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#------------------------------------------------------------------------------
# Copyright (c) 2016, 2022, Oracle and/or its affiliates.
#
# Portions Copyright 2007-2015, Anthony Tuininga. All rights reserved.
#
# Portions Copyright 2001-2007, Computronix (Canada) Ltd., Edmonton, Alberta,
# Canada. All rights reserved.
#
# 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.
#------------------------------------------------------------------------------
#------------------------------------------------------------------------------
# return_lobs_as_strings.py
#
# Returns all CLOB values as strings and BLOB values as bytes. The
# performance of this technique is significantly better than fetching the LOBs
# and then reading the contents of the LOBs as it avoids round-trips to the
# database. Be aware, however, that this method requires contiguous memory so
# is not suitable for very large LOBs.
#------------------------------------------------------------------------------
import oracledb
import sample_env
# determine whether to use python-oracledb thin mode or thick mode
if not sample_env.get_is_thin():
oracledb.init_oracle_client(lib_dir=sample_env.get_oracle_client())
# indicate that LOBS should not be fetched
oracledb.defaults.fetch_lobs = False
connection = oracledb.connect(user=sample_env.get_main_user(),
password=sample_env.get_main_password(),
dsn=sample_env.get_connect_string())
with connection.cursor() as cursor:
# add some data to the tables
print("Populating tables with data...")
cursor.execute("truncate table TestClobs")
cursor.execute("truncate table TestBlobs")
long_string = ""
for i in range(10):
char = chr(ord('A') + i)
long_string += char * 25000
cursor.execute("insert into TestClobs values (:1, :2)",
(i + 1, "STRING " + long_string))
cursor.execute("insert into TestBlobs values (:1, :2)",
(i + 1, long_string.encode("ascii")))
connection.commit()
# fetch the data and show the results
print("CLOBS returned as strings")
cursor.execute("""
select
IntCol,
ClobCol
from TestClobs
order by IntCol""")
for int_col, value in cursor:
print("Row:", int_col, "string of length", len(value))
print()
print("BLOBS returned as bytes")
cursor.execute("""
select
IntCol,
BlobCol
from TestBlobs
order by IntCol""")
for int_col, value in cursor:
print("Row:", int_col, "string of length", value and len(value) or 0)
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