Help Center/ GaussDB(DWS)/ 3.0 Developer Guide/ System Views/ PGXC_OBS_IO_SCHEDULER_PERIODIC_STATS
Updated on 2024-03-14 GMT+08:00
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PGXC_OBS_IO_SCHEDULER_PERIODIC_STATS

Collects statistics on the number of requests and flow control information of different request types (including read, write, and file operations) of OBS I/O Scheduler. This view is supported only by the cloud native data warehouse 3.0.

The first query result displays the statistics from the time when the cluster is started to the time when the query is performed. For details about the columns, see the following table.

Table 1 PGXC_OBS_IO_SCHEDULER_PERIODIC_STATS table columns

Column

Type

Description

node_name

name

Name of a CN or DN, for example, dn_6001_6002.

io_type

char

I/O type. The options are as follows:

  • R (Read)
  • W (Write)
  • S (File operation)

recent_throttled_req_num

int

Number of traffic limiting times between two queries to the view

total_throttled_req_num

int

Total number of traffic limiting times

last_throttled_dur(s)

int8

Time since the last traffic limiting

waiting_req_num

int

Number of queuing requests

mean_tps

numeric(7,2)

Average TPS of the two queries to the view. TPS indicates the number of requests processed per second.

mean_req_size(KB)

int8

Average length of requests between two queries to the view. The unit is KB.

mean_req_latency(ms)

int8

Average latency of requests between two queries to the view. The unit is ms.

max_req_latency(ms)

int8

Maximum latency of requests before two queries to the view. The unit is ms.

mean_bps(KB/s)

int8

Average speed of read or write requests between two queries to the view. The unit is KB/s.

duration(s)

int

Interval between two queries to the view. The unit is seconds.

Example

Run the SELECT * FROM pgxc_obs_io_scheduler_periodic_stats statement to query the view content. The following is an example of the query result: 
SELECT * FROM pgxc_obs_io_scheduler_periodic_stats;

  node_name   | io_type | recent_throttled_req_num | total_throttled_req_num | last_throttled_dur(s) | waiting_req_num | mean_tps | mean_req_size(KB) | mean_req_latency(ms) | max_req_latency(ms) | mean_bps(KB/s) | duration(s)
--------------+---------+--------------------------+-------------------------+-----------------------+-----------------+----------+-------------------+----------------------+---------------------+----------------+-------------
 dn_6001_6002 | S       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         155
 dn_6001_6002 | R       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         155
 dn_6001_6002 | W       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         155
 cn_5001      | S       |                        0 |                       0 |                     0 |               0 |      .03 |                 0 |                  207 |                 519 |              0 |         155
 cn_5001      | R       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         155
 cn_5001      | W       |                        0 |                       0 |                     0 |               0 |      .01 |                 0 |                  288 |                 288 |              0 |         155
(6 rows)

To display 0 before the decimal point in the value of mean_tps, execute set behavior_compat_options='display_leading_zero'.

Run the select * from pgxc_obs_io_scheduler_periodic_stats statement. The following information is displayed: 
SELECT * FROM pgxc_obs_io_scheduler_periodic_stats;

  node_name   | io_type | recent_throttled_req_num | total_throttled_req_num | last_throttled_dur(s) | waiting_req_num | mean_tps | mean_req_size(KB) | mean_req_latency(ms) | max_req_latency(ms) | mean_bps(KB/s) | duration(s)
--------------+---------+--------------------------+-------------------------+-----------------------+-----------------+----------+-------------------+----------------------+---------------------+----------------+-------------
 dn_6001_6002 | S       |                        0 |                       0 |                     0 |               0 |     0.36 |                 0 |                  132 |                 326 |              0 |         177
 dn_6001_6002 | R       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         177
 dn_6001_6002 | W       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         177
 cn_5001      | S       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         177
 cn_5001      | R       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         177
 cn_5001      | W       |                        0 |                       0 |                     0 |               0 |     0.00 |                 0 |                    0 |                   0 |              0 |         177
Parent topic: System Views