Runtime Control in Python

The startup procedure that initializes the eXtremeDB runtime environment in Python applications is implemented in the exdb.init_runtime() method which must be called before any database operations can be performed. The exdb.init_runtime() method accepts the following arguments to set runtime options to and to load specific eXtremeDB libraries:

is_disk	A boolean (True or False) value; if True load disk (persistent storage) versions of libraries; default value is False which means initialize the in-memory runtime
tmgr	A string specifying which transaction manager to use: valid values are 'mursiw' or 'mvcc'; default is 'mursiw' (MURSIW transaction manager)
is_shm	A boolean (True or False) value; if True the shared-memory runtime is to be used; default is False; i.e. use conventional (“in-process” or “local”) memory
is_debug	A boolean (True or False) value; if True the debug version of the runtime is to be used.; default is False; i.e. use the release (optimized “no-debug”) runtime
cluster	A boolean (True or False) value; if True the cluster runtime is to be loaded; default is False; i.e.do not load the cluster runtime. (Note that this flag is mutually exclusive with ha)
ha	A boolean (True or False) value; if True the High Availability (HA) runtime is to be loaded; default is False; i.e. do not load the HA runtime. (Note that this flag is mutually exclusive with cluster)
options	Specifies runtime options; the options can be specified either by an “options=(option,value)” tuple or as a list of “options=(option,value)” tuples (Please refer to the Reference Guide page mco_runtime_setoption() for the list of actual runtime options)
DiskCompression	A boolean (True or False) value; if True the low level file access library with disk compression enabled is to be used; default is False; i.e. do not to use low level disk compression library (Note that this flag is mutually exclusive with UseAsyncIO)
UsePosixLibraries	A boolean (True or False) value; if True the low level posix synchronization primitives library is to be used; default is False; i.e. use the SystemV synchronization primitives library
UseAsyncIO	A boolean (True or False) value; if True the asynchronous disk IO library; default is False; i.e. use the standard synchronous IO library (eg. libmcofu98 on Linux, mcofw32.lib on Windows. Note that Windows only supports synchronous IO so True is not a valid choice for this option on Windows).
iot	A boolean (True or False) value; if True the IoT communication is enabled (see the Active Data Replication page)

The typical sequence of API calls would look like the following:

 
    ...
    is_disk = False
    tmgr = 'mvcc'
    is_shm = True
    is_debug = True
     
    #Load Runtime configuration specified by parameters
    exdb.init_runtime(is_disk, tmgr, is_shm, is_debug)
    ...
 

Persistent Databases

For persistent databases, the exdb.init_runtime() method is called exactly as for an in-memory database except that the argument is_disk=True and possibly the two other arguments: DiskCompression and UseAsyncIO (see table above ). The typical sequence of API calls for a persistent database application would look like the following:

 
    ...
    is_disk = True
    tmgr = 'mvcc'
    is_shm = False
    is_debug = True
     
    #Load Runtime configuration specified by parameters
    exdb.init_runtime(is_disk, tmgr, is_shm, is_debug)
    ...
 

(Please refer to SDK sample python/open for an example.)