Thursday, November 12, 2009

MySQL Server Replication (5.0.84)

Hi all,

    Today I tried setting-up MySQL server replication for 5.0.84. Must say its kind of really easy to setup a simple replication between 2 MySQL server instances. Putting down some key points to be followed.

  Note:  Make sure that no processes are updating master server while we perform underlying operations.

Steps provided in this blog are applicable to both 32 bit and 64 bit version of MySQL.

  Setup a replication of a Database "nba_hiber_test" on Master server on other Slave Server with same DB name over there.


If you are making Master slave for a fresh DB, where there is nothing on the Master, just create DBs on both Master and Slave DB and directly go to Step 3.

#1. Take Backup Dump of Master DB :
   If Source (Master) database is already there on some DB which is still going to act as Master server in replication environment, please export Master database using command at shell prompt as below:
    mysqldump --add-drop-table  -h  -u zuber -p nba_hiber_test | bzip2 -c > nba_hiber_test12Nov09_with_data.sql.bz2

      Here was the machine on which my existing Master database is located, and that DB's name is "nba_hiber_test". This will create a compressed bzip2 file of SQL file and store it at the present working directory.

 #2. Import DB on the slave DB:
     Transfer "nba_hiber_test12Nov09_with_data.sql.bz2" to the slave machine.
     We need to put the exact copy of the Master database on the slave server before we can enable replication. To do that, import the database on the slave machine from "nba_hiber_test12Nov09_with_data.sql.bz2"

        a. Decompress "nba_hiber_test12Nov09_with_data.sql.bz2" :
                bzip2 -d nba_hiber_test12Nov09_with_data.sql.bz2

        b. Login to the MySQL on slave box and Create DB with same name as on the Master server (here "nba_hiber_test"):

                create database nba_hiber_test;

         c. Assuming you started MySQL client from at the same location where u ran command 2.a, run that SQL fil against "nba_hiber_test" on slave box:
               # start using target slave DB
                    use nba_hiber_test;

              # Run SQLs in "nba_hiber_test12Nov09_with_data.sql"
                    source nba_hiber_test12Nov09_with_data.sql;

        This import may take time depending upon the size of  the database and the hardware on which you are running MySQL. Use that time to go thru this whole document rather than waiting and looking curiously on the black screen ;)

  #3. What we did? :
         At this point, we have identical copy of Master and Slave dbs on bothe machines.

  #4. Configure Master server to generate bin logs that can be used pass replication info:
   This will be needed only if you are starting using this server as Master in a replication environment fpr the first time
   To confirm if server is acting as Master or not fir "SHOW MASTER STATUS;" command on mysql prompt. If no records returns, means you have to configure it for master.
     Add following lines inside [mysqld] of "my.cnf" file.
    # folder path whre mysql will store its log-bin files

    # databases for which the replication info (log-bins) to be generated

    #Change server id to some unique number in the range of 0 to 2^32 - 1
    server-id       = 1 

     Most of the time "my.cnf" is located in "/etc" folder. You will need root access to change the file and restart the server.

  #5. Restart Master DB:
        /etc/init.d/mysqld restart

  #6. Confirm that bin logs are getting created:
        Login to Master DB and fire:

    Assume its running fine if you see something like:

    mysql> show master status;
        | File                | Position | Binlog_Do_DB | Binlog_Ignore_DB |
        | bin-log.000001      |       98 |              |                  |
        1 row in set (0.00 sec)
  #7. Find out the log position on which Master server points to right now :
    KEEP A NOTE OF THIS HADY to provide it to slave later:


  #8. Create replication user on the Master server to be used by slves to connect to do replication:

    CREATE USER 'repl'@'%' IDENTIFIED BY 'passwd';

  #9. Configure Slave server to give details of what all databases on this server are to be popullated with replication.
      Add following lines inside [mysqld] of "my.cnf" file.

          #Change server id to some unique number in the range of 0 to 2^32 - 1
          server-id       = 2 

  #10. Restart Slave DB:
        /etc/init.d/mysqld restart

  #11. Stop any existing Slave threads on Slave Server:

        STOP SLAVE

  #12. Setup the Master info on Slave DB:
         Note that we pass same values of "file" and "Position" in this command as found on step 7.
    MASTER_HOST = '',
    MASTER_USER = 'repl',
    MASTER_PASSWORD = 'passwd',
    MASTER_LOG_FILE = 'bin-log.000001',
    MASTER_LOG_POS = 98;

  #13. Chkeck the Slave thread status to see if is able to connect to the Master DB or not:


    This commend should give you something like this as result:

        *************************** 1. row ***************************
             Slave_IO_State: Waiting for master to send event
            Master_User: repl
            Master_Port: 3306
              Connect_Retry: 10
            Master_Log_File: bin-log.000003
        Read_Master_Log_Pos: 41435
             Relay_Log_File: mysqld-relay-bin.000006
              Relay_Log_Pos: 41570
          Relay_Master_Log_File: bin-log.000003
           Slave_IO_Running: Yes
          Slave_SQL_Running: Yes
            Replicate_Do_DB: nba_hiber_test
             Last_Errno: 0
               Skip_Counter: 0
        Exec_Master_Log_Pos: 41435
            Relay_Log_Space: 41570
            Until_Condition: None
              Until_Log_Pos: 0
         Master_SSL_Allowed: No
          Seconds_Behind_Master: 0
    1 row in set (0.00 sec)

  #14. Test:
        Now try creating some records in the Master table, and check its getting reflected in the Slave server in some interval.

  Wish you Happy Replication

Sunday, September 13, 2009

Hibernate: Easy to JUST Use...But HARD to use in Right way

Recently started working on migration of one of our application to port on Hibernate. To be frank, I dont know much of hibernate. At the same time, from bottom of heart, am not all that big fan of Hibernate as well !!
But yes, taking this as an opportunity to learn hibernate and looking for some concrete reasons to LOVE or HATE it :p
So started looking around for some good online articles to get booted up. At first glance simple ORM looked so straight forward that I felt like in heaven to be a developer using Hibernate. But soon, realized a devil a residing in the heaven. That is why the title of the post is "Hibernate: Easy to JUST Use...But HARD to use in Right way" !!
Yes, this is what I have felt so far, I may change my opinion later :p
One of the main reason why I felt so is the way we use "OneToMany" association with "inverse" attribute and "cascade" attribute.
I definitely want to thank all smart poeple who put their articles to help newbie like me to understand Hibernate. Giving some links below in the order of my likings towards the explanation :

Friday, August 14, 2009

Independence "In-Deep-Essence" to me

62 Years of so-called "Independence" !!
Yes, this is what I feel when I see people feeling happy that they got their nation from Britishers, who looted us just like mankind loots honeybees.
But are we able to digest this Independence??
I always ask this Question to me.....What this Independence really means to me ??

> Does it just mean to throw Ruling Britishers out of the country and let our own corrupted people to loot us?
> Does it mean to break our own country, friendship and create India , Pakistan, Bangladesh, Kashmir, POK ?
> Does it mean to break Indians into caste (SC / ST / NT / OBC ), religion, and state ?
> Does it mean to remember and give respect to flag, national anthem for a day and then throw in dustbin on next day?

If answer is yes, then I am sorry to say, but I would have been happy to see Britishers only to rule me and my nation !! Yes, because in that case atleast we, all Indians would have been together forgetting caste, religion and states. We (Post Independence) as a generation got Independence for free, may be that is why we dont value it.

We say that we are one of biggest democracy in place. But what is use of such democracy where we are only in power just during election time. We elect our representative. Then for next five years they will suck us with all their power. Nothing happens as common man wants. Still we call it democracy.

I thought Independent country has aware civilians. And civilians are as aware as media over there is. But thankfully our media is too busy capturing child in hole, sexy actresses in movies, thug baba's bahvishyawanis and cricketer's favorite food.

We can't even blame politicians only for all this. We as individuals, care for personal benifit more than that of country and more broadly for every living being.
> Why we want to diffenetiate poeple based on caste during any procedure?
> Why we want reservation?
> Why we want to break indians based on their native state?
Politicians shows us dreams, breaks it everyrime, and we still support them everytime.

To me, we have just got Independence from one perspective. There are still having challanges from many enemies of ours whom we are still slaves to !!! These are bigger than and much powerful than what britishers were. To my small mind, following are those, but there might be many others....

1. Corruption
2. Racism
3. High valie of Money infront of value of any living being's life
4. Selfish outlook / politics

Dont forget, "Together we stand, alone we fall". To f*ck all above enemies, we have to come together. We have to play our role. We may differ in our way of fighting, but our goal will be same and noble. Are you fighting for your self ? For your family ? For your country ? For every one who breaths ?

Monday, July 13, 2009

Democracy OR Daemōn-Cursing

Yes I am frustrated. Yes I am impatient. Yes I am confused about so called golden word "Democracy", please help me if you think you understand it But before all let me tell you that I don't support any political party :P
Here are few questions that I have:
  1. We have right to vote, but are we getting right candidates to vote to?
  2. We have right to speak, but is government having time to listen to it?
  3. We call democracy in country, but do we feel people ruling OR (Fair) rules in place for people of country ?
  4. Do we need statue of a (Shit) politician at cost of crores of rupees that we pay as tax?
  5. Who is Common Man (Aam Adami) according to out great politicians ?
Actually above general questions are touching many small questions that I have in my small and dumb mind.

What I am frustrated about ?? :
  1. Do we need statue of a (Shit) politician at cost of crores of rupees that we pay as tax?
  2. Do we want to give 100% tax benifits to donations given to political parties ( by businessmen)
  3. We have concerns about getting our black money out of tax heaven country, but can't we focus on atleast making sure that all black (Real estate for example) transactions that occuring in the country itself?
  4. Do we want to give more tax benefits to people who are already earning over 10s of lacs per annum or to a common man ?
  5. We dont have 24 Hrs. of electricity even in 60 Km surroundings of Capital hub (Mumbai) of India, and we want to make it Shanghai (LOL) !!
If we keep on listing these I think google server's diskspace will also be less for us. But instead of focusing on issue I feel we (yes, I meant WE ALL) should start focusing on the solutions.

  • Small things CAN bring BIG Differences : Yes, I am a true believer of this statement. And I always tried (I think, I always Had ever since I think I felt being responsible) to be practical with it. But question is, "What I can do alone ???" hmm... good Q, but here are something that we can always do, and we dont have to depend on others atleast for these things :
==> Bad Power and Fuel situation is there, but can't we make our power requirement bit less?? Howw?? Here they are:
= Can we keep our tubelights off during the day time whenever possible ?
= Can we switch off all the electrical and electornic items aound us which will be idle after we leave our office premises? Even standby mode eat power, no matter how low, still there is still power being wasted for no good reason. Do we keep our monitors on when we leave our home? No,why? Because we pay the light bill...then why we forget to switch it off when we leave office ??
= Can we take a walk/bicycle ride whenever possible instead of bike or car?
= Can we use email instead of paper printout. And if at-all print is necessary, can't we mandate to make print papers to be used both sides ?
In short If we have got freedom, we gotta use it with responsibility
  • Do It your self b4 asking some1 else to : We always crib about politicians (Government) not doing their job blah blah... I would say, we DON'T have right say it. Whyyy ??
==> As a responsible person of country its our responsibility to pay (complete and honest) tax. But are we doing so ?? We are asking others to do their job honestly, but we want to exempt our self from it. And when asked, we always have reason "As they are not doing their job, why should I ? ".

But what we are forgetting is that we are putting thing in a infinite loop here. We can start paying taxes and then screw and force govt. to do their task. Govt. is made up of poeple like you and me. If we all are doing our job with responsibility, then we can definitely pluck few remaining assholes out of the business to get the healthy environment !!

Now I feel, I haven't listed any of the solutions which I feel needs a rocket science to implement.

Yes, I am positive about this. Yes I am waiting but acting for this. And Yes if I can do it, everyone else can !!