75 lines
2.7 KiB
Python
75 lines
2.7 KiB
Python
#------------------------------------------------------------------------------
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# Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
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#
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# Portions Copyright 2007-2015, Anthony Tuininga. All rights reserved.
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#
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# Portions Copyright 2001-2007, Computronix (Canada) Ltd., Edmonton, Alberta,
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# Canada. All rights reserved.
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#------------------------------------------------------------------------------
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#------------------------------------------------------------------------------
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# ReturnLobsAsStrings.py
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# Returns all CLOB values as strings and BLOB values as bytes. The
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# performance of this technique is significantly better than fetching the LOBs
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# and then reading the contents of the LOBs as it avoids round-trips to the
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# database. Be aware, however, that this method requires contiguous memory so
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# is not usable for very large LOBs.
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#
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# This script requires cx_Oracle 5.0 and higher.
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#------------------------------------------------------------------------------
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from __future__ import print_function
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import cx_Oracle
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import SampleEnv
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def OutputTypeHandler(cursor, name, defaultType, size, precision, scale):
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if defaultType == cx_Oracle.CLOB:
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return cursor.var(cx_Oracle.LONG_STRING, arraysize = cursor.arraysize)
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if defaultType == cx_Oracle.BLOB:
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return cursor.var(cx_Oracle.LONG_BINARY, arraysize = cursor.arraysize)
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connection = cx_Oracle.connect(SampleEnv.GetMainConnectString())
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connection.outputtypehandler = OutputTypeHandler
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cursor = connection.cursor()
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# add some data to the tables
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print("Populating tables with data...")
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cursor.execute("truncate table TestClobs")
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cursor.execute("truncate table TestBlobs")
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longString = ""
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for i in range(10):
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char = chr(ord('A') + i)
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longString += char * 25000
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# uncomment the line below for cx_Oracle 5.3 and earlier
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# cursor.setinputsizes(None, cx_Oracle.LONG_STRING)
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cursor.execute("insert into TestClobs values (:1, :2)",
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(i + 1, "STRING " + longString))
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# uncomment the line below for cx_Oracle 5.3 and earlier
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# cursor.setinputsizes(None, cx_Oracle.LONG_BINARY)
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cursor.execute("insert into TestBlobs values (:1, :2)",
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(i + 1, longString.encode("ascii")))
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connection.commit()
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# fetch the data and show the results
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print("CLOBS returned as strings")
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cursor.execute("""
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select
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IntCol,
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ClobCol
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from TestClobs
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order by IntCol""")
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for intCol, value in cursor:
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print("Row:", intCol, "string of length", len(value))
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print()
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print("BLOBS returned as bytes")
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cursor.execute("""
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select
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IntCol,
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BlobCol
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from TestBlobs
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order by IntCol""")
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for intCol, value in cursor:
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print("Row:", intCol, "string of length", value and len(value) or 0)
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