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22.5.10.32 The ndbinfo pgman_time_track_stats Table
This table provides information regarding the latency of disk operations for NDB Cluster Disk Data tablespaces.
The following table provides information about the columns in
the pgman_time_track_stats table. For each
column, the table shows the name, data type, and a brief
description. Additional information can be found in the notes
following the table.
Table 22.351 Columns of the pgman_time_track_stats table
| Column Name | Type | Description |
|---|---|---|
node_id |
integer | Unique node ID of this node in the cluster |
block_number |
integer | Block number (from blocks table) |
block_instance |
integer | Block instance number |
upper_bound |
integer | Upper bound |
page_reads |
integer | Page read latency (ms) |
page_writes |
integer | Page write latency (ms) |
log_waits |
integer | Log wait latency (ms) |
get_page |
integer | 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.
The pgman_time_track_stats table was added in
NDB 8.0.19.
Document created the 26/06/2006, last modified the 26/10/2018
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