Oracle in World: June 2009

Monday, June 29, 2009

How to know which objects are being accessed by a user

You can track what users are doing currently in the database. You can get the object name as well as the operating system user name, the host name, the type of objects they are accessing and many more.

Below is the query. You can query from more columns if you like. Also to run the query you need access to the v$access and v$session view.

In the example I have shown what user TEST1 and TEST2 is doing in the database.


SQL> SET LINESIZE 200
SQL> SET VERIFY OFF
SQL> COL object FOR A30
SQL> SELECT a.object,
 2         a.type,
 3         a.sid,
 4         b.username,
 5         b.osuser,
 6         b.program
 7  FROM   v$access a
 8  JOIN   v$session b ON (a.sid = b.sid)
 9  AND    a.owner = UPPER('&SCHEMA') ORDER BY a.object;
Enter value for schema: TEST1


OBJECT                         TYPE             SID USERNAME     OSUSER             PROGRAM
------------------------------ ---------        ---- ---------- ------------------ ------------
DBMS_APPLICATION_INFO          CURSOR           149 TEST2        ARJUPC\Arju       sqlplus.exe
DUAL                           CURSOR           159 TEST1        ARJUPC\Arju       sqlplus.exe
DUAL                           CURSOR           149 TEST2        ARJUPC\Arju       sqlplus.exe
TAB1                           TABLE            159 TEST1        ARJUPC\Arju       sqlplus.exe

SQL> /
Enter value for schema: TEST2


OBJECT                         TYPE          SID USERNAME     OSUSER             PROGRAM
------------------------------ ----------- ---------- ------------ ------------------ ------------
T                              TRIGGER       159 TEST1        ARJUPC\Arju       sqlplus.exe
TAB1                           TABLE         159 TEST1        ARJUPC\Arju       sqlplus.exe

SQL>

USB Flash drive Reviews.

The term USB means Universal Serial Bus. As the name Serial Bus indicates USB is a standard to send data one bit at a time, which means it communicates via serial communication or in other word data is send sequentially. USB can connect computer peripherals such as mice, keyboards, PDAs, joysticks, scanners, digital cameras, printers, modems, mobile phones, personal media players, bluetooth devices, flash drives, as well as external hard drives. Now all USB drives become so popular and almost all new computers have more than one USB port.

Out of USB drives the flash drive or keychain drive or also called jump drive is a plug-and-play portable storage device. In this country (Bangladesh) we call it pen drive. USB flash drive allows hot swapping after we attach it to any computer we don't need reboot the machine. Without reboot we can work with it. Unlike other removable storage USA flash drive does not require batteries or an external power supply. It also is not platform dependent. With data transfer and storing facility many manufacturers offer various types of function such as password protection, and downloadable drivers that allow the device to be compatible with older systems that do not have USB ports.

USB flash drives become very much popular device now a days because of it's

1)Storage capacity- which allows 64M to 128G data stored capacity.

2)Cheaper- think about why we don't use floopy drive. With storing capacity of 1.44M floppy drive how much we would need to pay to get 1G space and how much space in our room they would occupied? Simply a 25 gram weighted flash drive can do full fill everything.

3)Faster- Pen drive is much faster than Floppy drive, CD.

4)Durable- Many companies offers life time warranty of flash drive unlike hard disk or any other storages.

Most flash drives ship preformatted with the FAT or FAT 32 file system unlike hard disk which comes as RAW partitions. The reason to ship with FAT or FAT32 is because of the ubiquity of these file systems. These file system allows the drive to be accessed on virtually any host device with USB support.

Whenever you compare between two USB drives then it comes several aspects.

1)Product Features: This usually refers to the read and write speeds of the USB drives in addition to other features, such as a retractable USB connector or swivel cap, whether the device is water resistant and whether it comes with accessories.

2)Included Software: Which software usually comes with the USA flash drive. It may be security programs, sync tools and virtual application platforms.

3)Value: To measure the value of a USB drive take into account the price of the flash drive compared to how much storage space it offers.

4)Warranty/Support: Many people rely on this feature. In fact I myself always look for it. Many manufacturers offer life time warranty for their flash drives.

5)Size/Design: Many USB flash/jump drives come with attractive design. You can choose them if you want look and feel to be good.

You can also get your custom flash/jump drive. You can see many sites that offer custom jump drive and through them you can make a custom drive for your requirement and look and feel.

Related Documents

Debit Card, Credit Card, ATM Card, Charge Card

Debit Card:
---------------------
A Debit card provides an alternative payment method to cash when making purchases. Its functionality is more similar to writing a cheque as the funds are withdrawn directly from either the bank account (often referred to as a cheque card), or from the remaining balance on the card.

In some countries the debit card is multipurpose, acting as the ATM card for withdrawing cash and as a check guarantee card. Merchants can also offer "cashback"/"cashout" facilities to customers, where a customer can withdraw cash along with their purchase.

Credit Card:
----------------------
A credit card is a system of payment issued to users of the system. In the case of credit cards, the issuer lends money to the consumer (or the user) to be paid later to the merchant. It is different from a charge card, which requires the balance to be paid in full each month. In contrast, a credit card allows the consumer to 'revolve' their balance, at the cost of having interest charged.

For consumers, the difference between a "debit card" and a "credit card" is that the former immediately deducts the balance from a checking or savings account, whereas in the case of creadit card it allows the consumer to spend money they might not actually have (but promise to pay later to the card-issuing bank).

Many companies offer credit cards and you can apply credit cards online. It can be categorized to into student credit cards, bad credit credit card, and secured cards. From google you can see many sites that do Credit Card Offers.

ATM Card:
---------------
An ATM card (also known as a bank card, client card, key card or cash card.
It can be used:

-at an ATM for deposits, withdrawals, account information, and other types of transactions, often through interbank networks

Some ATM cards can also be used:

-at a branch, as identification for in-person transactions
-at merchants, for EFTPOS (point of sale) purchases

Unlike a debit card, in-store purchases or refunds with an ATM card can generally be made in person only, as they require authentication through a personal identification number or PIN. In other words, ATM cards cannot be used at merchants that only accept credit cards.

However, other types of transactions through telephone or online banking may be performed with an ATM card without in-person authentication. This includes account balance inquiries, electronic bill payments or in some cases, online purchases.

In countries that don't have distinct debit cards (pure ATM cards without debit card function), such as Canada, an ATM card is also known as a "debit card".

Charge Card:
------------------
A charge card is a means of obtaining a very short term (usually around 1 month) loan for a purchase. It is similar to a credit card, except that the contract with the card issuer requires that the card holder must each month pay charges made to it in full -- there is no "minimum payment" other than the full balance. Since there is no loan, there is no official interest. A partial payment (or no payment) results in a severe late fee (as much as 5% of the balance) and the possible restriction of future transactions and risk of potential cancellation of the card.

An example of ORA-01536 when quota exhaust on dependent objects

I am inspired to write this topic after getting a post inside the forum http://arju-on-it.com/blog/forum/server-administration/ora-01536-space-quota-exceeded-for-tablespace-mon_tbs.
In the example I have shown the reason why ORA-01536: space quota exceeded for tablespace error comes.

In this post I will give you the example when ORA-01536 occurs due to the dependent object on the table.
1)Create user test1 and grant unlimited quotes on default tablespace.
SQL> create user test1 identified by t default tablespace users;

User created.

SQL> grant create session, create table to test1;

Grant succeeded.

SQL> alter user test1 quota unlimited on users;

User altered.

2)Create user test2 and grant 1M quota.
SQL> create user test2 identified by t default tablespace users;

User created.

SQL> grant create session, create table, create trigger to test2;

Grant succeeded.

SQL> alter user test2 quota 1M on users;

User altered.

3)Create a table inside test1 schema.

SQL> conn test1/t
Connected.

SQL> create table tab1 as select level a1, level a2 from dual connect by level <10;

Table created.

SQL> conn test2/t
Connected.
SQL> create table tab1 as select level a1, level a2 from dual connect by level <1;

Table created.

SQL> conn test1/t
Connected.
SQL> grant select on tab1 to test2;

Grant succeeded.

5)Create a trigger inside test2 schema which inserts based on test1 insert.
SQL> conn / as sysdba
Connected.

SQL> create or replace trigger test2.t after insert on test1.tab1
2 begin
3 insert into test2.tab1 select * from test1.tab1;
4 end;
5 /

Trigger created.

6)Connect to test1 and insert more rows.
SQL> conn test1/t
Connected.

SQL> insert into tab1 select level a1, level a2 from dual connect by level <100;

99 rows created.

SQL> insert into tab1 select level a1, level a2 from dual connect by level <10000;

9999 rows created.

SQL> insert into tab1 select level a1, level a2 from dual connect by level <100000;
insert into tab1 select level a1, level a2 from dual connect by level <100000
*
ERROR at line 1:
ORA-01536: space quota exceeded for tablespace 'USERS'
ORA-06512: at "TEST2.T", line 2
ORA-04088: error during execution of trigger 'TEST2.T'

7)Log on as dba user and check for dependent objects. Grant quota of the owner of the dependent objects tablespaces.

SQL> conn / as sysdba
Connected.

SQL> select NAME,TYPE, OWNER from dba_dependencies where REFERENCED_NAME='TAB1' AND
2 REFERENCED_OWNER='TEST1';

NAME TYPE OWNER
------------------------------ ----------------- ------------------------------
T TRIGGER TEST2

See trigger definition and as trigger inserts into TAB1 table which resides in USERS tablespace so grant more quote to TEST2 user on tablespace USERS.

SQL> ALTER USER TEST2 QUOTA 10M on USERS;

User altered.

SQL> conn test1/t
Connected.

SQL> insert into tab1 select level a1, level a2 from dual connect by level <100000;

99999 rows created.

And it is ok now.

Sunday, June 28, 2009

How to add a word or letter at the end of each line in shell script

Let's use student.txt as below and now we want to add "Std_ID;" on each line in the student.txt of course without double quote.
$ cat student.txt
024434
022403
021437

1)Using sed -i:

$ sed -i 's/$/ Std_ID;/' student.txt

The s means substitute
The $ in this particular regex (regular expression) means end of the line.
The " Std_ID;" is the substituting word.

$ cat student.txt
024434 Std_ID;
022403 Std_ID;
021437 Std_ID;

2)Simple sed command.
$ cat student.txt
024434
022403
021437

$ sed 's/.*/& Std_ID;/' student.txt
024434 Std_ID;
022403 Std_ID;
021437 Std_ID;

3)Using awk:
$ cat std.txt
024434 Std ID
022403 Std ID
021437 Std ID

$ awk '{print $0," Std_ID;"}' student.txt>std.txt

$ cat std.txt
024434 Std_ID;
022403 Std_ID;
021437 Std_ID;
Related Documents
How to add a line to the first in a file using shell script

Input-Output rediection on linux

Data manipulation using awk utility in linux

Edit file on linux using sed utility

Saturday, June 27, 2009

Arju On IT lanuched.

I have a great news to share with you that about 3 days ago Website Arju On IT is launched. And I just add a forums there today at 27th June 2009. I will request you to participate there any types of IT related activities starting from Operating System, any hardware issue, programming, web developing, web design, database issue etc.

The home page of the site is now at http://arju-on-it.com/ and the forum is now on http://arju-on-it.com/forum. The forum is divided into several categories. At first register there and put your relevant posts into relevant topics.

It is very simple to register there. Just you need to fill up only username and email plus a simple math. Your password will be sent to your email address and then you can change anytime as you wish. Also any types of feedbacks and suggestion in the forum is really welcome.

I hope this site also will do well even more than my blog http://arjudba.blogspot.com.

Pray for me.

Tuesday, June 23, 2009

How to add a line to the first in a file using shell script

There are many ways and techniques to add a line to the first inside a file using shell script. In this post I will discuss some ways.

Let's start with a file to which we will do operation. Name the file as student_info.txt and it contains following data.
$ cat >student_info.txt
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

We are making a copy of student_info.txt so that orginal file is intact and we can play with copying file.

$cp student_info.txt student.txt

Each time we will test on student.txt and then before starting to test another way we will overwrite student.txt by student_info.txt

Note that after cat and ">" sign you can insert data and whenever you finish just press CTRL+D.
Now in the first line of the student_info.txt file I like to add header information in the way, "StdID|Full Name|Department". Several techniques are shown below.

$ cat student.txt
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

1)Using echo, cat, mv method:
This is the simplest method to do the job. In a new file write one line and then append the contents of original file to the new file. Move new file to original one.


$ cat first_method.sh
echo "StdID|Full Name|Department" >student_temp.txt
cat student.txt>>student_temp.txt
mv student_temp.txt student.txt

$ ./first_method.sh

$ cat student.txt
StdID|Full Name|Department
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

2)Using sed command:
$ cp student_info.txt student.txt
With inline based sed command you can either directly modify within file and insert a line to the first or you can take a backup before modifying.

Directly add a line to the header using sed by,
$ sed -i '1iStdID|Full Name|Department' student.txt

$ cat student.txt
StdID|Full Name|Department
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

Before adding line you can create backup file of the original one named student.txt~ using,

$ cp student_info.txt student.txt

$ sed -i~ '1iStdID|Full Name|Department' student.txt

$ cat student.txt~
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

$ cat student.txt
StdID|Full Name|Department
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

3)echo, cat, mv in one line:
$ cp student_info.txt student.txt

Note that if with the cat option no filename is provided, or when FILE is -, then it read standard input. So writing echo "StdID|Full Name|Department" |cat - student.txt will be the desired output and then we redirect output to a file and then move temp with original one.

echo "StdID|Full Name|Department" |cat - student.txt>student.tmp && mv student.tmp student.txt

$ cat student.txt
StdID|Full Name|Department
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

4)Using perl -i:
With perl -i command you can do the job easily. Note that if you use .bk then it will backup your original file.

perl -i.bk -pe 's/^/StdID|Full Name|Department\n/ if($.==1)' student.txt

5)Using awk:
$ cp student_info.txt student.txt

$ cat student.txt
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

$ awk 'NR==1{print "StdID|Full Name|Department"}1' student.txt>student.tmp

$ cat student.tmp
StdID|Full Name|Department
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

5)Using echo -e and cat command:
$ echo -e "StdID|Full Name|Department\n$(cat student.txt)">student.txt

$ cat student.txt
StdID|Full Name|Department
024401|Mohiuddin Rafi|CSE
024201|Mohammad Raju|MCE
024101|Mohammad Jamil|EEE

Related Documents

Introduction -What is kernel, shell, shell script.
Basic Steps to write a shell script
Variables in shell script
Output text with echo command

Input-Output rediection on linux

Data manipulation using awk utility in linux

Edit file on linux using sed utility

How to see directory contents, file size, file type, modification date using php

There is already some raw output of directory contents which is shown in the post List of directory contents using array in php. In this post I will display the directory contents into more readable format as well as the contents size, file type and modification date of the file/folder.

We will start by making a hard code directory in our code to which contents file type, size will be displayed.

1)We assign the directory location to a path so that we can work further with this $path variable.
$path='D:/test';

2)You need to open the directory using php opendir() function.
$myDirectory = opendir($path);

3)Using a while loop read each directory contents and put them into an array variable named $dirArray.
while($entryName = readdir($myDirectory)) {
$dirArray[] = $entryName;
}
4)As we already read all the contents and the contents are within array variable so now we can close the directory using,
closedir($myDirectory);

5)We need to count the number of elements inside the array, in order words number of files exist inside the operating system directory.
$indexCount = count($dirArray);

6)Optionally we are sorting here so that we can display them in an order.
sort($dirArray);

7)As you have seen in the example http://arjudba.blogspot.com/2009/03/list-of-directory-contents-using-array.html [0] => . [1] => .. are there and you might not want to display those hidden contents. So before displaying contents you will check whether filename starts with a dot (.) . If it starts with a dot file will not be displayed on the browser. Simply using if condition we can omit it.
if (substr("$dirArray[$i]", 0, 1) != ".")

8)To display all files in the array we can use for loop construct.
for($i=0; $i < $indexCount; $i++) Now the above php lines are combined and embedded with html in order to display result in a good format. Full code is below.


<?
$path='D:/test';
// open this directory
$myDirectory = opendir($path);

// get each entry
while($entryName = readdir($myDirectory)) {
 $dirArray[] = $entryName;
}

// close directory
closedir($myDirectory);

// count elements in array
$indexCount = count($dirArray);

// sort them
sort($dirArray);
?>

<html>
<body>
<table style="margin-bottom: 1px;" border="0" cellpadding="6" cellspacing="1" width="90%">
      <tbody>
  <tr>
      <th class="TableData" style="padding-left: 11px; padding-right: 1px;"
  bgcolor="#dadce1" width="300" height="22">File Name
      </th>
     
      <th class="TableData" style="padding-left: 11px; padding-right: 1px;"
  bgcolor="#dadce1" width="100" height="22">File Size
      </th>
     
  <th class="TableData" style="padding-left: 11px; padding-right: 1px;"
  bgcolor="#dadce1" width="350" height="22">Date Modified
      </th>
     
  <th class="TableData" style="padding-left: 11px; padding-right: 1px;"
  bgcolor="#dadce1" width="110" height="22">File Type
      </th>
 
  <?
  for($i=0; $i < $indexCount; $i++) {
  // don't list hidden files
  if (substr("$dirArray[$i]", 0, 1) != "."){

  ?>

  <tr>
     <td class="Lebels" align="right" bgcolor="#e9ece9" >
  <? echo $dirArray[$i]; ?>  
  </td>
  <?
  print("<td bgcolor=\"#e9ece9\">");
  # We may want a file size. Note that you need to add path
  if( filesize( $path . "/" . $dirArray[$i] ) >= 1024 ) {
   # Size in kilobytes
   print " " . round( filesize( $path . "/" . $dirArray[$i] ) / 1024, 1 )
   . " K<br />\n";
  } elseif( filesize( $path . "/" . $dirArray[$i] ) >= 1048576 ) {
   # Size in megabytes
   print " " . round( filesize( $path . "/" . $dirArray[$i] ) / 1024 / 1024, 1 ) . " M<br />\n";
  } else {
   # Size in bytes
   print " " . filesize( $path . "/" . $dirArray[$i] ) . " bytes<br />\n";
  }
  print("</td>");
  ?>
      
  <td class="Values" bgcolor="#e9ece9" ><? echo date ("F d Y H:i:s.", filemtime($path . "/" . $dirArray[$i])); ?>
  </td>

  <td class="Values" bgcolor="#e9ece9" >
  <? print(filetype($path . "/" . $dirArray[$i] ));?>
 
  </td>
  </tr>
  <?
 }
}

print("</TABLE>\n");
?>
</body>
</html>

A sample output in my system of the above output is,

File Name	File Size	Date Modified	File Type
Accounts.txt	297 bytes	December 21 2008 16:26:39.	file
Ghor_Kutum_16.wmv	23232.6 K	February 08 2009 11:12:36.	file
New Folder	0 bytes	June 23 2009 14:58:47.	dir
SPFILEORCL.ORA	3.5 K	May 16 2009 06:26:53.	file
a.txt	51 bytes	May 16 2009 06:16:28.	file
database_dump.txt	10.9 K	June 19 2009 11:09:30.	file
database_testprotege_profile.csv	1.7 K	June 20 2009 16:50:32.	file
zwt-escep310.rar	1089.7 K	December 13 2008 08:38:16.	file

Monday, June 22, 2009

Free Online scan for viruses, trojans, worms and other exploits

As many of you may know, website/online viruses are increasingly common over the Internet and it won't take much till you have your computer infected if you don't pay attention or you have an older browser that is easily exploitable.

Before starting into online scan let's have an idea about the term computer virus, trojans, worms etc.

A computer virus is a computer program which creates copy of itself and spread all over computer as well as infect a computer without the permission or knowledge of the owner. It can damage useful file as well. Many one use the term virus commonly for malware, adware, and spyware programs but this is wrong. Virus has reproductive ability but malware, adware, and spyware do not have.

Trojan horses are a huge security threat. A Trojan is a program that enters your computer undetected, giving the attacker who planted the Trojan unrestricted access to the data stored on your computer. Trojans can delete file, modify file, upload file, download file, even install software and do keystroke logging. It can transmit credit card information and other confidential data in the background.

Worm threat causes consuming network bandwidth. Worm itself is replicated and send the copy of itself to another computer over the network. There may some scenarios whenever you see your network, may be even network is horribly slow but and it consumes almost 100% bandwidth which possibly caused by worm.

As these problem became increasingly disturbing, some companies started creating databases with lists of infected sites and popular browsers like Firefox nowdays make use of such lists in order to prevent you from visiting an infected site.

Anyway, though these kind of things are absolutely welcome I couldn't find till now an online, real time virus/malware scanner that will tell me if a site is infected and how I could actually clean it.

So, if you are a website owner and want to online scan your site for viruses then you can have a look at http://tools.geek-tools.org/en/online-scan.

Then if you are unlucky enough to discover that your site is infected then from google you can check out instructions by searching keywords "clean your site" in google.com.

Related Documents

Sunday, June 21, 2009

DDL with the WAIT option in 11g -DDL_LOCK_TIMEOUT

Whenever you perform any DDL operation on a table, oracle try to lock the table exclusively. In oracle version 10g and earlier, whenever you issue DDL, oracle try to lock the table exclusively with NOWAIT option and if it fails then immediately "ORA-00054 resource busy and acquire with NOWAIT specified" error returned. In fact, in oracle 10g we didn't have any other alternatives. So we had to wait until resource is free and in fact in production database you might need hours to complete your DDL jobs and you might need to try it frequently to test when resource become free.

A discussion about ORA-54 error with an example is demonstrated in the topic ORA-00054: resource busy and acquire with NOWAIT specified.

Oracle database 11g includes the DDL_LOCK_TIMEOUT parameter, which you can set using the ALTER SYSTEM and ALTER SESSION commands. Now you have the opportunity not to issue DDL frequently and query itself can wait a specified time and if it find resource free within this time DDL operation will be completed.

The parameter DDL_LOCK_TIMEOUT specifies a time limit for how long DDL statements will wait in a DML lock queue.
- The default value is zero which indicates a status of NOWAIT.
- The maximum value is 1,000,000 seconds which indicates the DDL statement will wait forever to acquire a DML lock.
- If you specify time in the DDL_LOCK_TIMEOUT parameter and if a lock is not acquired before the timeout period expires, then an error is returned.

To demonstrate this scenario let's create a simple example in oracle database 11g.

1)Create table named test_wait, insert a row and leave the session alone.

SQL> create table test_wait(col1 number);

Table created.

SQL> insert into test_wait values(1);

1 row created.

2)Now from another session do DDL operation.
Note that you may be succeed while adding column to the table in this case. Here in another session I am practising DROP DDL command.

SQL> drop table test_wait;
drop table test_wait
*
ERROR at line 1:
ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired

SQL> show parameter ddl_lock_

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
ddl_lock_timeout                     integer     0

It failed because in the above you see ddl_lock_timeout is set to 0 which means NOWAIT and so if query see someone lock the row error returned immediately.

Now we change to parameter to 100. Now query will wait for 100 seconds in order to see whenever resource become free.

SQL> alter session set ddl_lock_timeout=100;

Session altered.

Now in the first session issue commit.
SQL> commit;

And in the second session try to drop the table and you see drop become successful if you do commit within 100 seconds.
SQL> drop table test_wait;

Table dropped.

However if you did not do commit within 100 seconds in the first session then after 100 seconds in the second session DROP command would fail with "ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired".

Related Documents
http://arjudba.blogspot.com/2009/01/ora-00054-resource-busy-and-acquire.html
http://arjudba.blogspot.com/2009/06/new-features-in-oracle-database.html

New features in Oracle database administration in 11g
DDL with the WAIT option in 11g -DDL_LOCK_TIMEOUT

http://arjudba.blogspot.com/2009/11/ora-01012-not-logged-on.html

http://arjudba.blogspot.com/2008/07/process-and-runtime-limits.html
http://arjudba.blogspot.com/2008/04/user-resource-limits-in-oracle.html

http://arjudba.blogspot.com/2008/07/classes-of-oracle-wait-events.html

http://arjudba.blogspot.com/2008/05/what-is-enq-tx-row-lock-contention.html

How to get targeted backlinks to your site

Before starting this post let's have an idea what is called back link. Back links are the incoming links to a website or a web page. Backlinks mean any links that is received by a website from another web node.

The more you have back links, the more you have the possibility to visit your website or a web page. Also in the search engine optimization world, backlinks are the important measure to indicate the popularity or importantance of a web page. In fact backlinks are one of the important measure to build google pagerank (which indicates how important a web page is). In order word you can say the more you have backlinks, the more possibility of google to display your web page link in the first page.

Backlinks are also named as incoming links, inbound links, inlinks, and inward links.

If you ask for an example of backlinks then on the Arju on IT you see within the recommended links there is my site url link "Arju’s Old Blog". So that one is the backlink of http://arjudba.blogspot.com/.

Now a question is how to get backlinks to your site. There is many ways to get backlinks in your site.

A) Check for competitive site backlinks and submit your links to there.
Many of them here's a pretty straight forward way to get relevant links to your sites.

This method is not a "revealed secret" nor will it guarantee your site first position on Google or other search engines :-)

Though, this method will bring you good results considering you have time and persistence to do it on a regular basis.

Here's the whole idea in a phrase: figure out what is your competition, check their sites for traffic, location and backlinks and try add your own backlinks to the sample places where your competition added theirs already.

Let's consider Arju's blog is our competitor site. So,

1) check where backlinks for arjudba.blogspot.com come from using Site info for Arju's blog and to see backlinks using See backlink of arjudba. You can also see competitive site using Google trends and check the "Also Visited" column.

2) In a new tab open http://seopro.com.au/free-seo-tools/link-checker, type in competitor site (e.g. arjudba.blogspot.com, mysubtitles.com, nowsubtitles.com etc)
Check the Homepage PR, Links count, Nofollow, Anchor box and in a couple of minutes you'll start seeing where the competition gets the backlinks from.

3) Make sure you select only the backlinks that do not have the rel="nofollow" tag and then:
- From any page rank checker or from google page rank check add on check Page Rank for that URL
- From http://tools.geek-tools.org/en/site-traffic you can check estimated site traffic for it
- and from http://tools.geek-tools.org/en/dns-lookup check DNS Lookup tool and see in what country is that site located.

You'll need this info so you can find the best pages for your backlinks which are the pages with highest page rank, highest traffic and if possible hosted on a server in the same country as your intended audience.

B) Write articles to many sites and embed you site url as signature.
You can choose high page rank site related to your website to write articles and then at the end you can use your site link as a signature. So you are getting backlinks from the signature.

C) Write blog articles and submit the link to your social bookmarking site.

D) Post comments in other people's blogs that are related to the subject to your posting link. Note that post only in blogs that allow you to admit a link back to your blog or website as some blogs don't allow html link.

E) Post your site url to several forums

You can join several forums and participate in discussion and at the end of the post add a signature that points to your web page.

F) Some website allow you to trade links which is known as reciprocal linking. In this case you are bound to post other site's link and other site will post your link as well.

G) You can purchase ads from site. A site will put a static ads in their site and the site in turn archive the page but don't remove the ads.

H) Purchase text links ads on other people's blogs. If you get on a blog sidebar your link can end up on thousands of pages giving you massive exposure with one link. For example I take display text links ads in this site's sidebar only for $30 in a month.

I) Finally, the most and reliable way, in fact best way to get backlinks to your site is the article review. Article review is the way that you tell someone or some web site that are dedicated for this job to write articles in a person's high rank blogs and in the article post add one backlinks about your site. This is the highest possibility that people will read the blog and will browse the link and in turn visit your blog. So in both ways you are getting benefited. Your page rank will be increased as well as you will get traffic at the same time.

Just for your information if your product/site is related to my blog then for the review you can contact me directly to my email address a_arju@yahoo.co.uk
I take per review $20. But if you write the contents and if the contents are unique I will take $15 per review.

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Different types of Image file formats

You possibly have seen different types of image file formats like .jpg, .bmp, .tiff etc. In this post I will discuss very briefly about different types of image file formats.

Before discussing image file formats it is good to know that there are two image compression algorithm. One is loseless which reduce the image size but does not hurt image quality and another is lossy image compression algorithm which reduce the image size as well as reduce image quality.

Image file formats can be categorized into two. A)Raster formats B)Vector formats.

A)Raster formats: This image file formats store images as bitmaps.
The following image file formats falls into Raster category.

1)JPEG: The name JPEG stands for "Joint Photographic Experts Group" and in most cases the file format is in lossy format.

2)Exif: The Exif stands for Exchangeable image file format. It was coded for exchange image between cameras.

3)Tiff: The TIFF stands for Tagged Image File Format. It is very flexible format as well as need less space than other format.

4)PNG: PNG stands for Portable Network Graphics. It supports true color that is 16 million colors. The size in PNG is greater than JPG format.

5)GIF: GIF stands for Graphics Interchange Format. It can only support 256 colors. But still gif format is widely used because with small amount of colors it can create cartoon style image, logos and it supports animation. GIF formats use loseless compression.

6)BMP: BMP files are for windows only and they are uncompressed. Because of that BMP files are extremely large. If you convert a bmp file of 3M to jpg file then it can become only 100K.

7)PPM, PGM, PBM, PNM image file formats also are an example of raster formats.

B)Vector formats:
Vector image file formats can contain bitmap data as well as it contains 3D graphic file formats.
Example of vector formats are CGM (Computer Graphics Metafile),SVG (Scalable Vector Graphics), ODG (OpenDocument Graphics), EPS (Encapsulated PostScript), PDF (Portable Document Format), SWF (Small Web Format), WMF / EMF (Windows Metafile / Enhanced Metafile), XPS (XML Paper Specification).

For any image/video you can buy camera and take photo yourself. You can also get help any photographer or any multimedia production services as well and in any type of formats. They have variety of devices which can help you. If you are looking for multimedia production services for your website or any type of editing of multimedia you can have a look at various Corporate Video.

Typhoid fever - Symptoms, Diagnosis, Treatment

I am writing this topic because 1 month ago I had typhoid fever and I was not treated well in one of the Bangladesh non-government hospital. I was admitted into hospital after the fever but the doctors in the hospital repeatedly changed my medicine and their treatment was bad in the end. So to get cure myself I took help from a famous rural area's non MBBS doctor and it was great treatment. I am saying this because after I am recovered I did search lots with typhoid fever in google.

In this post I want to share my experience with typhoid symptoms, diagnosis and treatment.

Let's know what causes a man typhoid fever. Typhoid fever is caused by the bacterium Salmonella enterica serovar typhi. This typhi bacteria is then transmitted by the ingestion of food or water contaminated with faeces from an infected person and cause a man typhoid fever.

Symptoms of Typhoid:
- For the first few days a common influenza virus type fever you will feel. And your body temperature also will be between 99 to 101 degree Fahrenheit.

- But after someday you will feel your body temperature goes high and is between 102~104.5°F.

- After taking paracetamol type medicine, within 2 hours you may get excessive sweating.

- gastroenteritis is common of typhoid symptom.

- After 1 week nonbloody diarrhoea is very common. In fact you may need to go to toilet once for each 2 hours.

- In the first week you may have headache. Though I have never had headache but I had headache in this typhoid fever.

- Patient may also face abdominal pain.

- In fact an untreated typhoid fever is divided into four individual stages and each stage lasts approximately one week. In my case it lasted 3 week because I took medicine.

In the first week, if you test your blood then widal test comes negative. Blood cultures test are positive for Salmonella Typhi or Paratyphi. Fever does not rise much in the first week.

In the second week, there is high fever, 103~104°F is common. Diarrhoea occurs in this stage and stool has a characteristic smell. Stool is similar like pea-soup. The spleen and liver are enlarged in this phase. The doctor did X-ray and they told me my spleen is slightly became larger. But I feel pain whenever someone presses my belly. In second week the Widal test is strongly positive with antiO and antiH antibodies. Blood cultures are sometimes still positive at this stage.

In the third week, there may be very serious complication if you don't treat it.

In the fourth week, fever started reducing. If you don't take correct medicine death may occur.

Diagnosis of Typhoid
In the symptoms already stage by stage diagnosis is discussed. You can diagnosis typhoid by testing blood, bone marrow or stool cultures. Based on Widal test you can diagnosis typhoid fever.

Treatment of Typhoid fever
As with me I saw Azithromycin is best at treating typhoid. This may be specially true for Indian Subcontinent. If you are not from Indian subcontinent you can take fluoroquinolone drugs and ceftriaxone. However don't take ciprofloxacin, ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole and streptomycin as a first line treatment. But my hospital doctor gave me ciprofloxacin at first and that's why it took me more day to recover. Later I take Azithromycin with ciprofloxacin.

From internet I also saw medical life today became more easier. You can now control medical treatment wherever you are. For old man/woman if they have a FALL ALERT detector then it alerts emergency personnel that they have fallen and cant even push a button. If you are outside then even with GPS Tracking Bracelet with 2-way speakerphone you can ask for help. It can be used with mobile phone. There is so many Medical Alerts devices exist.

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Friday, June 19, 2009

Different types of web hosting services based on application

If you divide the web hosting service based on it's application then you will get following different types of web hosting service - in which each one is described briefly.

1)File Hosting Service: This type of web hosting server only store files. May be simple text file, zip file, Audio file, video file, .iso file or any types of file but no web pages. User can upload file into the host server via ftp or any web interface. Most of the file hosting service offers free service with some restrictions like file size limit, captcha entry, bandwidth limit, total storage size, file expiration etc. The common example that offers file hosting service are rapidshare.com, megaupload.com.

2)Image Hosting Service: An image hosting server store images inside it and image hosting service offer users to upload images into their server. Image hosting service can offer upload image through ftp access and/or web interface. In both case you can upload multiple images at a time. Image hosting service can offer free or paid service. Free services usually comes with lots of ads in it. The common example of that offers image hosting service are flickr, picasa.

3)Video Hosting Service: As name implies that type of hosting service offers user to upload video, watching video and may be download video. The most common example of video hosting service is youtube.

4)Blog Hosting Service: Blog hosting service offers the support of authoring, editing, and publishing blog posts and comments. People can read your blog and comment on it. It also offers for image management, web syndication, and moderation of posts and comments. The most common example of blog hosting server is blogger.com and I use it to maintain my blog. You can also run your own blog hosting service and there are many free and open source weblog software that offers you to do blog hosting.

5)Social network Hosting Service: This type of hosting service offer you to store your general information, image, video and let you be connected with your friends. The common examples are facebook, myspace etc.

6)Game server hosting: A game server is a remotely or locally run server used by game clients to play multiplayer video games. Various strategic game or action games are played usually through game server. Most cases games are played over the Internet operate via a connection to a game server.

Lastly you can buy your own dedicated web server and decide which type of services you will provide. And if you want to choose many alternatives of web server and identify/compare cost between them you may see various web hosting companies searching through google.

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Thursday, June 18, 2009

Warning: Cannot modify header information -headers already sent

Problem Description
Whenever you run a php file in the browser it shows the following warning message.
Warning: Cannot modify header information - headers already sent by (output started at E:\xampp\htdocs\mock9\pro01.php:86) in E:\xampp\htdocs\mock9\pro01.php on line 168

A variant of above error is after Warning message a function name is appended and then a error message before displaying "headers already sent".
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at E:\xampp\htdocs\mock9\index.php:4) in E:\xampp\htdocs\mock9\index.php on line 9

Cause and Problem of the Problem
This error "headers already sent" indicates that there are spaces, new lines, other garbage words or in fact any words before an opening tag <?php or after the ending tag ?>.

This same error also occur in fact case 1) if you display any output before sending any header information. Like if you display output like,
echo $query;

before sending header information like before line,
header ("location: pro02.php?pid=$pro_id");
then above error will appear.

It is important to note that with the error message
output started at E:\xampp\htdocs\mock9\pro01.php:86) in E:\xampp\htdocs\mock9\pro01.php on line 168
- It mean that the problem is inside E:\xampp\htdocs\mock9\pro01.php
- The line number that cause the problem is 86 not 168.

Similarly by error message,
output started at E:\xampp\htdocs\mock9\index.php:4) in E:\xampp\htdocs\mock9\index.php on line 9
indicates that,
- Victim file is E:\xampp\htdocs\mock9\index.php
- The problem is in line number 4.

Solution of the Problem

Class concepts and usage syntax in php
Control Structures in php
Track error messages on php
Magic constants in php
Datatypes in Php
Operators in php

Wednesday, June 17, 2009

New features in Oracle database administration in 11g

This post will discuss about new features of oracle database 11g administration. Every Oracle database major release comes with new features and step by step some new features are discussed here briefly that comes with Oracle database 11g.

1)Improved Automatic Memory Management:
In 10g in case of automatic memory management we knew that if SGA_TARGET is set then all dynamic SGA components will be automatically managed and if PGA_AGGREGATE_TARGET is set then pga components will be automatically managed. But starting with oracle 11g both pga and sga memory can be managed automatically by setting only MEMORY_TARGET parameter. However you can still assign minimum sizes individually for the SGA and instance PGA.

2)New fault diagnosability infrastructure:
The fault diagnosability infrastructure are for easy diagnosis for any critical problems. After a problem has been occurred it gather necessary information against the problem and then an Incident Packaging Service packages all diagnostic data for a problem into a zip file so that you can transmit that to Oracle Support and thus reduce time to gather information about the problems.

3)Invisible Indexes:
Now in 11g you can make an index as invisible state in stead of dropping it or mark them unusable. It is very effective in order to test performance of a query to see whether removing index will improve the performance. By default an invisible index is ignored by an optimizer but is maintained during DML statements. You can change the initialization parameter to cause the optimizer to use invisible indexes.

4)Virtual Columns:
In tables you can now include virtual columns. In fact the value of a virtual column in a row is derived by evaluating an expression. The expression can include columns from the same table, constants, SQL functions, or even user-defined PL/SQL functions. You can create index and do partition on the virtual columns.

5)Enhanced Security:
In 11g now by default your password is case sensitive. So you can use mixed case password. Though by editing initialization parameter you can make password case-insensitive. More about it is discussed in the topic http://arjudba.blogspot.com/2008/04/password-is-case-sensitive-in-oracle.html

6)Database resident connection pooling:
Database resident connection pooling provides a connection pool in the database server for typical Web application usage scenarios where the application acquires a database connection, works on it for a relatively short duration, and then releases it. Database resident connection pooling significantly reduces database resources needed to support a large number of client connections and thereby boosting the scalability of both middle-tier and database tiers.

7)Tablespace level Encryption:
You can now encrypt a tablespace that contains sensitive data. Tablespace encryption is completely transparent to your application and when you encrypt a tablespace, all tablespace blocks are encrypted also.

8)Invalidation of dependent schema objects are greatly reduced:
Before 11g if we make any changes in the main object then dependent object become invalid. In 11g invalidation of dependent schema objects in response to changes in the objects they depend upon is greatly reduced and thus increasing application availability during maintenance, upgrades, and online table redefinition.

9)Enhanced automated maintenance task infrastructure:
Though in Oracle 10g you had automatic optimizer statistics gathering, Automatic Segment Advisor, and Automatic SQL Tuning Advisor. In 11g you can now exercise finer control over automated maintenance task scheduling.

10)Transparent data encryption enhanced:
Now in 11g using the transparent data encryption feature you can now encrypt SecureFile LOBs.

11)Table compression now supported in OLTP environments:
On compressed tables you can now run DML operations and adding or dropping columns of a compressed tables.

12)Query result cache in sga:
Now query results can be cached in sga memory in the result cache. The database can then use cached results to answer future executions of that query. It is also true for query fragments. As because retrieving results from the result cache is faster than rerunning a query, frequently run queries experience a significant performance improvement when their results are cached.

13)Default automatic undo management mode:
In 10g if you create database manually then the parameter UNDO_MANAGEMENT became MANUAL as by default UNDO_MANAGEMENT is manual in oracle 10g. However if you created database by dbca it makes the parameter AUTO. In 11g by default UNDO_MANAGEMENT is set to AUTO. A null value for the UNDO_MANAGEMENT initialization parameter now defaults to automatic undo management.

14)Enhancements to Oracle Database Resource Manager:

15)Enhancements to Oracle Scheduler:

16)Enhanced online index creation and rebuild:
Before oracle 11g we can do online index creation and rebuild operation but it required a DML-blocking lock at the beginning and at the end of the rebuild for a short period of time. The DML blocking lock can lock other DMLs and thus performance problem can arise while doing online index creation and rebuild operation. In 11g this lock is no longer required, making these online index operations fully transparent.

17)Tables with materialized view logs can now be redefine online:
Prior to 11g online redefinition of a table that have materialized view logs were not possible. But in 11g tables with materialized view logs can now be redefined online. Materialized view logs are now considered one of the dependent objects. So they can be copied to interim table using DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS package procedure. To know more about online redefinition have a look at Make a non-partitioned table into partition table using online redefinition .

18)Facility to make a table read only mode:
Now to avoid any update or insert or delete on a table you don't need to make whole tablespace in read only mode. In 11g with ALTER TABLE statement you can place a single table into read only mode.

19)DDL commands can wait for locks:
Prior to 11g if you have any DML operation running against the table then you can't do DDL commands on the table and instantly ORA-54 message would return as demonstrated in ORA-54 Resource Busy. But in 11g you can now set a single initialization parameter, DDL_LOCK_TIMEOUT, to specify how long a DDL command waits for the exclusive locks that it requires on internal structures before it fails. So we might not need wait for prompting further command to test whether we can run DDL commands. Oracle will check and if no DML operations DDL commands will be performed if it get resource free within DDL_LOCK_TIMEOUT time.

20)Enhancements to initialization parameter management:
There are several enhancement in the initialization parameters.

Upon startup, values of initialization parameters are written to the alert log in
such a way as to make it easy to copy and paste them to create a new PFILE.

The name and path of the PFILE or SPFILE used to start the instance is written
to the alert log so we need not to search which one is used to startup database.

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Move your homes from one place to another

Moving from one house to another is a difficult job and sometimes fun for adults, but
it can be especially troubling for children. Though if parents deal with their children’s concerns and needs thoughtfully, much of that distress and discomfort can be avoided.

Children see moves differently than their parents do, and they benefit much less from the change in their comfortable routines- or so it seems at the time. Most often, a change in houses or communities heralds an important step forward for the adult members of the family. Normally a family moves because his father or mother got a great new job, or promotion in reward for years of hard work. It is not uncommon that someone is moving their houses to rural area in order reduce their house rent.

People may move because financial success has allowed the purchase a bigger and nicer
house in a more costly neighbourhood. They move because they can finally afford
private bedrooms for each child and perhaps a pool in the back yard or it may be vice-versa.

My friend was supposed to move from New York to Alexa and he told me it is the most cumbersome things in this living life. I then search through net and researching it about any site that offer good services and take all responsibility themselves.

I got several sites in fact many companies that do this pack and shift type jobs.

Out of them I can mention moveme.com which offer several alternatives you can choose.

You can get both a man and a van from them.

And their service that I like is they offer international moving too.

At last these types of companies make life easier in case of moving. Though you can move yourself but there is more hassle than any company offer.

The documents you might be interested
http://arjudba.blogspot.com/2009/04/why-i-dont-like-to-use-yahoo-service.html
http://arjudba.blogspot.com/2008/08/some-tips-of-mozilla-firefox.html
http://arjudba.blogspot.com/2008/11/list-of-country-calling-codes-in-world.html
http://arjudba.blogspot.com/2009/02/how-to-add-google-search-box-to-your.html

Tuesday, June 16, 2009

What is web hosting service?

Well, let me start with a simple example. You stay in a house, you/your family either buy it's space or you rent a house and you pay per month for it's space. Similarly in internet, you see the contents - contents may be text, image, video or any graphics and these contents need space to reside or in order word there must be some hosting company that is responsible to provide space for these contents.

A web hosting service is a type of internet hosting service that allows you to provide their own website accessible through internet so that they can rent their space for you. Then you can browse their site and take decision whether you will use their hosting service or in other word whether you will host your contents to them. A web hosting company can provide you space on a server they own or lease for use by their clients as well as they provide Internet connectivity with their server so that your hosted contents can be accessible through worldwide.

Based on the services they offer web hosting services can be divided through various ways.

1)Free web hosting service: In most cases they offer limited service and some of the time web hosting server wants a advertisement within your web page.

2)Shared web hosting service: Many websites share a single web hosting server.

3)Reseller web hosting: Allows client to host their server themselves. And their services vary based on reseller.

4)Virtual Dedicated Server: Resources of one server is allocated to many websites and each website owner may be responsible to manage their contents.

5)Dedicated hosting service: The user is not own the server but web hosting site dedicate a server for the user and user have the root access of the server.

6)Managed hosting service: The user does not have full control but have access to ftp their contents. The web site provider site is responsible to ensure the quality of service.

7)Colocation web hosting service: Most powerful and expensive. The hosting company provides physical space for the server and take care of the server. But the user owns the server machine and have full control of the server machine.

8)Cloud hosting: It removes single point of failure and also cost depends on the user what services they use.

9)Clustered hosting: Multiple web hosting server hosts the same content for better resource utilization. As contents reside in multiple server so Clustered Servers are the best solution for high-availability hosting, or creating a scalable web hosting solution.

10)Grid hosting: An enhancement of clustered hosting. In this case each cluster is composed on multiple nodes.

11)Home server: Privately in a home you can establish a server and can use that.

Now it is a question where I will get these hosting company in order to host my website content. In fact there are so many companies that offer web hosting service. Some popular site is godaddy.com. In fact you can so many companies that offer verious types of web hosting service. There is too many sites which are the guide for Affordable web hosting packages available online. This hosting guide has more than 200 approved web hosts with over 400 cheap web hosting packages listed.

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