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 Procedural SQL (PSQL) StatementsAggregate Functions 

Unless explicitly mentioned otherwise in an “Available in” section, functions are available in DSQL and PSQL.Availability of built-in functions in ESQL is not tracked by this Language Reference.

Context Functions

RDB$GET_CONTEXT()

Retrieves the value of a context variable from a namespace

Result type

VARCHAR(255)

Syntax
RDB$GET_CONTEXT ('<namespace>', <varname>)

<namespace> ::= SYSTEM | USER_SESSION | USER_TRANSACTION | DDL_TRIGGER
<varname>   ::= A case-sensitive quoted string of max. 80 characters
Table 1. RDB$GET_CONTEXT Function Parameters
Parameter Description

namespace

Namespace

varname

Variable name;case-sensitive with a maximum length of 80 characters
The namespaces

The USER_SESSION and USER_TRANSACTION namespaces are initially empty.A user can create and set variables with RDB$SET_CONTEXT() and retrieve them with RDB$GET_CONTEXT().The SYSTEM namespace is read-only.The DDL_TRIGGER namespace is only valid in DDL triggers, and is read-only.The SYSTEM and DDL_TRIGGER namespaces contain a number of predefined variables, shown below.

Return values and error behaviour

If the polled variable exists in the given namespace, its value will be returned as a string of max. 255 characters.If the namespace doesn’t exist or if you try to access a non-existing variable in the SYSTEM or DDL_TRIGGER namespace, an error is raised.If you request a non-existing variable in one of the user namespaces, NULL is returned.Both namespace and variable names must be given as single-quoted, case-sensitive, non-NULL strings.

The SYSTEM Namespace

Context variables in the SYSTEM namespace
CLIENT_ADDRESS

For TCP, this is the IP address.For XNET, the local process ID.For all other protocols this variable is NULL.

CLIENT_HOST

The wire protocol host name of remote client.Value is returned for all supported protocols.

CLIENT_PID

Process ID of remote client application.

CLIENT_PROCESS

Process name of remote client application.

CURRENT_ROLE

Same as global [fblangref50-contextvars-current-role] variable.

CURRENT_USER

Same as global [fblangref50-contextvars-current-user] variable.

DB_FILE_ID

Unique filesystem-level ID of the current database.

DB_GUID

GUID of the current database.

DB_NAME

Canonical name of current database;either the full path to the database or — if connecting via the path is disallowed — its alias.

DECFLOAT_ROUND

Rounding mode of the current connection used in operations with DECFLOAT values.See also SET DECFLOAT.

DECFLOAT_TRAPS

Exceptional conditions for the current connection in operations with DECFLOAT values that cause a trap.See also SET DECFLOAT.

EFFECTIVE_USER

Effective user at the point RDB$GET_CONTEXT is called;indicates privileges of which user is currently used to execute a function, procedure, trigger.

ENGINE_VERSION

The Firebird engine (server) version.

EXT_CONN_POOL_ACTIVE_COUNT

Count of active connections associated with the external connection pool.

EXT_CONN_POOL_IDLE_COUNT

Count of currently inactive connections available in the connection pool.

EXT_CONN_POOL_LIFETIME

External connection pool idle connection lifetime, in seconds.

EXT_CONN_POOL_SIZE

External connection pool size.

GLOBAL_CN

Most current value of global Commit Number counter.

ISOLATION_LEVEL

The isolation level of the current transaction: 'READ COMMITTED', 'SNAPSHOT' or 'CONSISTENCY'.

LOCK_TIMEOUT

Lock timeout of the current transaction.

NETWORK_PROTOCOL

The protocol used for the connection: 'TCPv4', 'TCPv6', 'XNET' or NULL.

PARALLEL_WORKERS

The maximum number of parallel workers of the connection.

READ_ONLY

Returns 'TRUE' if current transaction is read-only and 'FALSE' otherwise.

REPLICA_MODE

Replica mode of the database: 'READ-ONLY', 'READ-WRITE' and NULL.

REPLICATION_SEQUENCE

Current replication sequence (number of the latest segment written to the replication journal).

SESSION_ID

Same as global [fblangref50-contextvars-current-connection] variable.

SESSION_IDLE_TIMEOUT

Connection-level idle timeout, or 0 if no timeout was set.When 0 is reported the database ConnectionIdleTimeout from databases.conf or firebird.conf applies.

SESSION_TIMEZONE

Current session time zone.

SNAPSHOT_NUMBER

Current snapshot number for the transaction executing this statement.For SNAPSHOT and SNAPSHOT TABLE STABILITY, this number is stable for the duration of the transaction;for READ COMMITTED this number will change (increment) as concurrent transactions are committed.

STATEMENT_TIMEOUT

Connection-level statement timeout, or 0 if no timeout was set.When 0 is reported the database StatementTimeout from databases.conf or firebird.conf applies.

TRANSACTION_ID

Same as global [fblangref50-contextvars-current-transaction] variable.

WIRE_COMPRESSED

Compression status of the current connection.If the connection is compressed, returns TRUE;if it is not compressed, returns FALSE.Returns NULL if the connection is embedded.

WIRE_CRYPT_PLUGIN

If connection is encrypted - returns name of current plugin, otherwise NULL.

WIRE_ENCRYPTED

Encryption status of the current connection.If the connection is encrypted, returns TRUE;if it is not encrypted, returns FALSE.Returns NULL if the connection is embedded.