99 lines
4.0 KiB
Python
99 lines
4.0 KiB
Python
#------------------------------------------------------------------------------
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# Copyright (c) 2020, 2022, Oracle and/or its affiliates.
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#
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# This software is dual-licensed to you under the Universal Permissive License
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# (UPL) 1.0 as shown at https://oss.oracle.com/licenses/upl and Apache License
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# 2.0 as shown at http://www.apache.org/licenses/LICENSE-2.0. You may choose
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# either license.
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#
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# If you elect to accept the software under the Apache License, Version 2.0,
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# the following applies:
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#------------------------------------------------------------------------------
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#------------------------------------------------------------------------------
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# cqn_pool.py
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#
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# Demonstrates using continuous query notification in Python, a feature that is
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# available in Oracle Database 11g and later. Once this script is running, use
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# another session to insert, update or delete rows from the table TestTempTable
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# 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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import time
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import oracledb
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import sample_env
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# this script is currently only supported in python-oracledb thick mode
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oracledb.init_oracle_client(lib_dir=sample_env.get_oracle_client())
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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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num_rows_deleted = 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 & oracledb.OPCODE_DELETE:
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num_rows_deleted += 1
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continue
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ops = []
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if row.operation & oracledb.OPCODE_INSERT:
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ops.append("inserted")
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if row.operation & oracledb.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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int_col, = cursor.fetchone()
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print(" Row with IntCol", int_col, "was", " and ".join(ops))
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if num_rows_deleted > 0:
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print(" ", num_rows_deleted, "rows deleted")
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print("=" * 60)
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pool = oracledb.create_pool(user=sample_env.get_main_user(),
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password=sample_env.get_main_password(),
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dsn=sample_env.get_connect_string(),
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min=1, max=4, increment=1, events=True)
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with pool.acquire() as connection:
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qos = oracledb.SUBSCR_QOS_QUERY | oracledb.SUBSCR_QOS_ROWIDS
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sub = connection.subscribe(callback=callback, timeout=1800,
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qos=qos, client_initiated=True)
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print("Subscription created with ID:", sub.id)
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query_id = sub.registerquery("select * from TestTempTable")
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print("Registered query with ID:", query_id)
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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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