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#------------------------------------------------------------------------------
# Copyright (c) 2020, 2022, Oracle and/or its affiliates.
#
# This software is dual-licensed to you under the Universal Permissive License
# (UPL) 1.0 as shown at https://oss.oracle.com/licenses/upl and Apache License
# 2.0 as shown at http://www.apache.org/licenses/LICENSE-2.0. You may choose
# either license.
#
# If you elect to accept the software under the Apache License, Version 2.0,
# the following applies:
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#------------------------------------------------------------------------------
#------------------------------------------------------------------------------
# cqn_pool.py
#
# Demonstrates using continuous query notification in Python, a feature that is
# available in Oracle Database 11g and later. Once this script is running, use
# another session to insert, update or delete rows from the table TestTempTable
# and you will see the notification of that change.
#
# This script differs from cqn.py in that it shows how a connection can be
# acquired from a session pool and used to query the changes that have been
# made.
#------------------------------------------------------------------------------
import time
import oracledb
import sample_env
# this script is currently only supported in python-oracledb thick mode
oracledb.init_oracle_client(lib_dir=sample_env.get_oracle_client())
registered = True
def callback(message):
global registered
if not message.registered:
print("Deregistration has taken place...")
registered = False
return
connection = pool.acquire()
for query in message.queries:
for table in query.tables:
if table.rows is None:
print("Too many row changes detected in table", table.name)
continue
num_rows_deleted = 0
print(len(table.rows), "row changes detected in table", table.name)
for row in table.rows:
if row.operation & oracledb.OPCODE_DELETE:
num_rows_deleted += 1
continue
ops = []
if row.operation & oracledb.OPCODE_INSERT:
ops.append("inserted")
if row.operation & oracledb.OPCODE_UPDATE:
ops.append("updated")
cursor = connection.cursor()
cursor.execute("""
select IntCol
from TestTempTable
where rowid = :rid""",
rid=row.rowid)
int_col, = cursor.fetchone()
print(" Row with IntCol", int_col, "was", " and ".join(ops))
if num_rows_deleted > 0:
print(" ", num_rows_deleted, "rows deleted")
print("=" * 60)
pool = oracledb.create_pool(user=sample_env.get_main_user(),
password=sample_env.get_main_password(),
dsn=sample_env.get_connect_string(),
min=1, max=4, increment=1, events=True)
with pool.acquire() as connection:
qos = oracledb.SUBSCR_QOS_QUERY | oracledb.SUBSCR_QOS_ROWIDS
sub = connection.subscribe(callback=callback, timeout=1800,
qos=qos, client_initiated=True)
print("Subscription created with ID:", sub.id)
query_id = sub.registerquery("select * from TestTempTable")
print("Registered query with ID:", query_id)
while registered:
print("Waiting for notifications....")
time.sleep(5)
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