Open and close an ODB

Since the original ODB system is written in C, handling its data requires initializing several internal structures such as paths, handlers and pointers. These operations must be performed in the backend before accessing the data.

To simplify this process, the odb4py.core module provides two functions to open and close an ODB database.

Open an ODB database

To open an ODB database, the odb_open function from odb4py.core module has to be used. This function is a wrapper around the ODBc_open C function in the original ODB code.

It opens the database and returns an odb.ODBConnection Python object that represents the active ODB session. The function initializes the main ODB parameters, including: the database path, the location of the metadata files, the maximum number of ODB handlers etc.

#-*- coding: utf-8 -*-

# Import function
from odb4py.core import odb_open

# Path to a CCMA database
dbtype = "CCMA"
dbpath = "/".join(("/path/to/odb", dbtype))

# Open the database
conn  = odb_open  (database =dbpath )
print( conn )

<odb.ODBConnection object at 0x7f7ca23eed30>

Close an ODB database

Once the database is no longer needed, it should be closed using the odb_close method. This function releases allocated handlers, poolmask arrays (if used), and reinitializes the internal ODB structures.

The function takes no arguments. It automatically looks for all variables that were initialized during the connection phase.

Note

Most ODB operations are available as methods of the ODBConnection object returned by odb_open. This means that once a database is opened, all ODB-related functions in core module can be accessed directly through the connection object.

#-*- coding: utf-8 -*-
import sys

# Import function
from odb4py.core import odb_open

# Path to a CCMA database
dbtype = "CCMA"
dbpath = "/".join(("/path/to/odb", dbtype))

# Open the database
conn  = odb_open (database =dbpath )

# Call the other methods and manipulate the data
...
...

# Close the database
conn.odb_close()