iframe-proxy | Sunbelt Computer Software

History

71 lines (65 loc) · 2.71 KB

Raw

#------------------------------------------------------------------------------

# 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 usable for very large LOBs.

# This script requires cx_Oracle 5.0 and higher.

#------------------------------------------------------------------------------

import cx_Oracle as oracledb

import sample_env

def output_type_handler(cursor, name, default_type, size, precision, scale):

if default_type == oracledb.CLOB:

return cursor.var(oracledb.LONG_STRING, arraysize=cursor.arraysize)

if default_type == oracledb.BLOB:

return cursor.var(oracledb.LONG_BINARY, arraysize=cursor.arraysize)

connection = oracledb.connect(sample_env.get_main_connect_string())

connection.outputtypehandler = output_type_handler

cursor = connection.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

# uncomment the line below for cx_Oracle 5.3 and earlier

# cursor.setinputsizes(None, oracledb.LONG_STRING)

cursor.execute("insert into TestClobs values (:1, :2)",

(i + 1, "STRING " + long_string))

# uncomment the line below for cx_Oracle 5.3 and earlier

# cursor.setinputsizes(None, oracledb.LONG_BINARY)

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)

Sunbelt Computer Software

PL/B Language Development and Support

Navigation Menu

Sunbelt Computer Software

PL/B Language Development and Support

FilesExpand file tree

return_lobs_as_strings.py

Latest commit

History

return_lobs_as_strings.py

File metadata and controls