LOBS, BLOBS, CLOBS: Dealing with Attachments in APEX

@sthilaire wphilltech.com

LOBS, BLOBS, CLOBS
Dealing with Attachments in APEX
Tim St. Hilaire
Feb 2014


The Plan
•
•
•
•
•
•
•

Intro
The Goal
APEX BLOB Wizard
Making It Your Own
Base Technology
Advanced Database Concepts
Questions


Introduction
Tim St. Hilaire
• System Integrator
• Problems Solver
• Pragmatist
• Technology Enthusiast
• APEX Fan
• Enkitec Product Developer


The Goal
• Ability to accept file attachment input from
users in an application
• Use the content in applications either as text,
images, or downloadable to users
• Understand how the data is stored, retrieved,
and managed inside the database


Demonstration – The Goal


The Academics


The Academics
• LOB – Large Objects – broken down into
datatypes
– BLOB - Stores unstructured binary data in the
database as a bit stream
– CLOB – Stores large amounts of text such as XML in
the database character set
– NCLOB – National Character Set LOB – stores Unicode
data
– BFILE – external LOB
– Secure File LOB – file data enabling advanced features
such as compression and encryption


BLOB vs. CLOB
• BLOB
– Stream of data intended to be binary
– Chunks are returned in RAW format (substr)

• CLOB
– Will translate between character sets
– Chunks are returned in VARCHAR2 format (substr)

SELECT * FROM
NLS_DATABASE_PARAMETERS WHERE
PARAMETER = 'NLS_CHARACTERSET';


There are 10 types of people in the world…
Those that understand binary, and those that
don’t.
-- The Internet


APEX


Demonstration - APEX Submit Button


Where did the file go?
WWV_FLOW_FILES
APEX_APPLICATION_FILES


Table Context Sensitivity
• APEX_APPLICATION_FILES – limits to files
available in the workspace.
• Includes files that were uploaded by all
applications in a workspace
• Includes files that have been uploaded via the
builder
• Includes Static Shared Component Files for the
Application and the Workspace


Evaluate WWV_FLOW_FILES
Pros
• No Table Creations Required
• Consistent Implementation
• Storage in a known location

Cons
• Need Remote Key Storage
• Application Files combined
• Storage for all Workspaces
is shared
• Some Files are publicly
available


Custom Table


My Table
• To configure your own table
• Minimum Requirements
• Adjust to Features and Business Requirements

ID
ACTUAL_FILE
MIME_TYPE
FILE_NAME

NUMBER (your choice)
BLOB
VARCHAR2
VARCHAR2


Custom Table
CREATE TABLE MY_APEX_FILES(
BLOB_ID
NUMBER NOT NULL,
NAME
VARCHAR2(100 BYTE),
DESCRIPTION
VARCHAR2(2000 BYTE),
CATEGORY
VARCHAR2(200 BYTE),
PUBLIC_FLAG
VARCHAR2(1 BYTE),
BLOB_CONTENT
BLOB,
BLOB_SIZE
NUMBER,
MIME_TYPE
VARCHAR2(255 BYTE),
FILE_NAME
VARCHAR2(255 BYTE),
CREATED_BY
VARCHAR2(50 BYTE),
CREATED_ON
DATE,
UPDATED_BY
VARCHAR2(50 BYTE),
UPDATED_ON
DATE);


Referencing


Form - File Browse Settings


Form - Display Images


Form - Difference
<img id="P210_IMAGE"
src="apex_util.get_blob_file
?a=500&s=9700348909
98301&p=210&d=
27553826455759041&i
=27566106354076381&amp
;p_pk1=3212306414813867
83828770868593367722825
&p_pk2=&p_ck=D
164075B30411E1CF29B6B9
ED9A57684" alt="Hunger"
title="Hunger">

<img
id="P210_IMAGE_SELECT"
src="wwv_flow.show?p_req
uest=NATIVE%3DC825C6CF6
97537EC53FBD9065B8B082
7585481276038A327CEF5A
150CAC67389&p_insta
nce=970034890998301&am
p;p_flow_id=500&p_fl
ow_step_id=210">


Report - Showing Contents


Report – BLOB Field
• When writing SQL, the report column is NOT
the BLOB content Field – as much as a
reference to the content


Report – Numbers Required
• The Report column is calculated as SIZE
• Using the APEX format mask / generator, it
must be a number.


Report Content = SIZE
• Note – You can store the size when the row is
written for easy syntax


Notes From the Field
• The Mime Type and File Name is important for
usability


• The report column containing the primary key
must be named the same as the primary key
field in the BLOB table – even if the BLOB table
is not in the report
• Fields are ignored based on format selections
(inline vs. download)


Report - Include Download


Link Creation Result
<a
href="apex_util.get_blob?s=8634949024800&a
mp;a=500&c=3473415610798872&p=
200&k1=3418001856547833&k2=&a
mp;ck=BD47E34C8E5A3058299ECD457A4574B4
&rt=IR" alt="Download"
title="Download 58KB">Download</a>


• Case Sensitive Names
“Apex_application_files”
!=
APEX_APPLICATION_FILES


Report - Include Image


Report - Include Image
As a Column in a Select Statement:
CASE
WHEN MIME_TYPE LIKE 'image%' THEN
'<img
src="'||apex_util.get_blob_file_src
(
'P210_BLOB_CONTENT',ID)||
'" height="75" width="75" />'
ELSE NULL
END as shrunk


Text


Quiz
(A)
(B)
(C)
(D)
(E)
(F)

What is the size limit of a VARCHAR2?
255
2000
4000
32767
8 Terabytes
Whatever it is defined as….


Maximum Width


Rich Text Editor
Character Limit!
Or
The most descriptive error messages ever…


Demonstration – Text Region Error


Plugin – Rich Text


The Next Level of Complexity


Once Upon a Time….
@apexins.sql

@apexins.sql

Tablespace_apex

SYSAUX

tablespace_files

SYSAUX

tablespace_temp

TEMP

images

/i/


Specify LOB Storage Location
CREATE TABLE ContainsLOB_tab (
n NUMBER,
c CLOB)
lob (c) STORE AS BASICFILE segname
(TABLESPACE lobtbs1
CHUNK 4096
PCTVERSION 5
NOCACHE LOGGING
STORAGE (MAXEXTENTS 5)
);


Demonstration – Text Region Plugin


Size of Tables
SELECT
l.table_name||'-lob',
s.bytes
FROM user_lobs l,
user_segments s
WHERE
s.segment_name = l.segment_name
AND
s.segment_type = 'LOBSEGMENT'


Size Matters
ALTER TABLE MY_TABLE DEALLOCATE UNUSED;
ALTER TABLE MY_TABLE enable ROW MOVEMENT;

ALTER TABLE MY_TABLE SHRINK SPACE cascade;
ALTER TABLE MY_TABLE disable ROW MOVEMENT;

Find a DBA to Partner With


Questions and Comments


References
Many thanks to all those that have come before me, and for those that take the time to help others grow and
improve their skills by sharing their time an knowledge.

•

Enkitec Plugin
– http://www.enkitec.com/products/plugins

•

Demonstration Application
– http://wphilltech.com

•

APEX Docs
– BLOB in APEX 17.10
http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35125/advnc_blob.htm#HTMDB25906
– GET_BLOB_FILE_SRC
http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35127/apex_util.htm#AEAPI129

•

DBMS_LOB
– http://docs.oracle.com/cd/E11882_01/appdev.112/e25788/d_lob.htm

•

Oracle SecureFiles and Large Objects
– http://docs.oracle.com/cd/E11882_01/appdev.112/e18294/adlob_tables.htm
– http://docs.oracle.com/cd/E11882_01/appdev.112/e18294/adlob_lob_ops.htm

•

APEX Builder - BLOB Support in Forms and Reports
– http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35125/advnc_blob.htm

•

Icons
– http://www.stdicon.com/


Disclaimer
• Marks, images, brands and referenced content are the
property of their respective owners. Usage is for
discussion purposes only. No ownership assumed or
implied.
• The comments and opinions expressed here are sole
responsibility of the author and not of his employer or
any other party.
• No trees were harmed during the creation of this
presentation. However, a great number of electrons
were terribly inconvenienced.

LOBS, BLOBS, CLOBS: Dealing with Attachments in APEX

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