Oracle PL/SQL Programming
The PL/SQL Channel
Input/Output and Oracle PL/SQL
Manipulating BFILEs with
DBMS_LOB
Steven Feuerstein
steven@stevenfeuerstein.com
www.StevenFeuerstein.com
www.PLSQLChallenge.com
Oracle PL/SQL Programming
Quick Reminders
• Download code and PowerPoint documents
from www.ToadWorld.com/SF (aka, "PL/SQL
Obsession").
• Make sure you are comfortable with the
material covered in the previous lessons in
this series.
– How to use UTL_FILE to read and write operating
system files.
Copyright 2010 Feuerstein and Associates
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Oracle PL/SQL Programming
DBMS_LOB and BFILEs
• Oracle allows you to also manipulate binary files
or BFILEs through the DBMS_LOB package.
– The intention is to work with really big files, but they
don't have to be.
• A BFILE is a pointer to an OS file.
• This will not constitute a training on working with
LOBs!
– It is a big and complex topic; I will simply introduce
you to some of the features related to manipulating
BFILEs from within a PL/SQL block.
Copyright 2010 Feuerstein and Associates
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Oracle PL/SQL Programming
DBMS_LOB BFILE functionality
• Open and close BFILEs
• Compare two BFILES with COMPARE.
• Get information about a BFILE
– Name and location? exists? length?
• Read contents of BFILE
– They are read-only structures!
• And more...
– Read BFILE into LOB
– Perform INSTR and SUBSTR operations on a BFILE.
Copyright 2010 Feuerstein and Associates
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Oracle PL/SQL Programming
Open and Close BFILES
DECLARE
l_bfile
BFILE := BFILENAME ('DEMO', 'exec_ddl_from_file2.sql');
BEGIN
DBMS_OUTPUT.put_line ('Exists? ' || DBMS_LOB.fileexists (l_bfile));
DBMS_OUTPUT.put_line ('Open before open? ' || DBMS_LOB.fileisopen (l_bfile));
DBMS_LOB.fileopen (l_bfile);
DBMS_OUTPUT.put_line ('Open after open? ' || DBMS_LOB.fileisopen (l_bfile));
DBMS_LOB.fileclose (l_bfile);
DBMS_OUTPUT.
put_line ('Open after close? ' || DBMS_LOB.fileisopen (l_bfile));
END;
• Initialize BFILE pointer with the BFILENAME
function.
• Then you can open the bfile, perform operations
on it (details to come), and close that file when
you are done.
Copyright 2010 Feuerstein and Associates
bfile_open_close.sql
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Oracle PL/SQL Programming
Compare two BFILES with COMPARE
DECLARE
l_bfile1
BFILE := BFILENAME ('TEMP', 'file1.txt');
l_bfile2
BFILE := BFILENAME ('TEMP', 'file2.txt');
BEGIN
DBMS_LOB.fileopen (l_bfile1); DBMS_LOB.fileopen (l_bfile2);
DBMS_OUTPUT.put_line (
'Equal? ' ||
DBMS_LOB.compare (
file_1 => l_bfile1,
file_2 => l_bfile2
, amount => 33, offset_1 => 1, offset_2 => 1));
DBMS_LOB.fileclose (l_bfile1); DBMS_LOB.fileclose (l_bfile2);
END;
• Use the COMPARE program to find out if two
BFILEs are the same: 0 = same, 1 = different.
– Specify amount of file you want to compare, and
the offset locations in each.
Copyright 2010 Feuerstein and Associates
bfile_compare.sql
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Oracle PL/SQL Programming
Get information about a BFILE
•
•
•
•
Get the name of the file: FILEGETNAME
Get length of the file. GETLENGTH
Does the file exist? FILEEXISTS
Is the file open? FILEISOPEN
Copyright 2010 Feuerstein and Associates
bfile_demo.sql
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Oracle PL/SQL Programming
Read contents of BFILE
DECLARE
l_bfile
BFILE := BFILENAME ('DEMO', 'exec_ddl_from_file.sql');
l_contents
RAW (32767);
l_amount
PLS_INTEGER := 100;
BEGIN
DBMS_LOB.fileopen (l_bfile);
DBMS_LOB.read (l_bfile, l_amount, 1, l_contents);
dbms_output.put_line (l_contents);
DBMS_LOB.fileclose (l_bfile);
END;
• Use DBMS_LOB.READ to read into a RAW or
VARCHAR2 variable.
– But for BFILEs, only RAW.
• You can pass it a BLOB or BFILE pointer.
• The amount is IN OUT – it returns the actual
number of bytes read.
Copyright 2010 Feuerstein and Associates
bfile_read.sql
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Oracle PL/SQL Programming
Other BFILE operations
• Read a BFILE into a BLOB or CLOB.
• Perform INSTR operations on the contents of a
BFILE.
• Perform SUBSTR operations on the contents of
a BFILE.
Copyright 2010 Feuerstein and Associates
bfile_demo2.sql
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Oracle PL/SQL Programming
Conclusions
• Text files can generally be managed with
UTL_FILE.
• When you are working with large, binary files,
however, DBMS_LOB and BFILEs offer a much
better solution.
– Wide range of functionality in the API.
• This lesson serves as an introduction to BFILEs
and DBMS_LOB.
– You will definitely need to study the package more
closely before you start manipulating binary files with
this package.
Copyright 2010 Feuerstein and Associates
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Oracle PL/SQL Programming
Next Steps
• Download the demo.zip if you have not
already (www.ToadWorld.com/SF).
– Run the sample code yourself to better
understand the features and techniques.
• Watch the other lessons in this series.
– Working with UTL_FILE
– System output with DBMS_OUTPUT
– Email with UTL_MAIL
Copyright 2010 Feuerstein and Associates
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