Performance of LOB Segments for Blob Columns

Hi,
I am migrating 11,000 rows of tiff images from Informix to Oracle.In Informix the datatype for the image storage is Byte and Oracle we chose it to Blob.
The Blob column is creating lob segment and lob index.
When I do the migration I observe that the size of the lob segment object is increasing rather than the table object.
So due to creation of this lob segment for the Blob column,will there be any performance issues while retrieval of images from the database and Inserting images into into the database.
Can I get all the issues that can be encountered by storing data in blob column in terms of lob segment.
This is very important information for us as the application has lot of SQL queries for retrieving and injecting images in the database.
It will be really apprecialbe if you can provide Information about this.
Thanks & Regards
Ramanathan KrishnaMurthy

I agree with D.Morgan that object type with 250 attributes is doubtful.
I don't like object tables (tables with "row objects") too.
But, your table is a relational table with object column ("column object").
C.J.Date in An introduction to Database Systems (2004, page 885) says:
"... object/relational systems ... are, or should be, basically just relational systems
that support the relational domain concept (i.e., types) properly - in other words, true relational systems,
meaning in particular systems that allow users to define their own types."
1. How will Oracle store the data in the ADT column?...
For some answers see:
“OR(DBMS) or R(DBMS), That is the Question”
http://www.quest-pipelines.com/pipelines/plsql/tips.htm#OCTOBER
and (of course):
"Oracle® Database Application Developer's Guide - Object-Relational Features" 10g Release 2 (10.2)
http://download-uk.oracle.com/docs/cd/B19306_01/appdev.102/b14260/adobjadv.htm#i1006903
Regards,
Zlatko

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IR Query : select "ROWID","FILE_NAME",dbms_lob.getlength("DATA_FILE") "DATA_FILE",
"DOC_SIZE",PROPOSAL_OWNER
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Hello,
Here you can find a tutorial about blob:
http://www.oracle.com/webfolder/technetwork/tutorials/obe/db/apex/r31/apex31nf/apex31blob.htm
I have a demo here - it shows how to display an image in case the file is image. Otherwise, it displays download link:
http://apex.oracle.com/pls/apex/f?p=63066:1
workspace: somefeto
user: test
pwd: test
Application 63066
Also, there is a packaged application : Sample File Upload and Download that shows you, how to do it.....
you can find it on your workspace.. or here if you wish:
http://apex.oracle.com/pls/apex/f?p=10540:3:15582111009947::NO
workspace: somefeto
user: test
pwd: test
Regards,
Fateh
If you believe that my answer was helpful to you or correct, then please mark the answer as helpful or correct ...

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Hi all,
I wonder if it is possible to declare a blob colum (displayed image) as a link.
What I try to do is to display images in a report and give the user the option to just click on the image an get a popup window where he/she can change or delete the image. As far as I have seen this is not possible with the standard link declaration. You can fill in the link parameters but this has no effect on the generated page.
Thanks
Andy

I eventually found another post: APEX_UTIL.GET_BLOB was not found on this server
In this post there is the suggestion of putting "dbms_lob.getlength("var")" after the date field in your select. So I changed my query to have it at the end, and now my format mask (DOWNLOAD:table_name:ATTACHED_FILE:FILE_ID::FILE_MIME_TYPE:FILE_NAME:::attachment:Download) works like a charm, in a classic report.

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Below is simple Example I tried and output doesnot look right.
Note: My Blob Database Column is "LOGO".
Sample Data Template:
<?xml version="1.0" encoding="WINDOWS-1252"?>
<dataTemplate name="Employee_Listing" description="List of
Employees">
<dataQuery>
<sqlStatement name="Q1">
<![CDATA[SELECT EMPNO,ENAME,JOB,LOGO from
EMP]]>
</sqlStatement>
</dataQuery>
<dataStructure>
<group name="G_EMP" source="Q1">
<element name="EMPLOYEE_NUMBER" value="EMPNO" />
<element name="NAME" value="ENAME"/>
<element name="JOB" value="JOB" />
<element name="LOGO" value="LOGO" />
</group>
</dataStructure>
</dataTemplate>
Sample Ouput Created
<?xml version="1.0" encoding="UTF-8"?>
<EMPLOYEE_LISTING>
<LIST_G_EMP>
<G_EMP>
<EMPLOYEE_NUMBER>999</EMPLOYEE_NUMBER>
<NAME>PILLAI</NAME>
<JOB>MGR</JOB>
<LOGO/>
</G_EMP>
</LIST_G_EMP>
</EMPLOYEE_LISTING>
My Question is :
Does output should have only a TAG for Blob Column or it should have image data
which can be rendered through Template using fo:instream tags.
Am I hitting any bug which is preventing retrieving Blob data through XML data template

I need to get data out of a BLOB column from a table in an Oracle 8i database and into a file that I can put into a MS Word template. The data in the BLOB column came from a MS Word document. What is the best way to proceed? We have a LOB datatype sample which shows how to save a blob from the DB to a local file at http://otn.oracle.com/sample_code/tech/java/sqlj_jdbc/files/advanced/advanced.htm
I'd save it to a temp file and then using word add it. You could also spawn wscript.exe to run a Windows VB Script to automate word from the java application.
Rob

LOB segment size is 2 times bigger than the real data

here's an interesting test:
1. I created a tablespace called "smallblock" with 2K blocksize
2. I created a table with a CLOB type field and specified the smallblock tablespace as a storage for the LOB segment:
SCOTT@andrkydb> create table t1 (i int, b clob) lob (b) store as
t1_lob (chunk 2K disable storage in row tablespace smallblock);
3. I insert data into the table, using a bit less than 2K of data for the clob type column:
SCOTT@andrkydb> begin
2 for i in 1..1000 loop
3 insert into t1 values (mod(i,5), rpad('*',2000,'*'));
4 end loop;
5 end;
6 /
4. Now I can see that I have an average of 2000 bytes for each lob item:
SCOTT@andrkydb> select avg(dbms_lob.getlength(b)) from t1;
AVG(DBMS_LOB.GETLENGTH(B))
2000
and that all together they take up:
SCOTT@andrkydb> select sum(dbms_lob.getlength(b)) from t1;
SUM(DBMS_LOB.GETLENGTH(B))
2000000
But when I take a look at how much is the LOB segment actually taking, I get a result, which is being a total mystery to me:
SCOTT@andrkydb> select bytes from dba_segments where segment_name = 'T1_LOB';
BYTES
5242880
What am I missing? Why is LOB segment is being ~2 times bigger than it is required by the data?
I am on 10.2.0.3 EE, Solaris 5.10 sparc 64bit.
Message was edited by:
Andrei Kübar

thanks for the link, it is good to know such thing is possible. Although I don't really see how can it help me..
But you know, you were right regarding the smaller data amounts. I have tested with 1800 bytes of data and in this case it does fit just right.
But this means that there is 248 bytes wasted (from my, as developer, point of view) per block! But if there is such an overhead, then I must be able to estimate it when designing the data structures. And I don't see anywhere in the docs a single word about such thing.
Moreover, if you use NCLOB type, then only 990 bytes fits into a single 2K chunk. So the overhead might become really huge when you go over to gigabyte amounts...
I have a LOB segment for a nclob type field in a production database, which is 5GB large and it contains only 2,2GB of real data. There is no "deleted" rows in it, I know because I have rebuilt it. So this looks like a total waste of disk space... I must say, I'm quite disappointed with this.
- Andrei

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i am using the code in given link
http://www.oracle.com/technology/oramag/oracle/07-jan/o17odp.html
i chnages that code like this
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JOB_ID VARCHAR2(10 BYTE),
JOB_TITLE VARCHAR2(35 BYTE),
MIN_SALARY NUMBER(6),
MAX_SALARY NUMBER(6),
JOBPIC BLOB
CREATE OR REPLACE PACKAGE associative_array
AS
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TYPE t_job_id IS TABLE OF jobs.job_id%TYPE
INDEX BY PLS_INTEGER;
TYPE t_job_title IS TABLE OF jobs.job_title%TYPE
INDEX BY PLS_INTEGER;
TYPE t_min_salary IS TABLE OF jobs.min_salary%TYPE
INDEX BY PLS_INTEGER;
TYPE t_max_salary IS TABLE OF jobs.max_salary%TYPE
INDEX BY PLS_INTEGER;
TYPE t_jobpic IS TABLE OF jobs.jobpic%TYPE
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p_job_id IN t_job_id,
p_job_title IN t_job_title,
p_min_salary IN t_min_salary,
p_max_salary IN t_max_salary,
p_jobpic IN t_jobpic
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CREATE OR REPLACE package body SHC_OLD.associative_array as
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procedure array_insert (p_job_id in t_job_id,
p_job_title in t_job_title,
p_min_salary in t_min_salary,
p_max_salary in t_max_salary,
P_JOBPIC IN T_JOBPIC
) is
begin
forall i in p_job_id.first..p_job_id.last
insert into jobs (job_id,
job_title,
min_salary,
max_salary,
JOBPIC
values (p_job_id(i),
p_job_title(i),
p_min_salary(i),
p_max_salary(i),
P_JOBPIC(i)
end array_insert;
end associative_array;
this procedure is called from .net. from .net sending blob is posiible or not.if yes how

Ok, that won't work...you need to generate an image tag and provide the contents of the blob column as the src for the image tag.
If you look at my blog entry -
http://jes.blogs.shellprompt.net/2007/05/18/apex-delivering-pages-in-3-seconds-or-less/
and download that Whitepaper that I talk about you will find an example of how to do what you want to do. Note the majority of that whitepaper is discussing other (quite advanced) topics, but there is a small part of it that shows how to display an image stored as a blob in a table.

Should we use LOGGING or NOLOGGING for table, lob segment, and indexes?

We have some DML performance issue on cf contention over the tables that also include LOB segments. In this case, should we define LOGGING on tables, lob segments, and/or INDEXES?
Based on the metalink note < Performance Degradation as a Result of 'enq: CF - contention' [ID 1072417.1]> It looks we need to turn on logging for at least table and lob segment. What about the indexes?
Thanks!

>
These tables that have nologging are likely from the application team. Yes, we need to turn on the logging from nologging for tables and lob segments. What about the indexes?
>
Indexes only get modified when the underlying table is modified. When you need recovery you don't want to do things that can interfere with Oracle's ability to perform its normal recovery. For indexes there will never be loss of data that can't be recovered by rebuilding the index.
But use of NOLOGGING means that NO RECOVERY is possible. For production objects you should ALWAYS use LOGGING. And even for those use cases where use of NOLOGGING is appropriate for a table (loading a large amount of data into a staging table) the indexes are typically dropped (or at least disabled) before the load and then rebuilt afterward. When they are rebuilt NOLOGGING is used during the rebuild. Normal index operations will be logged anyway so for these 'offline' staging tables the setting for the indexes doesn't really matter. Still, as a rule of thumb you only use NOLOGGING during the specific load (for a table) or rebuild (for an index) and then you would ALTER the setting to LOGGING again.
This is from Tom Kyte in his AskTom blog from over 10 years ago and it still applies today.
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:5280714813869
>
NO NO NO -- it does not make sense to leave objects in NOLOGGING mode in a production
instance!!!! it should be used CAREFULLY, and only in close coordination with the guys
responsible for doing backups -- every non-logged operation performed makes media
recovery for that segment IMPOSSIBLE until you back it up.
>
Use of NOLOGGING is a special-case operation. It is mainly used in Datawarehouse (OLAP systems) data processing during truncate-and-load operations on staging tables. Those are background or even offline operations and the tables are NOT accessible by end users; they are work tables used to prepare the data that will be merged to the production tables.
1. TRUNCATE a table
2. load the table with data
3. process the data in the table
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Use of NOLOGGING is rarely, if ever, used for OLTP systems since that data needs to be recovered.

How to show pdf or word icons for a BLOB column in a report?

Hi,
I am getting interested for the blob columns, I have created some columns for storing some pdf drawings and pictures for specific items in a table, it is ok to show a text like 'download' or any other text in the report by setting the following blob attribute:
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Please try using a query like below for your report.
SELECT ticket_details_id,
CASE
   WHEN NVL(dbms_lob.getlength(attachment),0) = 0 THEN NULL
   ELSE
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         WHEN mime_type like '%ms-powerpoint%'
            THEN '<a href="'||apex_util.get_blob_file_src('P101_ATTACHMENT',ticket_details_id)||'" target="_blank"><img src="/i/powerpoint_icon.gif" /></a>'
         ELSE '<a href="'||apex_util.get_blob_file_src('P101_ATTACHMENT',ticket_details_id)||'" target="_blank"><img src="/i/office_icon.gif" /></a>'
      END
END attachment
FROM ticket_details
WHERE ticket_details_id = :P102_TICKET_DETAILS_IDPlease note that I am using APEX_UTIL.GET_BLOB_FILE_SRC function to download the BLOB files. The first parameter of this function in my example query is P101_ATTACHMENT, which refers to page item of type "File Browse" on page 101, which is a DML form on table TICKET_DETAILS. Replace it with the appropriate page number. Please refer to "Working With BLOBs Procedurally" section of this APEX 3.2 documentation for more: [url http://download.oracle.com/docs/cd/E14373_01/appdev.32/e11838/advnc.htm#sthref2199]http://download.oracle.com/docs/cd/E14373_01/appdev.32/e11838/advnc.htm#sthref2199
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http://i39.tinypic.com/2vtbn90.png
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Well that explains the problem. The url NEEDS to be a viable url to an image -- a procedure needs to be called to (in essence) spit out the blob to a mime-type of jpeg so the browser can display it. Although there are several ways to achieve this -- since you basically see it "working in one place but not another", take a look at how the working image's URL is generated on the page where it's working.. APEX offers an item type that can display an image, but you can also use PLSQL code to insert such in the rendered output anywhere. If none of this helps, there are many hits via google that discuss all of this in the detail you'll need.

I have a question for you: Inserting Word document in BLOB column

Hey Experts,
I have found a good info and a sample on how to achieve this on
http://www.sys-con.com/java/source/5-6/code.cfm?Page=76.
declare
f_lob bfile;
b_lob blob;
begin
insert into sam_emp(empno,ename,resume)
values ( 9001, 'Samir',empty_blob() )
return risumi into b_lob;
f_lob := bfilename( 'MY_FILES', 'MyResume.doc' );
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dbms_lob.loadfromfile
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dbms_lob.fileclose(f_lob);
commit;
end;
I have a jsp project and the users ( on the client side)must be
able to create a word document and send it to the server with an
uplaod servlet. With another servlet or jsp i want to process
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The option should be visible here: http://support.mozilla.com/en-US/kb/Printing%20a%20web%20page#w_print-window-settings
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* Select '''Selection''' to print only the part the page you've highlighted.
Does it work for you?

DOES 9i OAS perform CMP for BLOB types?

DOES 9i OAS perform CMP for BLOB types? Perhaps more on an OAS question, but anyone have experience using CMP to persist anythin other than simple types? Any one try BLOBs intermedia types?
Thanks

I assume you mean 9iAS...
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Hi friends,
(Forms 6i)
I have a .pdf into a blob column and I want to show that .pdf as my report output...
Example-> The report only have this query:
select myblob_ column
from mytable
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Thanks.
Jose.

Hello,
How has been "uploaded" the PDF file in the BLOB ?
Regards

Performance of LOB Segments for Blob Columns

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