PGXC_STAT_WAL¶
PGXC_STAT_WAL displays the WAL logs and data page traffic information of the current query. This view is supported only by clusters 8.2.0 and later versions.
Name | Type | Description |
|---|---|---|
query_id | bigint | ID of the current query |
query_start | timestamp | Start time of the query |
global_wal | bigint | Total number of WAL logs generated by the current query in the cluster, in bytes |
global_avg_wal_speed | bigint | Average rate of WAL log generation for the current query in the cluster, in byte/s |
global_datapage | bigint | Total size of data pages generated by the current query in the cluster, in bytes |
global_avg_datapage_speed | bigint | Average rate of data page generation for the current query in the cluster, in byte/s |
min_wal_node | Text | Name of the instance group that generates the smallest volume of WAL logs in the current query |
min_wal | bigint | Minimum WAL logs generated by a node, in bytes |
max_wal_node | Text | Name of the instance group that generates the largest volume of WAL logs in the current query |
max_wal | bigint | Maximum WAL logs generated by a node, in bytes |
min_datapage_node | Text | Name of the instance group that generates the smallest volume of data pages in the current query |
min_data_page | bigint | Minimum data pages generated by a node, in bytes |
max_datapage_node | Text | Name of the instance group that generates the largest volume of data pages in the current query |
max_data_page | bigint | Maximum data pages generated by a node, in bytes |
avg_wal_per_node | bigint | Average WAL logs generated by each node, in bytes |
avg_datapage_per_node | bigint | Average data pages generated by each node, in bytes |
query | Text | Statement that is being executed |
Note
When row-store data is imported in batches without indexes, the Xlogs related to logical new pages are generated during data page copy. If the volume of Xlogs is greater than the default value, flow control will be triggered.
Examples¶
Query the statements that are being executed in the cluster, the total volumes of WAL logs and data pages generated by these statements, their average generation rates, and their distribution on DNs.
SELECT * FROM PGXC_STAT_WAL;
query_id | query_start | global_wal | global_avg_wal_speed | global_datapage | global_avg_datapage_speed | min_wal_node | min_wal | max_wal_node | max_wal | min_datapage_node | min_data_page | max_datapage_node | max_data_page | avg_wal_per_node |
avg_datapage_per_node | query
-------------------+-------------------------------+------------+----------------------+-----------------+---------------------------+--------------+----------+--------------+----------+-------------------+---------------+-------------------+---------------+------------------+-
----------------------+----------------------------------------------
72620543991351767 | 2022-11-10 16:49:47.743291+08 | 7579052 | 419000 | 284057600 | 15740000 | datanode1 | 7579052 | datanode1 | 7579052 | datanode1 | 284057600 | datanode1 | 284057600 | 7579052 |
284057600 | insert into mpptest3 select * from mpptest3;
72620543991351781 | 2022-11-10 16:50:00.616697+08 | 55022176 | 10638000 | 0 | 0 | datanode1 | 55022176 | datanode1 | 55022176 | datanode1 | 0 | datanode1 | 0 | 55022176 |
0 | insert into mpptest1 select * from mpptest1;
(2 rows)