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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.
ISQL or Application Programs
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][,...]
- DBEnvironmentName
identifies the DBEnvironment in which the session is established.
Unless you specify an absolute path name, the name you specify is assumed
to be relative to your current working directory.
- 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.
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.
You can issue the START DBE statement only if you have DBA authority.
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 '../sampledb/PartsDBE'
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