DatabaseHandle :: OpenMultiple - Open multiple database source
The function returns true in case of error(s). Otherwise after opening, the database handle refers to a multiple database source (overload object space). When the passed path contains a single database reference, an ordinary database handle has been opened.
Implementation details
The function opens all database references passed in the database path ( cpath ). Before extracting database references, option variables (%...%) are resolved. Database references are separated by semicolon. No semicolon is required after last file name. Each database reference must refer to a valid file location. The database reference on top of the path list has highest priority.
Only the top database is opened with the access mode passed in accopt . All following databases are opened with read mode, i.e. changed can be stored in top database, only.
When running a database in client/server mode ( local_resource is RES_server ), option variables are not resolved but passed to the server.
- dicthdl_refc - - internal feature (not documented)
- cpath - Complete file or directory path
- accopt - Access mode
- w_netopt
- Multi-user option
Passing this value as true ( YES ) indicates that multi-user access is requested. False ( NO ) indicates exclusive use of database. Accessing a database in update or write mode, NO guarantees absolute exclusive access.
- key_buffer
- - internal feature (not documented)
Default: NString::Null()
- online_version
- Online versioning option
When this option is set the database will be enabled for on line versioning. When the option is set to NO the system variable ONLINE_VERSION is checked instead.
Default: NO
- local_ressources
- Resource type
Depending on the resource type the database or dictionary is opened on the client or server side.
Default: RES_automatic
- sysenv
- System application
This option indicates that the application is running as system application. In this case context functions are disabled and will not be executed. This option should never be set in normal applications because this may lead to logical inconsistency of the database.
When running a replication client, this option contains the value 2. Running a replication client in a system application, the option contains the value 3.
For maintenance purposes, 4 might be passed in the variable. In this case, versions will not be upgraded automatically.
Default: NO
- schema_version_w
- Scheme version
Schema versions are numbered consecutively beginning with 0. In order to refer to the current schema version, the version value may be set to -1.
Default: CUR_VERSION
- rb_type
- - internal feature (not documented)
Default: RBT_ODABA
- upgrade_opt
- Automatic system upgrade
When system version has been changed, i.e. structure for internal headers has been changed, usually an automatic upgrade to current system version will be done, when opening a database in write mode. In order to suppress system version upgrade, this property may be set to false . The default setting is true .
After upgrading a database to a newer system version, the database cannot be accessed with older software versions.
In order to disable automatic system upgrade for all databases opened in an application, the option may be set on global level to false (or NO ):
SYSTEM_UPGRADE=NO
Default: YES
- opt_64bit
- 64 bit compiler version
Values have following meaning:
- 0 - automatically determine large file option
- 1 - large file requested
- 2 - large file not supported (file size limited to 2GB)