Help Center/ GaussDB/ Developer Guide(Centralized_2.x)/ SQL Reference/ Functions and Operators/ System Administration Functions/ Other Functions

Updated on 2023-10-23 GMT+08:00

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Other Functions

plan_seed()
Description: Obtains the seed value of the previous query statement (internal use).

Return type: int

pg_stat_get_env()

Description: Obtains the environment variable information of the current node. Only users with the sysadmin or monitor admin permission can access the environment variable information.

Return type: record

Example:

openGauss=# select pg_stat_get_env();
                                                                              pg_stat_get_env
---------------------------------------------------------------------------------------------------------------------------------------
 (sgnode,"localhost,XXX.XXX.XXX.XXX",28589,26000,/home/omm,/home/omm/data/single_node,pg_log)
(1 row)

pg_catalog.plancache_clean()
Description: Clears the global plan cache that is not used on nodes.

Return type: Boolean
pg_catalog.plancache_status()
Description: Displays information about the global plan cache on nodes. The information returned by the function is the same as that in GLOBAL_PLANCACHE_STATUS.

Return type: record
textlen(text)
Description: Provides the method of querying the logical length of text.

Return type: int
threadpool_status()
Description: Displays the status of worker threads and sessions in the thread pool.

Return type: record
get_local_active_session()
Description: Provides sampling records of the historical active sessions stored in the memory of the current node.

Return type: record
pg_stat_get_thread()
Description: Provides status information about all threads on the current node. Users with the sysadmin or monitor admin permission can view information about all threads, and common users can view only their own thread information.

Return type: record
pg_stat_get_sql_count()
Description: Provides the counts of the SELECT, UPDATE, INSERT, DELETE, and MERGE INTO statements executed on the current node. Users with the sysadmin or monitor admin permission can view information about all users, and common users can view only their own statistics.

Return type: record
pg_stat_get_data_senders()
Description: Provides detailed information about the data-copy sender thread active at the moment.

Return type: record
get_wait_event_info()
Description: Provides detailed information about the wait event.

Return type: record

generate_wdr_report(begin_snap_id bigint, end_snap_id bigint, report_type cstring, report_scope cstring, node_name cstring)

Description: Generates system diagnosis reports based on two snapshots. You need to run the command in the postgres database. By default, the initial user or users with the monadmin permission can access the database. The result can be queried only in the system database but cannot be queried in the user database.

Return type: record

**Table 1** generate_wdr_report parameter description
Parameter	Description	Range
begin_snap_id	Snapshot ID that starts the diagnosis report period.	N/A
end_snap_id	Snapshot ID that ends the diagnosis report period. By default, the value of end_snap_id is greater than that of begin_snap_id.	N/A
report_type	Specifies the type of the generated report.	summary detail all: Both summary and detail types are included.
report_scope	Specifies the scope for a report to be generated.	cluster: database-level information node: node-level information
node_name	When report_scope is set to node, set this parameter to the name of the corresponding node. (You can run the *select from pg_node_env; command to query the node name.) If report_scope is set to cluster, this parameter can be omitted, left blank, or set to NULL**.	cluster: This value is omitted, left blank or set to NULL. node: a node name in GaussDB

create_wdr_snapshot()
Description: Manually generates system diagnosis snapshots. This function requires the sysadmin permission.

Return type: text
kill_snapshot()
Description: Kills the WDR snapshot backend thread. Users who invoke this function must have the SYSADMIN permission, the REPLICATION permission, or inherit the gs_role_replication permission of the built-in role.

Return type: void
capture_view_to_json(text,integer)
Description: Saves the view result to the directory specified by GUC: perf_directory. If is_crossdb is set to 1, the view is accessed once for all databases. If the value of is_crossdb is 0, the current database is accessed only once. Only users with the sysadmin or monitor admin permission can execute this function.

Return type: int

reset_unique_sql

Description: Clears the unique SQL statements in the memory of the database node. (The sysadmin permission is required.)

Return type: Boolean

**Table 2** reset_unique_sql parameter description
Parameter	Type	Description
scope	text	Clearance scope type. The options are as follows: GLOBAL: Clears all nodes. If the value is GLOBAL, this function can be executed only on the primary node. LOCAL: Clears the current node.
clean_type	text	BY_USERID: Unique SQL statements are cleared based on user IDs. BY_CNID: Unique SQL statements are cleared based on primary node IDs. ALL: All data is cleared.
clean_value	int8	Clearance value corresponding to the clearance type.

wdr_xdb_query(db_name_str text, query text)
Description: Provides the capability of executing local cross-database queries. For example, when connecting to the Postgres database, access tables in the test database.
```
select col1 from wdr_xdb_query('dbname=test','select col1 from t1') as dd(col1 int);
```
Return type: record
pg_wlm_jump_queue(pid int)
Description: Moves a task to the top of the queue of the primary node of the database.

Return type: Boolean
- true: success
- false: failure
gs_wlm_switch_cgroup(pid int, cgroup text)
Description: Moves a job to another Cgroup to change the job priority.

Return type: Boolean
- true: success
- false: failure
pv_session_memctx_detail(threadid tid, MemoryContextName text)
Description: Records information about the memory context MemoryContextName of the thread tid into the threadid_timestamp.log file in the $GAUSSLOG/pg_log/${node_name}/dumpmem directory. threadid can be obtained from sessid in the GS_SESSION_MEMORY_DETAIL view. In the officially released version, only the MemoryContextName that is an empty string (two single quotation marks indicate that the input is an empty string) is accepted. In this case, all memory context information is recorded. Otherwise, no operation is performed. For the DEBUG version for internal development and test personnel to debug, you can specify the MemoryContextName to be counted. In this case, all the memory usage of the context is recorded in the specified file. Only the administrator can execute this function.

Return type: Boolean
- true: success
- false: failure
pg_shared_memctx_detail(MemoryContextName text)
Description: Records information about the memory context MemoryContextName into the threadid_timestamp.log file in the $GAUSSLOG/pg_log/${node_name}/dumpmem directory. This function is provided only for internal development and test personnel to debug in the DEBUG version. Calling this function in the officially released version does not involve any operation. Only the administrator can execute this function.

Return type: Boolean
- true: success
- false: failure
local_bgwriter_stat()
Description: Displays the information about pages flushed by the bgwriter thread of this instance, number of pages in the candidate buffer chain, and buffer elimination information.

Return type: record
local_candidate_stat()
Description: Displays the number of pages in the candidate buffer chain of this instance and buffer elimination information, including the normal buffer pool and segment buffer pool.

Return type: record
local_ckpt_stat()
Description: Displays the information about checkpoints and flushing pages of the current instance.

Return type: record

local_double_write_stat()

Description: Displays the doublewrite file status of the current instance.

Return type: record

**Table 3** local_double_write_stat parameters
Parameter	Type	Description
node_name	text	Instance name
curr_dwn	int8	Sequence number of the doublewrite file
curr_start_page	int8	Start page for restoring the doublewrite file
file_trunc_num	int8	Number of times that the doublewrite file is reused
file_reset_num	int8	Number of reset times after the doublewrite file is full
total_writes	int8	Total number of I/Os of the doublewrite file
low_threshold_writes	int8	Number of I/Os for writing doublewrite files with low efficiency (the number of I/O flushing pages at a time is less than 16)
high_threshold_writes	int8	Number of I/Os for writing doublewrite files with high efficiency (the number of I/O flushing pages at a time is more than 421)
total_pages	int8	Total number of pages that are flushed to the doublewrite file area
low_threshold_pages	int8	Number of pages that are flushed with low efficiency
high_threshold_pages	int8	Number of pages that are flushed with high efficiency
file_id	int8	ID of the current doublewrite file

local_single_flush_dw_stat()
Description: Displays the elimination of dual-write files on a single page in the instance.

Return type: record
local_pagewriter_stat()
Description: Displays the page flushing information and checkpoint information of the current instance.

Return type: record
local_redo_stat()
Description: Displays the replay status of the current standby instance.

Return type: record

Note: The returned replay status includes the current replay position and the replay position of the minimum restoration point.
local_recovery_status()
Description: Displays log flow control information about the primary and standby nodes.

Return type: record
gs_wlm_node_recover(boolean isForce)

Description: Obtains top SQL query statement-level statistics recorded in the current memory. If the input parameter is not 0, the information is cleared from the memory.

Return type: record
gs_wlm_node_clean(cstring nodename)
Description: Clears data after the dynamic load management node is faulty. (The current feature is a lab feature. Contact Huawei technical support before using it.) Only administrators can execute this function. This function is called by the database instance management module. You are not advised to directly call this function. This view is not supported in a centralized or standalone system.

Return type: Boolean
gs_cgroup_map_ng_conf(group name)
Description: Reads the Cgroup configuration file of a specified logical database.

Return type: record
gs_wlm_switch_cgroup(sess_id int8, cgroup name)
Description: Switches the Cgroup of a specified session.

Return type: record
comm_client_info()
Description: Queries information about active client connections of a single node.

Return type: SETOF record
pg_sync_cstore_delta(text)
Description: Synchronizes the delta table structure of a specified column-store table with that of the column-store primary table.

Return type: bigint
pg_sync_cstore_delta()
Description: Synchronizes the delta table structure of all column-store tables with that of the column-store primary table.

Return type: bigint
pg_get_flush_lsn()
Description: Returns the position of the Xlog flushed from the current node.

Return type: text
pg_get_sync_flush_lsn()
Description: Returns the position of the Xlog flushed by the majority on the current node.

Return type: text
gs_create_log_tables()
Description: Creates foreign tables and views for run logs and performance logs. (The current feature is a lab feature. Contact Huawei technical support before using it.)

Return type: void

Example:
```
openGauss=# select gs_create_log_tables();
 gs_create_log_tables
----------------------

(1 row)
```

dbe_perf.get_global_full_sql_by_timestamp(start_timestamp timestamp with time zone, end_timestamp timestamp with time zone)

Description: Obtains full SQL information at the database level. The result can be queried only in the system database but cannot be queried in the user database.

Return type: record

**Table 4** dbe_perf.get_global_full_sql_by_timestamp parameter description
Parameter	Type	Description
start_timestamp	timestamp with time zone	Start point of the SQL start time range.
end_timestamp	timestamp with time zone	End point of the SQL start time range.

dbe_perf.get_global_slow_sql_by_timestamp(start_timestamp timestamp with time zone, end_timestamp timestamp with time zone)

Description: Obtains slow SQL information at the database level. The result can be queried only in the system database but cannot be queried in the user database.

Return type: record

**Table 5** dbe_perf.get_global_slow_sql_by_timestamp parameter description
Parameter	Type	Description
start_timestamp	timestamp with time zone	Start point of the SQL start time range.
end_timestamp	timestamp with time zone	End point of the SQL start time range.

statement_detail_decode(detail text, format text, pretty boolean)

Description: Parses the details column in a full or slow SQL statement. The result can be queried only in the system database but cannot be queried in the user database.

Return type: text

**Table 6** statement_detail_decode parameter description
Parameter	Type	Description
detail	text	Set of events generated by the SQL statement (unreadable).
format	text	Parsing output format. The value is plaintext.
pretty	boolean	Whether to display the text in pretty format when format is set to plaintext. The options are as follows: The value true indicates that events are separated by \n. The value false indicates that events are separated by commas (,).

pg_control_system()
Description: Returns the status of the system control file.

Return type: SETOF record
pg_control_checkpoint()
Description: Returns the system checkpoint status.

Return type: SETOF record
get_prepared_pending_xid
Description: Returns nextxid when restoration is complete.

Parameter: nan

Return type: text
pg_clean_region_info
Description: Clears the regionmap.

Parameter: nan

Return type: character varying
pg_get_delta_info
Description: Obtains delta information from a single DN.

Parameter: rel text, schema_name text

Return type: part_name text, live_tuple bigint, data_size bigint, and blocknum bigint
pg_get_replication_slot_name
Description: Obtains the slot name.

Parameter: nan

Return type: text
pg_get_running_xacts
Description: Obtains running xact.

Parameter: nan

Return type: handle integer, gxid xid, state tinyint, node text, xmin xid, vacuum boolean, timeline bigint, prepare_xid xid, pid bigint, and next_xid xid
pg_get_variable_info
Description: Obtains the shared memory variable cache.

Parameter: nan

Return type: node_name text, nextOid oid, nextXid xid, oldestXid xid, xidVacLimit xid, oldestXidDB oid, lastExtendCSNLogpage xid, startExtendCSNLogpage xid, nextCommitSeqNo xid, latestCompletedXid xid, and startupMaxXid xid
pg_get_xidlimit
Description: Obtains transaction ID information from the shared memory.

Parameter: nan

Return type: nextXid xid, oldestXid xid, xidVacLimit xid, xidWarnLimit xid, xidStopLimit xid, xidWrapLimit xid, and oldestXidDB oid
pg_relation_compression_ratio
Description: Queries the compression rate of a table. By default, 1.0 is returned.

Parameter: text

Return type: real
pg_relation_with_compression
Description: Queries whether a table is compressed.

Parameter: text

Return type: Boolean
pg_stat_file_recursive
Description: Lists all files in the path.

Parameter: location text

Return type: path text, filename text, size bigint, and isdir boolean
pg_stat_get_activity_for_temptable
Description: Returns records of backend processes related to the temporary table.

Parameter: nan

Return type: datid oid, timelineid integer, tempid integer, and sessionid bigint
pg_stat_get_activity_ng
Description: Returns records of backend processes related to nodegroup.

Parameter: pid bigint

Return type: datid oid, pid bigint, sessionid bigint, and node_group text
pg_stat_get_cgroup_info
Description: Returns Cgroup information.

Parameter: nan

Return type: cgroup_name text, percent integer, usage_percent integer, shares bigint, usage bigint, cpuset text, relpath text, valid text, and node_group text
pg_stat_get_realtime_info_internal
Description: Returns real-time information. Currently, this API is unavailable. FailedToGetSessionInfo is returned.

Parameter: oid, oid, bigint, cstring, oid

Return type: text
pg_stat_get_workload_struct_info
Description: Returns the load management data structure. (The current feature is a lab feature. Contact Huawei technical support before using it.)

Parameter: nan

Return type: text
pg_test_err_contain_err
Description: Tests the error type and return information.

Parameter: integer

Return type: void
get_global_user_transaction()
Description: Returns transaction information about each user on all nodes.

Return type: node_name name, usename name, commit_counter bigint, rollback_counter bigint, resp_min bigint, resp_max bigint, resp_avg bigint, resp_total bigint, bg_commit_counter bigint, bg_rollback_counter bigint, bg_resp_min bigint, bg_resp_max bigint, bg_resp_avg bigint, and bg_resp_total bigint
pg_collation_for
Description: Returns the sorting rule corresponding to the input parameter string.

Parameter: any (Explicit type conversion is required for constants.)

Return type: text
pgxc_unlock_for_sp_database(name Name)
Description: Releases a specified database lock.

Parameter: database name

Return type: Boolean
pgxc_lock_for_sp_database(name Name)
Description: Locks a specified database.

Parameter: database name

Return type: Boolean

copy_error_log_create()

Description: Creates the error table (public.pgxc_copy_error_log) required for creating the COPY FROM error tolerance mechanism.

Return type: Boolean

This function attempts to create the public.pgxc_copy_error_log table. For details about the table, see Table 7.
In addition, it creates a B-tree index on the relname column and executes REVOKE ALL on public.pgxc_copy_error_log FROM public to manage permissions on the error table (the permissions are the same as those of the COPY statement).
public.pgxc_copy_error_log is a row-store table. Therefore, this function can be executed and COPY error tolerance is available only when row-store tables can be created in the database instance. Note that after the GUC parameter enable_hadoop_env is enabled, row-store tables cannot be created in the database instance (the default value is off for GaussDB).
Same as the error table and the COPY statement, the function requires sysadmin or higher permissions.
If the public.pgxc_copy_error_log table or the copy_error_log_relname_idx index exists before the function creates it, the function will report an error and roll back.

**Table 7** Error table public.pgxc_copy_error_log
Column	Type	Description
relname	character varying	Table name in the form of Schema name.Table name
begintime	timestamp with time zone	Time when a data format error was reported
filename	character varying	Name of the source data file where a data format error occurs
lineno	bigint	Number of the row where a data format error occurs in a source data file
rawrecord	text	Raw record of a data format error in the source data file
detail	text	Error details

dynamic_func_control(scope text, function_name text, action text, "{params}" text[])

Description: Dynamically enables built-in functions. Currently, only full SQL statements can be dynamically enabled.

Return type: record

**Table 8** Parameter description of dynamic_func_control
Parameter	Type	Description
scope	text	Scope where the function is to be dynamically enabled. Currently, only LOCAL is supported.
function_name	text	Function name. Currently, only STMT is supported.
action	text	When function_name is set to STMT, the value of action can only be TRACK, UNTRACK, LIST, or CLEAN. TRACK: records the full SQL information of normalized SQL statements. UNTRACK: cancels the recording of full SQL information of normalized SQL statements. LIST: lists normalized SQL information that is recorded in the current track. CLEAN: cleans normalized SQL information that is recorded in the current track.
params	text[]	When function_name is set to STMT, the parameters corresponding to different actions are set as follows: TRACK: '{"Normalized SQLID", "L0/L1/L2"}' UNTRACK: '{"Normalized SQLID"}' LIST - '{}' CLEAN - '{}'

gs_parse_page_bypath(path text, blocknum bigint, relation_type text, read_memory boolean)

Description: Parses a specified table page and returns the path for storing the parsed content.

Return type: text

Note: Only the system administrator or O&M administrator can execute this function.

**Table 9** gs_parse_page_bypath parameters
Parameter	Type	Description
path	text	For an ordinary table or segment-page table, the relative path is Tablespace name/Database OID/Relfilenode of the table (physical file name). For example, base/16603/16394. You can run the pg_relation_filepath(table_name text) command to query the relative path of the table file. To obtain the path of the partitioned table, view the pg_partition system catalog and call pg_partition_filepath(partition_oid). Valid path formats are as follows: global/relNode base/dbNode/relNode pg_tblspc/spcNode/version_dir/dbNode/relNode
blocknum	bigint	–1: Information about all blocks (forcibly parsed from disks) 0–MaxBlockNumber: Information about the corresponding block
relation_type	text	heap: Astore table uheap: Ustore table btree: B-tree index ubtree: UB-tree index segment: Segment-page table indexurq: Ustore recycling queue
read_memory	boolean	false: The system parses the page from the disk file. true: The system attempts to parse the page from the shared buffer. If the page does not exist in the shared buffer, the system parses the page from the disk file.

gs_xlogdump_lsn(start_lsn text, end_lsn text)

Description: Parses Xlogs within the specified LSN range and returns the path for storing the parsed content. You can use pg_current_xlog_location() to obtain the current Xlog position.

Return type: text

Parameters: LSN start position and LSN end position

Note: Only the system administrator or O&M administrator can execute this function.
gs_xlogdump_xid(c_xid xid)

Description: Parses Xlogs of a specified XID and returns the path for storing the parsed content. You can use txid_current() to obtain the current transaction ID.

Parameter: transaction ID

Return type: text

Note: Only the system administrator or O&M administrator can execute this function.

gs_xlogdump_tablepath(path text, blocknum bigint, relation_type text)

Description: Parses logs corresponding to a specified table page and returns the path for storing the parsed content.

Return type: text

Note: Only the system administrator or O&M administrator can execute this function.

**Table 10** gs_xlogdump_tablepath parameters
Parameter	Type	Description
path	text	For an ordinary table or segment-page table, the relative path is Tablespace name/Database OID/Relfilenode of the table (physical file name). For example, base/16603/16394. You can run the pg_relation_filepath(table_name text) command to query the relative path of the table file. To obtain the path of the partitioned table, view the pg_partition system catalog and call pg_partition_filepath(partition_oid). Valid path formats are as follows: global/relNode base/dbNode/relNode pg_tblspc/spcNode/version_dir/dbNode/relNode
blocknum	bigint	–1: Information about all blocks (forcibly parsed from disks) 0–MaxBlockNumber: Information about the corresponding block
relation_type	text	heap: Astore table uheap: Ustore table btree: B-tree index ubtree: UB-tree index segment: Segment-page table indexurq: Ustore recycling queue

gs_xlogdump_parsepage_tablepath(path text, blocknum bigint, relation_type text, read_memory boolean)

Description: Parses the specified table page and logs corresponding to the table page and returns the path for storing the parsed content. It can be regarded as one execution of gs_parse_page_bypath and gs_xlogdump_tablepath. The prerequisite for executing this function is that the table file exists. To view logs of deleted tables, call gs_xlogdump_tablepath.

Return type: text

Note: Only the system administrator or O&M administrator can execute this function.

**Table 11** gs_xlogdump_parsepage_tablepath parameters
Parameter	Type	Description
path	text	For an ordinary table or segment-page table, the relative path is Tablespace name/Database OID/Relfilenode of the table (physical file name). For example, base/16603/16394. You can run the pg_relation_filepath(table_name text) command to query the relative path of the table file. To obtain the path of the partitioned table, view the pg_partition system catalog and call pg_partition_filepath(partition_oid). Valid path formats are as follows: global/relNode base/dbNode/relNode pg_tblspc/spcNode/version_dir/dbNode/relNode
blocknum	bigint	–1: Information about all blocks (forcibly parsed from disks) 0–MaxBlockNumber: Information about the corresponding block
relation_type	text	heap: Astore table uheap: Ustore table btree: B-tree index ubtree: UB-tree index segment: Segment-page table indexurq: Ustore recycling queue
read_memory	boolean	false: The system parses the page from the disk file. true: The system attempts to parse the page from the shared buffer. If the page does not exist in the shared buffer, the system parses the page from the disk file.

gs_index_verify(Oid oid, uint32 blkno)

Description: Checks whether the sequence of keys on the UB-tree index page or index tree is correct.

Return type: record

**Table 12** gs_index_verify parameters
Parameter	Type	Description
oid	Oid	Index file relfilenode, which can be queried using select relfilenode from pg_class where relname='Index file name'.
blkno	uint32	0: indicates that all pages in the index tree are checked. If the value is greater than 0, the index page whose page code is equal to the value of blkno is checked.

gs_index_recycle_queue(Oid oid, int type, uint32 blkno)

Description: Parses the UB-tree index recycling queue information.

Return type: record

**Table 13** gs_index_recycle_queue parameters
Parameter	Type	Description
oid	Oid	Index file relfilenode, which can be queried using select relfilenode from pg_class where relname='Index file name'.
type	int	0: indicates that the entire queue to be recycled is parsed. 1: indicates that the entire empty page queue is parsed. 2: indicates that a single page is parsed.
blkno	uint32	ID of the recycling queue page. This parameter is valid only when type is set to 2. The value of blkno ranges from 1 to 4294967294.

gs_stat_wal_entrytable(int64 idx)

Description: Exports the content of the write-ahead log insertion status table in the Xlog.

Return type: record

**Table 14** gs_stat_wal_entrytable parameters
Category	Parameter	Type	Description
Input parameter	idx	int64	–1: queries all elements in an array. 0-Maximum value: content of a specific array element.
Output parameter	idx	uint64	Records the subscripts in the corresponding array.
Output parameter	endlsn	uint64	Records the LSN label.
Output parameter	lrc	int32	Records the corresponding LRC.
Output parameter	status	uint32	Determines whether the Xlog corresponding to the current entry has been completely copied to the WAL buffer: 0: Not copied. 1: Copied

gs_walwriter_flush_position()

Description: Outputs the refresh position of write-ahead logs.

Return type: record

**Table 15** gs_walwriter_flush_position parameters
Category	Parameter	Type	Description
Output parameter	last_flush_status_entry	int32	Subscript index obtained after the Xlog flushes the tblEntry of the last flushed disk.
Output parameter	last_scanned_lrc	int32	LRC obtained after the Xlog flushes the last tblEntry scanned last time.
Output parameter	curr_lrc	int32	Latest LRC usage in the WALInsertStatusEntry status table. The LRC indicates the LRC value corresponding to the WALInsertStatusEntry when the next Xlog record is written.
Output parameter	curr_byte_pos	uint64	The latest Xlog position after the Xlog is written to the WAL file, which is also the next Xlog insertion point.
Output parameter	prev_byte_size	uint32	Length of the previous Xlog record.
Output parameter	flush_result	uint64	Position of the current global Xlog flush.
Output parameter	send_result	uint64	Xlog sending position on the current host.
Output parameter	shm_rqst_write_pos	uint64	The write position of the LogwrtRqst request in the XLogCtl recorded in the shared memory.
Output parameter	shm_rqst_flush_pos	uint64	The flush position of the LogwrtRqst request in the XLogCtl recorded in the shared memory.
Output parameter	shm_result_write_pos	uint64	The write position of the LogwrtResult request in the XLogCtl recorded in the shared memory.
Output parameter	shm_result_flush_pos	uint64	The flush position of the LogwrtResult request in the XLogCtl recorded in the shared memory.
Output parameter	curr_time	text	Current time.

gs_walwriter_flush_stat(int operation)

Description: Collects statistics on the frequency of writing and synchronizing write-ahead logs, data volume, and Xlog file information.

Return type: record

**Table 16** gs_walwriter_flush_stat parameters
Category	Parameter	Type	Description
Input parameter	operation	int	–1: Disables the statistics function. (Default value) 0: Enable the statistics function. 1: Query statistics. 2: Reset statistics.
Output parameter	write_times	uint64	Number of times that the Xlog calls the write API.
Output parameter	sync_times	uint64	Number of times that the Xlog calls the sync API.
Output parameter	total_xlog_sync_bytes	uint64	Total number of backend thread requests for writing data to Xlogs.
Output parameter	total_actual_xlog_sync_bytes	uint64	Total number of Xlogs that call the sync API for disk flushing.
Output parameter	avg_write_bytes	uint32	Number of Xlogs written each time the XLogWrite API is called.
Output parameter	avg_actual_write_bytes	uint32	Number of Xlogs written each time the write API is called.
Output parameter	avg_sync_bytes	uint32	Average number of Xlogs for each synchronization request.
Output parameter	avg_actual_sync_bytes	uint32	Actual Xlog amount of disk flushing by calling sync each time.
Output parameter	total_write_time	uint64	Total time of calling the write operation (unit: μs).
Output parameter	total_sync_time	uint64	Total time for calling the sync API (unit: μs).
Output parameter	avg_write_time	uint32	Average time for calling the write API each time (unit: μs).
Output parameter	avg_sync_time	uint32	Average time for calling the sync API each time (unit: μs).
Output parameter	curr_init_xlog_segno	uint64	ID of the latest Xlog segment file.
Output parameter	curr_open_xlog_segno	uint64	ID of the Xlog segment file that is being written.
Output parameter	last_reset_time	text	Time when statistics were last collected.
Output parameter	curr_time	text	Current time.

gs_catalog_attribute_records()
Description: Returns the definition of each field in a specified system catalog. Only common system catalogs whose OIDs are less than 10000 are supported. Indexes and TOAST tables are not supported.

Parameter: OID of the system catalog

Return type: record
gs_comm_proxy_thread_status()
Description: Collects statistics on data packets sent and received by the proxy communication library comm_proxy when a user-mode network is configured for the database instance.

Parameter: nan

Return type: record

The query result of this function is displayed only when the user-mode network is deployed in a centralized environment and enable_dfx in comm_proxy_attr is set to true. In other scenarios, an error message is displayed, indicating that queries are not supported.

pg_ls_tmpdir()

Description: Returns the name, size, and last modification time of each file in the temporary directory (pgsql_tmp) of the default tablespace.

Parameter: nan

Return type: record

Note: Only the system administrator or monitor administrator can execute this function.

Category	Parameter	Type	Description
Output parameter	name	text	File name
Output parameter	size	int8	File size (unit: byte)
Output parameter	modification	timestamptz	Last file modification time

pg_ls_tmpdir(oid)

Description: Returns the name, size, and last modification time of each file in the temporary directory (pgsql_tmp) of the specified tablespace.

Parameter: oid

Return type: record

Note: Only the system administrator or monitor administrator can execute this function.

Category	Parameter	Type	Description
Input parameter	oid	oid	Tablespace ID
Output parameter	name	text	File name
Output parameter	size	int8	File size (unit: byte)
Output parameter	modification	timestamptz	Last file modification time

pg_ls_waldir()

Description: Returns the name, size, and last modification time of each file in the WAL directory.

Parameter: nan

Return type: record

Note: Only the system administrator or monitor administrator can execute this function.

Category	Parameter	Type	Description
Output parameter	name	text	File name
Output parameter	size	int8	File size (unit: byte)
Output parameter	modification	timestamptz	Last file modification time

gs_write_term_log(void)
Description: Writes a log to record the current term value of a DN. The standby DN returns false. After the data is successfully written to the primary DN, true is returned.

Return type: Boolean