBytesRecvdCount |
接收到的事件字节数。 |
要查看所有已提交事务的计数，即所有 TransCommitCount 计数器状态变量，可以使用 SHOW STATUS 语句并过滤结果以查找子串 trans_commit_count，如下所示：
mysql> SHOW STATUS LIKE '%trans_commit_count%';
+------------------------------------+-------+
| Variable_name | Value |
+------------------------------------+-------+
| Ndb_api_trans_commit_count_session | 1 |
| Ndb_api_trans_commit_count_slave | 0 |
| Ndb_api_trans_commit_count | 2 |
+------------------------------------+-------+
3 rows in set (0.00 sec)从中可以确定在当前 mysql 客户端会话中提交了 1 个事务，而在该 mysqld 重新启动以来提交了 2 个事务。
可以通过比较相应的 _session 状态变量在执行特定 SQL 语句前后的值来查看 NDB API 计数器如何递增。例如，在获取初始值后，我们在 test 数据库中创建了一个名为 t 的 NDB 表，该表只有一个列：
mysql> SHOW STATUS LIKE 'ndb_api%session%';
+--------------------------------------------+--------+
| Variable_name | Value |
+--------------------------------------------+--------+
| Ndb_api_wait_exec_complete_count_session | 2 |
| Ndb_api_wait_scan_result_count_session | 0 |
| Ndb_api_wait_meta_request_count_session | 3 |
| Ndb_api_wait_nanos_count_session | 820705 |
| Ndb_api_bytes_sent_count_session | 132 |
| Ndb_api_bytes_received_count_session | 372 |
| Ndb_api_trans_start_count_session | 1 |
| Ndb_api_trans_commit_count_session | 1 |
| Ndb_api_trans_abort_count_session | 0 |
| Ndb_api_trans_close_count_session | 1 |
| Ndb_api_pk_op_count_session | 1 |
| 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 | 1 |
| Ndb_api_trans_local_read_row_count_session | 1 |
+--------------------------------------------+--------+
18 rows in set (0.00 sec)
mysql> USE test;
Database changed
mysql> CREATE TABLE t (c INT) ENGINE NDBCLUSTER;
Query OK, 0 rows affected (0.85 sec)现在可以执行新的 SHOW STATUS 语句并观察更改，如下所示（更改的行以高亮显示）：
mysql> SHOW STATUS LIKE 'ndb_api%session%';
+--------------------------------------------+-----------+
| Variable_name | Value |
+--------------------------------------------+-----------+
| Ndb_api_wait_exec_complete_count_session | 8 |
| Ndb_api_wait_scan_result_count_session | 0 |
| Ndb_api_wait_meta_request_count_session | 17 |
| Ndb_api_wait_nanos_count_session | 706871709 |
| Ndb_api_bytes_sent_count_session | 2376 |
| Ndb_api_bytes_received_count_session | 3844 |
| Ndb_api_trans_start_count_session | 4 |
| Ndb_api_trans_commit_count_session | 4 |
| Ndb_api_trans_abort_count_session | 0 |
| Ndb_api_trans_close_count_session | 4 |
| Ndb_api_pk_op_count_session | 6 |
| 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 | 2 |
| Ndb_api_trans_local_read_row_count_session | 1 |
+--------------------------------------------+-----------+
18 rows in set (0.00 sec)类似地，可以看到插入行到 t 时 NDB API 统计计数器的更改：插入行，然后运行相同的 SHOW STATUS 语句，如下所示：
mysql> INSERT INTO t VALUES (100);
Query OK, 1 row affected (0.00 sec)
mysql> SHOW STATUS LIKE 'ndb_api%session%';
+--------------------------------------------+-----------+
| Variable_name | Value |
+--------------------------------------------+-----------+
| Ndb_api_wait_exec_complete_count_session | 11 |
| Ndb_api_wait_scan_result_count_session | 6 |
| Ndb_api_wait_meta_request_count_session | 20 |
| Ndb_api_wait_nanos_count_session | 707370418 |
| Ndb_api_bytes_sent_count_session | 2724 |
| Ndb_api_bytes_received_count_session | 4116 |
| Ndb_api_trans_start_count_session | 7 |
| Ndb_api_trans_commit_count_session | 6 |
| Ndb_api_trans_abort_count_session | 0 |
| Ndb_api_trans_close_count_session | 7 |
| Ndb_api_pk_op_count_session | 8 |
| Ndb_api_uk_op_count_session | 0 |
| Ndb_api_table_scan_count_session | 1 |
| 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 | 3 |
| Ndb_api_trans_local_read_row_count_session | 2 |
+--------------------------------------------+-----------+
18 rows in set (0.00 sec)我们可以从这些结果中观察到以下几点：
-
尽管我们创建了
t而没有明确的主键，但是在创建过程中执行了 5 次主键操作（Ndb_api_pk_op_count_session的“before”和“after”值之间的差异，或者 6 减去 1）。这反映了使用NDB存储引擎的所有表的隐藏主键特性。 -
通过比较
Ndb_api_wait_nanos_count_session的连续值，我们可以看到 NDB API 操作实现CREATE TABLE语句比执行INSERT语句等待数据节点的响应时间更长（706871709 - 820705 = 706051004 纳秒，约 0.7 秒）。在 mysql 客户端中报告的这些语句的执行时间大致与这些数字相符。在没有足够的纳秒时间分辨率的平台上，小的
WaitNanosCountNDB API 计数器值的变化可能不会在Ndb_api_wait_nanos_count_session、Ndb_api_wait_nanos_count_replica或Ndb_api_wait_nanos_count的值中可见。 -
该
INSERT语句增加了ReadRowCount和TransLocalReadRowCountNDB API 统计计数器的值，如Ndb_api_read_row_count_session和Ndb_api_trans_local_read_row_count_session的增加值所反映。