Session information functions supported by Hologres - Hologres

Hologres is compatible with PostgreSQL and allows you to use the standard PostgreSQL syntax to develop data.

The following table describes the session information functions supported by Hologres. The functions supported by Hologres are only a subset of the PostgreSQL functions. For more information about how to use these functions, see System Information Functions in the PostgreSQL documentation.

Function	Description
CURRENT_CATALOG	Returns the name of the current catalog.
CURRENT_DATABASE	Returns the name of the current database.
CURRENT_QUERY	Returns the query statement that is being executed.
CURRENT_ROLE	Returns the ID of the account that is being used to perform operations on the database.
CURRENT_SCHEMA	Returns the name of the current schema.
CURRENT_SCHEMAS	Returns an array of the names of all available schemas in the current search path.
CURRENT_USER	Returns the ID of the current account.
INET_CLIENT_ADDR	Returns the remote connection address of the current user.
INET_CLIENT_PORT	Returns the remote connection port of the current user.
INET_SERVER_ADDR	Returns the IP address of the current server.
INET_SERVER_PORT	Returns the port number of the current server.
PG_BACKEND_PID	Returns the ID of the server process to which the current session belongs.
PG_BLOCKING_PIDS	Returns the ID of the process that is blocking the specified server process ID from acquiring a lock.
SESSION_USER	Returns the account ID of the user for the current session.
USER	Returns the account ID of the current logon user.
VERSION	Returns the version of PostgreSQL.

CURRENT_CATALOG

Description: Returns the name of the current catalog.
```
CURRENT_CATALOG
```
Return value:
The name of the current catalog is returned.

Example:

SELECT CURRENT_CATALOG;

The following result is returned:

 current_catalog
-----------------
 hologrestest

CURRENT_DATABASE

Description: Returns the name of the current database.
```
CURRENT_DATABASE()
```
Return value:
The name of the current database is returned.

Example:

SELECT CURRENT_DATABASE();

The following result is returned:

 current_database
------------------
 hologrestest

CURRENT_QUERY

Description: Returns the query statement that is being executed.
```
CURRENT_QUERY()
```
Return value:
The query statement that is being executed is returned.

Example:

SELECT CURRENT_QUERY();

The following result is returned:

      current_query
-------------------------
 SELECT CURRENT_QUERY();

CURRENT_ROLE

Description: Returns the ID of the account that is being used to perform operations on the database.
```
CURRENT_ROLE
```
Return value:
The ID of the account that is being used to perform operations on the database is returned.

Example:

SELECT CURRENT_ROLE;

The following result is returned:

   current_role
------------------
 139699392458****

CURRENT_SCHEMA

Description: Returns the name of the current schema.
```
CURRENT_SCHEMA[()]
```
Return value:
The name of the current schema is returned.

Example:

SELECT CURRENT_SCHEMA();

The following result is returned:

 current_schema
----------------
 public

CURRENT_SCHEMAS

Description: Returns an array of the names of all available schemas in the current search path.
```
CURRENT_SCHEMAS(FLAG)
```
Parameters:
FLAG: specifies whether implicit schemas, such as pg_catalog, are included in the returned schemas. Valid values: TRUE and FALSE.
Return value:
An array of the names of all available schemas in the current search path is returned.
- If the FLAG parameter is set to TRUE, implicit schemas, such as pg_catalog, are included in the returned schemas.
- If the FLAG parameter is set to FALSE, implicit schemas, such as pg_catalog, are not included in the returned schemas.

Examples:

Example 1:

SELECT CURRENT_SCHEMAS(TRUE);

The following result is returned:

   current_schemas
---------------------
 {pg_catalog,public}

Example 2:

SELECT CURRENT_SCHEMAS(FALSE);

The following result is returned:

   current_schemas
---------------------
 {public}

CURRENT_USER

Description: Returns the ID of the current account.
```
CURRENT_USER
```
Return value:
The ID of the current account is returned.

Example:

SELECT CURRENT_USER;

The following result is returned:

   current_user
------------------
 139699392458****

INET_CLIENT_ADDR

Description: Returns the remote connection address of the current user.
```
INET_CLIENT_ADDR()
```
Return value:
The remote connection address of the current user is returned.

Example:

SELECT INET_CLIENT_ADDR();

The following result is returned:

inet_client_addr
------------------
 124.8*.1**.1**

INET_CLIENT_PORT

Description: Returns the remote connection port of the current user.
```
INET_CLIENT_PORT()
```
Return value:
The remote connection port of the current user is returned.

Example:

SELECT INET_CLIENT_PORT();

The following result is returned:

inet_client_port
------------------
             5823

INET_SERVER_ADDR

Description: Returns the IP address of the current server.
```
INET_SERVER_ADDR()
```
Return value: The IP address of the current server is returned.

Example:

SELECT INET_SERVER_ADDR();

The following result is returned:

 inet_server_addr
------------------
 10.**.4*.4*

INET_SERVER_PORT

Description: Returns the port number of the current server.
```
INET_SERVER_PORT()
```
Return value:
The port number of the current server is returned.

Example:

SELECT INET_SERVER_PORT();

The following result is returned:

 inet_server_port
------------------
            42581

PG_BACKEND_PID

Description: Returns the ID of the server process to which the current session belongs.
```
PG_BACKEND_PID()
```
Return value:
The ID of the server process to which the current session belongs is returned.

Example:

SELECT PG_BACKEND_PID();

The following result is returned:

 pg_backend_pid
----------------
       53674002

PG_BLOCKING_PIDS

Description: Returns the ID of the process that is blocking the specified server process ID from acquiring a lock.
```
PG_BLOCKING_PIDS(INT)
```
Return value: The ID of the process that is blocking the specified server process ID from acquiring a lock is returned.

Example:

SELECT PG_BLOCKING_PIDS(1);

The following result is returned:

 pg_blocking_pids
------------------
 {}

SESSION_USER

Description: Returns the account ID of the user for the current session.
```
SESSION_USER
```
Return value:
The account ID of the user for the current session is returned.

Example:

SELECT SESSION_USER;

The following result is returned:

   session_user
------------------
 139699392458****

USER

Description: Returns the account ID of the current logon user.
```
USER
```
Return value: The account ID of the current logon user is returned.

Example:

SELECT USER;

The following result is returned:

       user
------------------
 139699392458****

VERSION

Description: Returns the version of PostgreSQL.
```
VERSION()
```
Return value: The version of PostgreSQL is returned.

Example:

SELECT VERSION();

The following result is returned:

                                                                                               version                  
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 PostgreSQL 11.3 (Release-build@6feee25dff7 on release-3.0.x) on x86_64-linux, compiled by clang version 13.0.1 (Alibaba 13.0.1-2.fix20240305102602.alios7 193811f571966bccce929b0f457df345c4fca5ed)