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.

**Table 1** PGXC_STAT_WAL columns
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

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)