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 the sysadmin and monitor admin users can access the environment variable information.

  Return type: record

  Example:

  mogdb=# select pg_stat_get_env();
                                                                                pg_stat_get_env
  ---------------------------------------------------------------------------------------------------------------------------------------
   (coordinator1,localhost,144773,49100,/data1/MogDB_Kernel_TRUNK/install,/data1/MogDB_Kernel_TRUNK/install/data/coordinator1,pg_log)
  (1 row)

• pg_catalog.plancache_clean()

  Description: Clears the global plan cache that is not used on nodes.

  Return type: bool

• 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()

  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 session status stored in the memory of the current node.

  Return type: record

• pg_stat_get_thread()

  Description: Provides information about the status of all threads under the current node.

  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.

  Return type: record

• pg_stat_get_data_senders()

  Description: Provides detailed information about the data-copy sending thread active at the moment.

  Return type: record

• generate_wdr_report(begin_snap_id Oid, end_snap_id Oid, int report_type, int report_scope, int node_name)

  Description: Generates system diagnosis reports based on two snapshots.

  Return type: record

  Table 1 generate_wdr_report parameter description

  Parameter	Description	Value Range
  begin_snap_id	Snapshot ID that starts the diagnosis report period.	-
  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.	-
  report_type	Specifies the type of the generated report.	summarydetailall: Both summary and detail types are included.
  report_scope	Specifies the scope for a report to be generated.	node: a node in MogDB
  node_name	When report_scope is set to node, set this parameter to the name of the corresponding node.	-

• create_wdr_snapshot(stat text, dbid Oid)

  Description: Manually generates system diagnosis snapshots.

  Return type: record

• reset_unique_sql

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

  Return type: bool

  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': The Unique SQL statements are cleared based on user IDs.'BY_CNID': The 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 cross-database queries at local. 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 primary database node queue.

  Return type: Boolean

  • true: success
  • false: failure

• gs_wlm_switch_cgroup(pid int, cgroup text)

  Description: Moves a job to other Cgroup to improve the job priority.

  Return type: Boolean

  • true: success
  • false: failure

• pv_session_memctx_detail(threadid tid, MemoryContextName text)

  Description: Record 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 PV_SESSION_MEMORY_DETAILtable. In the officially released version, only theMemoryContextNamethat 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 theMemoryContextName 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: Record 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_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

• 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 instances.

  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_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 control group of a specified session.

  Return type: record

• hdfs_fdw_handler()

  Description: Rewrites a foreign table. It is a function to be defined when a foreign table is defined.

  Return type: record

• hdfs_fdw_validator(text[], oid)

  Description: Rewrites a foreign table. It is a function to be defined when a foreign table is defined.

  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 location of the Xlog flushed from the current node.

  Return type: text

• pg_get_sync_flush_lsn()

  Description: Returns the location 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.

  Return type: void

  Example:

  mogdb=# 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.

  Return type: record

  Table 3 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.

  Return type: record

  Table 4 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.

  Return type: text

  Table 5 statement_detail_decode parameter description

  Parameter	Type	Description
  detail	text	A 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 (,).

• 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, 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

  NOTE:

  • This function attempts to create the public.pgxc_copy_error_log table. For details about the table, see Table 6.
  • Create the B-tree index on the relname column and execute REVOKE ALL on public.pgxc_copy_error_log FROM public to manage permissions for 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 of MogDB is off).
  • 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 6 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