PGXC_WLM_SESSION_HISTORY

PGXC_WLM_SESSION_HISTORY displays load management records after job execution on all CNs. This view is used to query data from GaussDB(DWS), which is periodically cleared every 3 minutes. For more information, refer to GS_WLM_SESSION_HISTORY.

For details about columns in the view, see Table 1.

**Table 1** GS_WLM_SESSION_HISTORY columns
Name	Type	Description
datid	oid	OID of the database this backend is connected to
dbname	text	Name of the database the backend is connected to
schemaname	text	Schema name
nodename	text	Name of the CN where the statement is run
username	text	User name used for connecting to the backend
application_name	text	Name of the application that is connected to the backend
client_addr	inet	IP address of the client connected to this backend. If this column is null, it indicates either that the client is connected via a Unix socket on the server machine or that this is an internal process such as autovacuum.
client_hostname	text	Host name of the connected client, as reported by a reverse DNS lookup of client_addr. This column will only be non-null for IP connections, and only when log_hostname is enabled.
client_port	integer	TCP port number that the client uses for communication with this backend, or -1 if a Unix socket is used
query_band	text	Job type, which is specified by the query_band parameter. The default value is a null string.
block_time	bigint	Duration that a statement is blocked before being executed, including the statement parsing and optimization duration. The unit is ms.
start_time	timestamp with time zone	Time when the statement starts to be run
finish_time	timestamp with time zone	Time when the statement execution ends
duration	bigint	Execution time of a statement. The unit is ms.
estimate_total_time	bigint	Estimated execution time of a statement. The unit is ms.
status	text	Final statement execution status. Its value can be finished (normal) or aborted (abnormal). The statement status here is the execution status of the database server. If the statement is successfully executed on the database server but an error is reported in the result set, the statement status is finished.
abort_info	text	Exception information displayed if the final statement execution status is aborted.
resource_pool	text	Resource pool used by the user
control_group	text	Cgroup used by the statement
estimate_memory	integer	Estimated memory used by a statement on a single instance. The unit is MB. This column takes effect only when the GUC parameter enable_dynamic_workload is set to on.
min_peak_memory	integer	Minimum memory peak of a statement across all DNs. The unit is MB.
max_peak_memory	integer	Maximum memory peak of a statement across all DNs. The unit is MB.
average_peak_memory	integer	Average memory usage during statement execution. The unit is MB.
memory_skew_percent	integer	Memory usage skew of a statement among DNs.
spill_info	text	Statement spill information on all DNs. None indicates that the statement has not been spilled to disks on any DNs. All: The statement has been spilled to disks on all DNs. [a:b]: The statement has been spilled to disks on a of b DNs.
min_spill_size	integer	Minimum spilled data among all DNs when a spill occurs. The unit is MB. The default value is 0.
max_spill_size	integer	Maximum spilled data among all DNs when a spill occurs. The unit is MB. The default value is 0.
average_spill_size	integer	Average spilled data among all DNs when a spill occurs. The unit is MB. The default value is 0.
spill_skew_percent	integer	DN spill skew when a spill occurs
min_dn_time	bigint	Minimum execution time of a statement across all DNs. The unit is ms.
max_dn_time	bigint	Maximum execution time of a statement across all DNs. The unit is ms.
average_dn_time	bigint	Average execution time of a statement across all DNs. The unit is ms.
dntime_skew_percent	integer	Execution time skew of a statement among DNs.
min_cpu_time	bigint	Minimum CPU time of a statement across all DNs. The unit is ms.
max_cpu_time	bigint	Maximum CPU time of a statement across all DNs. The unit is ms.
total_cpu_time	bigint	Total CPU time of a statement across all DNs. The unit is ms.
cpu_skew_percent	integer	CPU time skew of a statement among DNs.
min_peak_iops	integer	Minimum IOPS peak of a statement across all DNs. It is counted by ones in a column-store table and by ten thousands in a row-store table.
max_peak_iops	integer	Maximum IOPS peak of a statement across all DNs. It is counted by ones in a column-store table and by ten thousands in a row-store table.
average_peak_iops	integer	Average IOPS peak of a statement across all DNs. It is counted by ones in a column-store table and by ten thousands in a row-store table.
iops_skew_percent	integer	I/O skew across DNs.
warning	text	Warning. The following warnings and warnings related to SQL self-diagnosis tuning are displayed: Spill file size large than 256MB Broadcast size large than 100MB Early spill Spill times is greater than 3 Spill on memory adaptive Hash table conflict
queryid	bigint	Internal query ID used for statement execution
query	text	Statement to be executed. A maximum of 64 KB of strings can be retained.
query_plan	text	Execution plan of a statement. Specification restrictions: Execution plans are displayed only for DML statements. In 8.2.1.100 and later versions, the number of data binding times is added to the execution plans of Parse Bind Execute (PBE) statements to facilitate statement analysis. The number of data binding times is displayed in the format of PBE bind times: Times.
node_group	text	Logical cluster of the user running the statement
pid	bigint	PID of the backend thread of the statement
lane	text	Fast/Slow lane where the statement is executed
unique_sql_id	bigint	ID of the normalized unique SQL.
session_id	text	Unique identifier of a session in the database system. Its format is session_start_time.tid.node_name.
min_read_bytes	bigint	Minimum I/O read bytes of a statement across all DNs. The unit is byte.
max_read_bytes	bigint	Maximum I/O read bytes of a statement across all DNs. The unit is byte.
average_read_bytes	bigint	Average I/O read bytes of a statement across all DNs.
min_write_bytes	bigint	Minimum I/O write bytes of a statement across all DNs.
max_write_bytes	bigint	Maximum I/O write bytes of a statement across all DNs.
average_write_bytes	bigint	Average I/O write bytes of a statement across all DNs.
recv_pkg	bigint	Total number of communication packages received by a statement across all DNs.
send_pkg	bigint	Total number of communication packages sent by a statement across all DNs.
recv_bytes	bigint	Total received data of the statement stream, in byte.
send_bytes	bigint	Total sent data of the statement stream, in byte.
stmt_type	text	Query type corresponding to the statement.
except_info	text	Information about the exception rule triggered by the statement.
unique_plan_id	bigint	ID of the normalized unique plan.
sql_hash	text	Normalized SQL hash.
plan_hash	text	Normalized plan hash.
use_plan_baseline	text	Indicates whether the bound plan is used for executing the current statement. If is used, the name of the plan_baseline column in pg_plan_baseline is displayed.
outline_name	text	Name of the outline used for the statement plan.
loader_status	text	The JSON string for storing import and export service information is as follows. address: indicates the IP address of the peer cluster. The port number is displayed for the source cluster. direction: indicates the import and export service type. The value can be gds to file, gds from file, gds to pipe, gds from pipe, copy from or copy to. min/max/total_lines/bytes: indicates the minimum value, maximum value, total lines, and bytes of the import and export statements on all DNs.
parse_time	bigint	Total parsing time before the statement is queued (including lexical and syntax parsing, optimization rewriting, and plan generation time), in milliseconds. This column is available only in clusters of version 8.3.0.100 or later.
disk_cache_hit_ratio	numeric(5,2)	Disk cache hit rate. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
disk_cache_disk_read_size	bigint	Total size of data read from disk cache, in MB. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
disk_cache_disk_write_size	bigint	Total size of data written to disk cache, in MB. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
disk_cache_remote_read_size	bigint	Total size of data read remotely from OBS due to disk cache read failure, in MB. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
disk_cache_remote_read_time	bigint	Total number of times data is read remotely from OBS due to disk cache read failure. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
vfs_scan_bytes	bigint	Total number of bytes scanned by the OBS virtual file system in response to upper-layer requests, in bytes. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
vfs_remote_read_bytes	bigint	Total number of bytes actually read from OBS by the OBS virtual file system, in bytes. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
preload_submit_time	bigint	Total time for submitting I/O requests in the prefetching process, in microseconds. This column only applies to OBS 3.0 tables with storage and compute decoupled.
preload_wait_time	bigint	Total time for waiting for I/O requests in the prefetching process, in microseconds. This column only applies to OBS 3.0 tables with storage and compute decoupled.
preload_wait_count	bigint	Total number of times that the prefetching process waits for I/O requests. This column only applies to OBS 3.0 tables with storage and compute decoupled.
disk_cache_load_time	bigint	Total time for reading from disk cache, in microseconds. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
disk_cache_conflict_count	bigint	Number of times a block in the disk cache produces a hash conflict. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
disk_cache_error_count	bigint	Number of disk cache read failures. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
disk_cache_error_code	bigint	Error code for disk cache read failures. Multiple error codes may be generated. If the disk cache fails to be read, OBS remote read is initiated and cache blocks are rewritten. The error code types are as follows: This column only applies to OBS 3.0 tables and foreign tables. 1: A hash conflict occurs in the disk cache block. 2: The generation time of the disk cache block is later than that of the OldestXmin transaction. 4: Invoking the pread system when reading cache files from the disk cache failed. 8: The data version of the disk cache block does not match. 16: The version of the data written to the write cache does not match the latest version. 32: Opening the cache file corresponding to the cache block failed. 64: The size of the data read from the disk cache does not match. 128: The CSN recorded in the disk cache block does not match.
obs_io_req_avg_rtt	bigint	Average Round Trip Time (RTT) for OBS I/O requests, in microseconds. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
obs_io_req_avg_latency	bigint	Average delay for OBS I/O requests, in microseconds. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
obs_io_req_latency_gt_1s	bigint	Number of OBS I/O requests with a latency exceeding 1 second. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
obs_io_req_latency_gt_10s	bigint	Number of OBS I/O requests with a latency exceeding 10 seconds. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
obs_io_req_count	bigint	Total number of OBS I/O requests. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
obs_io_req_retry_count	bigint	Total number of retries for OBS I/O requests. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.
obs_io_req_rate_limit_count	bigint	Total number of times OBS I/O requests are flow-controlled. This column only applies to OBS 3.0 tables and foreign tables with storage and compute decoupled.