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The START DBE statement establishes a connection with a given DBEnvironment and
establishes a set of startup parameters that apply to this and all subsequent
connections until all connections to the DBEnvironment have been terminated.
Any startup parameters not explicitly specified are taken from the DBECon
file.
The changes are only temporary for START DBE parameters; use START DBE NEW to specify the start up parameters to be stored in the DBECon file in a new DBE. Use SQLUtil to change the parameters in the DBECon file in an existing DBE.
Scope | |
ISQL or Application Programs
SQL Syntax | |
START DBE 'DBEnvironmentName' [AS ConnectionName'] [MULTI] [ BUFFER = (DataBufferPages, LogBufferPages) TRANSACTION = MaxTransactions MAXIMUM TIMEOUT = { TimeoutValue [ SECONDS MINUTES ] NONE } DEFAULT TIMEOUT = { TimeoutValue [ SECONDS MINUTES ] MAXIMUM } RUN BLOCK = ControlBlockPages ] |,...| Parameters | |
- DBEnvironmentName
identifies the DBEnvironment in which the
session is established.
Name qualification follows standard MPE/iX file naming conventions.
Unless you specify
a group and account
name, the name you specify is
assumed to be relative to your current
group and account.
DBEnvironmentName cannot exceed 36 bytes.
You can also use an MPE/iX back reference
for DBEnvironmentName as shown in the following example:
:FILE DBE = PartsDBE.SomeGrp.Acct
START DBE '*DBE'
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- ConnectionName
associates a user specified name with
this connection.
ConnectionName must be unique for each DBEnvironment connection
within an application or an ISQL session.
If a ConnectionName is not specified, DBEnvironmentName is the default.
ConnectionName cannot exceed 128 bytes.
- MULTI
indicates the DBEnvironment can be accessed by multiple
users simultaneously. If omitted, the DBEnvironment can be accessed
only by the user issuing the START DBE statement. If the MULTI option
is specified, other users can start DBE sessions by using the
CONNECT statement.
- DataBufferPages
specifies the number of 4096-byte data buffer
pages to be used. Data buffer pages hold index and data pages.
You can request up to 50,000 data buffer pages.
The minimum number of data buffers is 15. The default number is 100.
The total number of data buffer pages and runtime control block pages
cannot exceed 256 Mbytes.
See the "ALLBASE/SQL Limits" Appendix in the ALLBASE/SQL Database Administration Guide.
- LogBufferPages
specifies the number of 512-byte log buffer pages
to be used.
You can request from 24 to 1024 log buffer pages, limited by the amount
of storage available. The default number of log buffer pages is 24.
- MaxTransactions
specifies the maximum number of concurrent
transactions that can be concurrently active. You can specify a value
in the range from 2 to 240. The default is 50.This value overrides
the maximum value stored in the DBECon file. Any attempt to start a
transaction beyond the maximum limit waits for the specified TIMEOUT
and returns an error if TIMEOUT is exceeded.
For each user logged on to the system at any point in time you should
allow 2 concurrent transactions for just being connected to the DBE.
- MAXIMUM TIMEOUT
specifies the maximum user timeout value.
This value temporarily overrides the maximum stored in the DBECon
file. When no value is specified, the DBECon file value is the default.
- DEFAULT TIMEOUT
specifies the maximum user timeout value.
This value temporarily overrides the maximum stored in the DBECon
file. When no value is specified, the DBECon file value is the default.
- TimeoutValue
is an integer literal greater than zero. If
the TimeoutValue is not qualified by MINUTES, SECONDS is assumed. If
representing seconds, TimeoutValue must be in the range of
1 to 2,147,483,647. If representing minutes, TimeoutValue must
be in the range of 1 to 35,791,394.
- ControlBlockPages
specifies the number of runtime control
blocks allocated.
You can specify a value from 17 to 2,000 pages for this parameter. The
default is 37 pages. The total number of data buffer pages and runtime
control block pages cannot exceed 256 Mbytes.
Description | |
Any parameters (except the MULTI option) not specified in the
START DBE statement are assigned values currently stored
in the DBECon file (which has the same name as the DBEnvironment name
specified). The user mode in the DBECon file is always
overridden by the user mode specified in the START DBE
statement.
Normally, if autostart mode has the value of ON, DBE sessions are established
by using the CONNECT statement. The START DBE statement is needed only
to temporarily override DBECon file parameters for the DBEnvironment,
as when you need to start a single-user DBEnvironment in multiuser
mode or vice versa.
When you issue the CONNECT statement and autostart mode is on,
ALLBASE/SQL executes a START DBE statement on your behalf if no
sessions for the DBEnvironment are active. ALLBASE/SQL starts your
session using all parameters in the current DBECon file.
If autostart mode has a value of OFF, you always use the START DBE statement
to start up a DBEnvironment. If the MULTI option is not specified, the DBEnvironment
is started up in single-user mode. If the MULTI option is specified, the
DBEnvironment is started up in multiuser mode and other users can
initiate DBE sessions by using the CONNECT statement.
Timeout values set in the START DBE statement remain
in effect only as long as there is a session established for
connected DBEnvironments and do not modify the values stored in the
DBECon file.
If no MAXIMUM TIMEOUT limit is specified, the MAXIMUM TIMEOUT limit
stored in the DBECon file remains in effect. If no DEFAULT TIMEOUT
value is specified, the DEFAULT TIMEOUT value stored in the DBECon file
remains in effect.
If MAXIMUM TIMEOUT = NONE, infinity (no timeout) is assumed. If
DEFAULT TIMEOUT = MAXIMUM, the value of MAXIMUM TIMEOUT is assumed.
The DEFAULT TIMEOUT value may not exceed the MAXIMUM TIMEOUT value.
No connections to the DBEnvironment can be in
effect when this command is issued.
The START DBE statement is also used before using the
START DBE NEWLOG statement.
Refer to the START DBE NEWLOG statement for additional
information.
Authorization | |
You can issue the START DBE statement only if you have
DBA authority. Example | |
The sample DBEnvironment is started in single-user mode.
All parameters except the user mode in the DBECon file are
used for the duration of the single-user session. After
this session ends, a CONNECT statement can be used to establish
a multiuser session for this DBEnvironment, because the user mode in
the DBECon file is still multiuser and the autostart flag is still
ON.
START DBE 'PartsDBE.SomeGrp.SomeAcct'
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