Create a connection to one or more databases through an eXtremeSQL engine.
Connection exdb.connect(dbname, port, nodes, nReplicas, maxConnectAttempts,
useConnectionPool=useConnectionPool,
txBufSize=txBufSize, localDomain=local,
connectTimeout=2000L, readTimeout=1200*1000L,
sql_login=sql_login, sql_password=sql_password,
ssl_params=ssl_params,
async=async, nworkers=nWorkers)
| dbname | The database name or host IP: when port is specified, connect to a remote database; otherwise connect to the local database (conventional or shared memory) by dbname |
| port | The port to connect on; when specified connect to a remote database using the host (extracted from dbname) and specified port |
| nodes | The nodes list; when specified connect to distributed databases using the host and port values specified in nodes |
| nReplicas | The number of HA replicas; this number should be a divider of the number of nodes meaning that the remainder of nNodes / nReplicas is 0. For example, the values of nNodes and nReplicas could be (4 and 2) or (12 and
3) but not (6 and 4) because 6 % 4 = 2 |
| maxConnectAttempts | The maximum number of attempts to connect to distributed nodes or HA replicas |
| useConnectionPool | If true, then create a connection pool to enable parallel query execution for sequences |
| txBufSize | Specifies the size of transmit buffer used to serialize requests to be sent to the server (default is 64k) |
| localDomain | Indicates that Unix Domain Socket instead of networked TCP socket is used for RSQL communication which is possible only when server and client are on the same host |
| connectTimeout | The timeout for each connect attempt in milliseconds; so the total connection time can be up to connectTimeout * maxConnectionAttempts milliseconds |
| readTimeout | The timeout for read operations in milliseconds |
| sql_login | Login username when authentication is required |
| sql_password |
Login password when authentication is required |
| ssl_params | A pointer to a mco_ssl_params_t structure containing SSL connection settings |
| async | When True create an AsyncDistributedConnection using nworkers processes to perform multiple queries on the distributed database shards specified in nodes |
| nworkers | When async=True, create nworkers processes to perform multiple queries on the distributed database shards specified in nodes |
This method creates a connection to an eXtremeSQL engine. The connection will be of one of four SQL engine types:
dbname is specified and port is null, a single Connection to a local database is returned (the database can be in conventional or shared memory depending on the runtime loaded), port is specified the host name is extracted from argument dbname, and a RemoteConnection to a single database is returned,nodes is specified a DistributedConnection is returned using the nodes and maxConnectAttempts arguments to create an eXtremeDB High Availability operating on master and replica databases or an eXtremeDB Cluster network of nodes operating on multiple databases or database shards,async=True is specified, then an AsyncDistributedConnection is returned with nworkers processes created for parallel asynchronous execution of multiple queries.| Connection |
The connection to the SQL engine of the type determined by the arguments as explained above |
The following code snippet demonstrates creating connections of different types:
''' Connect to a local in-memory database in conventional memory (with Connection)
'''
is_shm = False
is_debug = True
is_disk = False
tmgr='mursiw'
exdb.init_runtime(is_disk, tmgr, is_shm, is_debug)
conn = exdb.connect(dbname='imdb')
''' Connect to a local in-memory database in shared memory (with Connection)
'''
is_shm = True
is_debug = True
is_disk = False
tmgr='mursiw'
exdb.init_runtime(is_disk, tmgr, is_shm, is_debug)
conn = exdb.connect(dbname='shmdb')
''' Connect to a remote database (with RemoteConnection)
'''
is_shm = False
is_debug = True
is_disk = False
tmgr='mursiw'
exdb.init_runtime(is_disk, tmgr, is_shm, is_debug)
conn = exdb.connect('localhost', 5001)
''' Connect to two remote databases (with DistributedConnection)
'''
is_shm = False
is_debug = True
is_disk = False
tmgr='mursiw'
nodes = ("localhost:5001", "localhost:5002")
exdb.init_runtime(is_disk, tmgr, is_shm, is_debug)
conn = exdb.connect(nodes)
''' Connect to three remote databases (with AsyncDistributedConnection)
'''
is_shm = False
is_debug = True
is_disk = False
tmgr='mursiw'
nodes = ('bogota01:5000', 'bogota02:5001', 'bogota03:5000')
exdb.init_runtime(is_disk, tmgr, is_shm, is_debug)
conn = exdb.connect(nodes, async=True, nWorkers=5) )