year  Chapter 4: Expressions, Identifiers, and Wildcard Characters


Chapter 3: Global Variables


Adaptive Server global variables

Global variables are system-defined variables updated by Adaptive Server while the system is running. Some global variables are session-specific, while others are server instance-specific. For example, @@error contains the last error number generated by the system for a given user connection.

See get_appcontext and set_appcontext to specify application context variables.

To view the value for any global variable, enter:

select variable_name

For example:

select @@char_convert

Table 3-1lists the global variables available for Adaptive Server:

Table 3-1: Adaptive Server global variables

Global variable

Definition

@@authmech

A read-only variable that indicates the mechanism used to authenticate the user.

@@bootcount

Returns the number of times an Adaptive Server installation has been booted.

@@boottime

Returns the date and time Adaptive Server was last booted.

@@bulkarraysize

Returns the number of rows to be buffered in local server memory before being transferred using the bulk copy interface Used only with Component Integration Services for transferring rows to a remote server using select into. For more information, see the Component Integration Services User’s Guide.

@@bulkbatchsize

Returns the number of rows transferred to a remote server via select into proxy_table using the bulk interface. Used only with Component Integration Services for transferring rows to a remote server using select into. For more information, see the Component Integration Services User’s Guide.

@@char_convert

Returns 0 if character set conversion is not in effect. Returns 1 if character set conversion is in effect.

@@cis_rpc_handling

Returns 0 if cis rpc handling is off. Returns 1 if cis rpc handling is on. For more information, see the Component Integration Services User’s Guide.

@@cis_version

Returns the date and version of Component Integration Services.

@@client_csexpansion

Returns the expansion factor used when converting from the server character set to the client character set. For example, if it contains a value of 2, a character in the server character set could take up to twice the number of bytes after translation to the client character set.

@@client_csid

Returns -1 if the client character set has never been initialized. Returns the client character set ID from syscharsets for the connection if the client character set has been initialized.

@@client_csname

Returns NULL if client character set has never been initialized; returns the name of the character set for the connection if the client character set has been initialized.

@@cmpstate

Returns the current mode of Adaptive Server in a high availability environment.

@@connections

Returns the number of user logins attempted.

@@cpu_busy

Returns the number of seconds, in CPU time, that Adaptive Server's CPU was performing Adaptive Server work.

@@cursor_rows

A global variable designed specifically for scrollable cursors. Displays the total number of rows in the cursor result set. Returns the following values: –1:

  • The cursor is dynamic. Because dynamic cursors reflect all changes, the number of rows that qualify for the cursor is constantly changing. You can never be certain that all the qualified rows are retrieved.

  • The cursor is semi_sensitive and scrollable, but the scrolling worktable is not yet fully populated. The number of rows that qualify the cursor is unknown at the time this value is retrieved.

0: Either no cursors are open, no rows qualify for the last opened cursor, or the last open cursor is closed or deallocated.

n: The last opened or fetched cursor result set is fully populated. The value returned is the total number of rows in the cursor result set.

@@curloid

Either no cursors are open, no rows qualify for the last opened cursor, or the last open cursor is closed or deallocated.

@@datefirst

Set using set datefirst n where n is a value between 1 and 7. Returns the current value of @@datefirst, indicating the specified first day of each week, expressed as tinyint.

The default value in Adaptive Server is Sunday (based on the us_language default), which you set by specifying set datefirst 7. See the datefirst option of the set command for more information on settings and values.

@@dbts

Returns the timestamp of the current database.

@@error

Returns the error number most recently generated by the system.

@@errorlog

Returns the full path to the directory in which the Adaptive Server errorlog is kept, relative to $SYBASE directory (%SYBASE% on NT).

@@failedoverconn

Returns a value greater than 0 if the connection to the primary companion has failed over and is executing on the secondary companion server. Used only in a high availability environment, and is session-specific.

@@fetch_status

Returns values: 0: fetch operation successful; –1: fetch operation unsuccessful; –2: value reserved for future use.

@@guestuserid

Returns the ID of the guest user.

@@hacmpservername

Returns the name of the companion server in a high availability setup.

@@haconnection

Returns a value greater than 0 if the connection has the failover property enabled. This is a session-specific property.

@@heapmemsize

Returns the size of the heap memory pool, in bytes. See the System Administration Guide for more information on heap memory.

@@identity

Returns the most recently generated IDENTITY column value.

@@idle

Returns the number of seconds, in CPU time, that Adaptive Server has been idle.

@@invaliduserid

Returns a value of -1 for an invalid user ID.

@@io_busy

Returns the number of seconds in CPU time that Adaptive Server has spent doing input and output operations.

@@isolation

Returns the value of the session-specific isolation level (0, 1, or 3) of the current Transact-SQL program.

@@kernel_addr

Returns the starting address of the first shared memory region that contains the kernel region. The result is in the form of 0xaddress pointer value.

@@kernel_size

Returns the size of the kernel region that is part of the first shared memory region.

@@langid

Returns the server-wide language ID of the language in use, as specified in syslanguages.langid.

@@language

Returns the name of the language in use, as specified in syslanguages.name.

@@lock_timeout

Set using set lock wait n. Returns the current lock_timeout setting, in milliseconds. @@lock_timeout returns the value of n. The default value is no timeout. If no set lock wait n is executed at the beginning of the session, @@lock_timeout returns -1.

@@maxcharlen

Returns the maximum length, in bytes, of a character in Adaptive Server's default character set.

@@max_connections

Returns the maximum number of simultaneous connections that can be made with Adaptive Server in the current computer environment. You can configure Adaptive Server for any number of connections less than or equal to the value of @@max_connections with the number of user connections configuration parameter.

@@maxgroupid

Returns the highest group user ID. The highest value is 1048576.

@@maxpagesize

Returns the server's logical page size.

@@max_precision

Returns the precision level used by decimal and numeric datatypes set by the server. This value is a fixed constant of 38.

@@maxspid

Returns maximum valid value for the spid.

@@maxsuid

Returns the highest server user ID. The default value is 2147483647.

@@maxuserid

Returns the highest user ID. The highest value is 2147483647.

@@mempool_addr

Returns the global memory pool table address. The result is in the form 0xaddress pointer value. This variable is for internal use.

@@min_poolsize

Returns the minimum size of a named cache pool, in kilobytes. It is calculated based on the DEFAULT_POOL_SIZE, which is 256, and the current value of max database page size.

@@mingroupid

Returns the lowest group user ID. The lowest value is 16384.

@@minspid

Returns 1, which is the lowest value for spid.

@@minsuid

Returns the minimum server user ID. The lowest value is -32768.

@@minuserid

Returns the lowest user ID. The lowest value is -32768.

@@monitors_active

Reduces the number of messages displayed by sp_sysmon.

@@ncharsize

Returns the maximum length, in bytes, of a character set in the current server default character set.

@@nestlevel

Returns the current nesting level.

@@nodeid

Returns the current installation's 48-bit node identifier. Adaptive Server generates a nodeid the first time the master device is first used, and uniquely identifies an Adaptive Server installation.

@@optgoal

Returns the current optimization goal setting for query optimization

@@options

Returns a hexadecimal representation of the session's set options.

@@opttimeout

Returns the current optimization timeout limit setting for query optimization

@@pack_received

Retruns the number of input packets read by Adaptive Server.

@@pack_sent

Returns the nmber of output packets written by Adaptive Server.

@@packet_errors

Returns the number of errors detected by Adaptive Server while reading and writing packets.

@@pagesize

Returns the server’s virtual page size.

@@parallel_degree

Returns the current maximum parallel degree setting.

@@probesuid

Returns a value of 2 for the probe user ID.

@@procid

Returns the stored procedure ID of the currently executing procedure.

@@recovery_state

Indicates whether Adaptive Server is in recovery based on these returns:

  • NOT_IN_RECOVERY – Adaptive Server is not in startup recovery or in failover recovery. Recovery has been completed and all databases that can be online are brought online.

  • RECOVERY_TUNING – Adaptive Server is in recovery (either startup or failover) and is tuning the optimal number of recovery tasks.

  • BOOTIME_RECOVERY – Adaptive Server is in startup recovery and has completed tuning the optimal number of tasks. Not all databases have been recovered.

  • FAILOVER_RECOVER – Adaptive Server is in recovery during an HA failover and has completed tuning the optimal number of recovery tasks. All databases are not brought online yet.

@@repartition_degree

Returns the current dynamic repartitioning degree setting

@@resource_granularity

Returns the maximum resource usage hint setting for query optimization

@@rowcount

The value of @@rowcount is affected by whether the specified cursor is forward-only or scrollable.

If the cursor is the default, non-scrollable cursor, the value of @@rowcount increments one by one, in the forward direction only, until the number of rows in the result set are fetched.These rows are fetched from the underlying tables to the client. The maximum value for @@ rowcount is the number of rows in the result set.

In the default cursor, @@rowcount is set to 0 by any command that does not return or affect rows, such as an if or set command, or an update or delete statement that does not affect any rows.

If the cursor is scrollable, there is no maximum value for @@rowcount. The value continues to increment with each fetch, regardless of direction, and there is no maximum value. The @@rowcount value in scrollable cursors reflects the number of rows fetched from the result set, not from the underlying tables, to the client.

@@scan_parallel_degree

Returns the current maximum parallel degree setting for nonclustered index scans.

@@servername

Returns the name of Adaptive Server.

@@setrowcount

Returns the current value for set rowcount

@@shmem_flags

Returns the shared memory region properties. This variable is for internal use. There are a total of 13 different properties values corresponding to 13 bits in the integer. The valid values represented from low to high bit are: MR_SHARED, MR_SPECIAL, MR_PRIVATE, MR_READABLE, MR_WRITABLE, MR_EXECUTABLE, MR_HWCOHERENCY, MR_SWCOHERENC, MR_EXACT, MR_BEST, MR_NAIL, MR_PSUEDO, MR_ZERO.

@@spid

Returns the server process ID of the current process.

@@sqlstatus

Returns status information (warning exceptions) resulting from the execution of a fetch statement.

@@ssl_ciphersuite

Returns NULL if SSL is not used on the current connection; otherwise, it returns the name of the cipher suite you chose during the SSL handshake on the current connection.

@@stringsize

Returns the amount of character data returned from a toString() method. The default is 50. Max values may be up to 2GB. A value of zero specifies the default value. See the Component Integration Services User’s Guide for more information.

@@tempdbid

Returns a valid temporary database ID (dbid) of the session’s assigned temporary database.

@@textcolid

Returns the column ID of the column referenced by @@textptr.

@@textdataptnid

Returns the partition ID of a text partition containing the column referenced by @@textptr.

@@textdbid

Returns the database ID of a database containing an object with the column referenced by @@textptr.

@@textobjid

Returns the object ID of an object containing the column referenced by @@textptr.

@@textptnid

Returns the partition ID of a data partition containing the column referenced by @@textptr.

@@textptr

Returns the text pointer of the last text, unitext, or image column inserted or updated by a process (Not the same as the textptr function).

@@textptr_parameters

Returns 0 if the current status of the textptr_parameters configuration parameter is off. Returns 1 if the current status of the textptr_parameters if on. See the Component Integration Services User’s Guide for more information.

@@textsize

Returns the limit on the number of bytes of text, unitext, or image data a select returns. Default limit is 32K bytes for isql; the default depends on the client software. Can be changed for a session with set textsize.

@@textts

Returns the text timestamp of the column referenced by @@textptr.

@@thresh_hysteresis

Returns the decrease in free space required to activate a threshold. This amount, also known as the hysteresis value, is measured in 2K database pages. It determines how closely thresholds can be placed on a database segment.

@@timeticks

Returns the number of microseconds per tick. The amount of time per tick is machine-dependent.

@@total_errors

Returns the number of errors detected by Adaptive Server while reading and writing.

@@total_read

Returns the number of disk reads by Adaptive Server.

@@total_write

Returns the number of disk writes by Adaptive Server.

@@tranchained

Returns 0 if the current transaction mode of the Transact-SQL program is unchained. Returns 1 if the current transaction mode of the Transact-SQL program is chained.

@@trancount

Returns the nesting level of transactions in the current user session.

@@transactional_rpc

Returns 0 if RPCs to remote servers are transactional. Returns 1 if RPCs to remote servers are not transactional. For more information, see enable xact coordination and set option transactional_rpc in the Reference Manual. Also, see the Component Integration Services User’s Guide.

@@transtate

Returns the current state of a transaction after a statement executes in the current user session.

@@unicharsize

Returns 2, the size of a character in unichar.

@@version

Returns the date, version string, and so on of the current release of Adaptive Server.

@@version_number

Returns the whole version of the current release of Adaptive Server as an integer

@@version_as_integer

Returns the number of the last upgrade version of the current release of Adaptive Server as an integer. For example, @@version_as_integer returns 12500 if you are running Adaptive Server version 12.5, 12.5.0.3, or 12.5.1.





Copyright © 2005. Sybase Inc. All rights reserved. Chapter 4: Expressions, Identifiers, and Wildcard Characters

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