74 lines
2.9 KiB
Python
74 lines
2.9 KiB
Python
#------------------------------------------------------------------------------
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# Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
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#------------------------------------------------------------------------------
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#------------------------------------------------------------------------------
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# CQN2.py
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# This script demonstrates using continuous query notification in Python, a
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# feature that is available in Oracle 11g and later. Once this script is
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# running, use another session to insert, update or delete rows from the table
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# cx_Oracle.TestTempTable and you will see the notification of that change.
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#
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# This script differs from CQN.py in that it shows how a connection can be
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# acquired from a session pool and used to query the changes that have been
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# made.
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#
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# This script requires cx_Oracle 7 or higher.
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#------------------------------------------------------------------------------
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import cx_Oracle
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import SampleEnv
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import time
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registered = True
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def callback(message):
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global registered
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if not message.registered:
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print("Deregistration has taken place...")
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registered = False
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return
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connection = pool.acquire()
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for query in message.queries:
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for table in query.tables:
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if table.rows is None:
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print("Too many row changes detected in table", table.name)
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continue
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numRowsDeleted = 0
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print(len(table.rows), "row changes detected in table", table.name)
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for row in table.rows:
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if row.operation & cx_Oracle.OPCODE_DELETE:
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numRowsDeleted += 1
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continue
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ops = []
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if row.operation & cx_Oracle.OPCODE_INSERT:
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ops.append("inserted")
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if row.operation & cx_Oracle.OPCODE_UPDATE:
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ops.append("updated")
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cursor = connection.cursor()
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cursor.execute("""
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select IntCol
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from TestTempTable
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where rowid = :rid""",
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rid=row.rowid)
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intCol, = cursor.fetchone()
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print(" Row with IntCol", intCol, "was", " and ".join(ops))
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if numRowsDeleted > 0:
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print(" ", numRowsDeleted, "rows deleted")
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print("=" * 60)
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pool = cx_Oracle.SessionPool(SampleEnv.GetMainUser(),
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SampleEnv.GetMainPassword(), SampleEnv.GetConnectString(), min=2,
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max=5, increment=1, events=True, threaded=True)
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connection = pool.acquire()
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sub = connection.subscribe(callback=callback, timeout=1800,
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qos=cx_Oracle.SUBSCR_QOS_QUERY | cx_Oracle.SUBSCR_QOS_ROWIDS)
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print("Subscription created with ID:", sub.id)
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queryId = sub.registerquery("select * from TestTempTable")
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print("Registered query with ID:", queryId)
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connection.close()
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while registered:
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print("Waiting for notifications....")
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time.sleep(5)
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