You can check I/O statistics and I/O latency distribution by using the polar_stat_io_info and polar_stat_io_latency views.
To use the polar_stat_io_info and polar_stat_io_latency views, you need to create the polar_monitor extension in the database by executing the CREATE EXTENSION polar_monitor statement.
I/O statistics view
The polar_stat_io_info view displays the I/O statistics.
Column | Type | Description |
filetype | text | The file type, such as WAL, DATA, and LOG. |
fileloc | text | The local file. |
open_count | numeric | The number of opened files. |
open_latency_us | double precision | The latency of opening files. Unit: microseconds. |
close_count | numeric | The number of closed files. |
read_count | numeric | The number of read files. |
write_count | numeric | The number of written files. |
read_throughput | numeric | The total length of read files. Unit: bytes. |
write_throughput | numeric | The total length of written files. Unit: bytes. |
read_latency_us | double precision | The total latency of reading files. Unit: microseconds. |
write_latency_us | numeric | The total latency of writing files. Unit: microseconds. |
seek_count | numeric | The number of file addressing times. |
seek_latency_us | double precision | The total latency of addressing files. Unit: microseconds. |
creat_count | numeric | The number of created files. |
creat_latency_us | double precision | The total latency of creating files. Unit: microseconds. |
fsync_count | numeric | The number of file synchronization times. |
fsync_latency_us | double precision | The total latency of synchronizing files. Unit: microseconds. |
falloc_count | numeric | The number of falloc files. |
falloc_latency_us | double precision | The total latency of falloc files. Unit: microseconds. |
polar_stat_io_latency
The polar_stat_io_latency view displays the I/O latency distribution.
Column | Type | Description |
iokind | text | The I/O operation type, such as OPEN, CREATE, READ, and WRITE. |
num_lessthan200us | numeric | The number of times when the I/O latency is less than 200 microseconds. |
num_lessthan400us | numeric | The number of times when the I/O latency is less than 400 microseconds. |
num_lessthan600us | numeric | The number of times when the I/O latency is less than 600 microseconds. |
num_lessthan800us | numeric | The number of times when the I/O latency is less than 800 microseconds. |
num_lessthan1ms | numeric | The number of times when the I/O latency is less than 1 millisecond. |
num_lessthan10ms | numeric | The number of times when the I/O latency is less than 10 milliseconds. |
num_lessthan100ms | numeric | The number of times when the I/O latency is less than 100 milliseconds. |
num_morethan100ms | numeric | The number of times when the I/O latency is greater than 100 milliseconds. |