## Notes 

Upper bound 

• page_reads 

Page read latency (ms) 

• page_writes 

Page write latency (ms) 

• log_waits 

Log wait latency (ms) 

• get_page 

Latency of get_page()  calls (ms) 

The read latency ( page_reads  column) measures the time from when the read request is sent to the file system thread until the read is complete and has been reported back to the execution thread. The write latency ( page_writes ) is calculated in a similar fashion. The size of the page read to or written from a Disk Data tablespace is always 32 KB. 

Log wait latency ( log_waits  column) is the length of time a page write must wait for the undo log to be flushed, which must be done prior to each page write. 

## 23.5.14.41 The ndbinfo processes Table 

The pgman_time_track_stats  table was added in NDB 8.0.19. 

This table contains information about NDB Cluster node processes; each node is represented by the row in the table. Only nodes that are connected to the cluster are shown in this table. You can obtain information about nodes that are configured but not connected to the cluster from the nodes  and config_nodes tables. 

The processes  table contains the following columns: 

• node_id 

The node’s unique node ID in the cluster 

• node_type 

Type of node (management, data, or API node; see text) 

• node_version 

Version of the NDB  software program running on this node. 

• process_id 

This node’s process ID 

• angel_process_id 

Process ID of this node’s angel process 

