Wednesday, July 10, 2013

Teradata Interview Questions - 1

  1. What is a Primary Index ?
  2. What is a secondary Index ?
  3. What is the need of a secondary Index ?
  4. What is table skewness / skew factor?
  5. what is 
    1. currentperm
    2. maxperm
    3. peakperm
  6. What is MPP ? how does teradata leverage that ?
  7. What is Teradata Virtual Storage ?
  8. what types of data compression does Teradata support ?
  9. What is a Clique in Teradata ?
  10. What is a hot standby node in Teradata ?

Monday, March 25, 2013

Laptop Hard disk crashed..

The laptop Hard disk crashed, and in the process, I lost quite a bit of photographs and videos of the newborn.

It was an IT disaster, that I have encountered for the first time ever, and has prompted me to think more seriously about putting my content (photographs and video etc) on cloud (amazon S3)..

In the meantime, the baby is going strong, and has been showing signs of responding to human interaction. For Example, she has started responding to "hi baby" and stuff like that, sometimes we caught her smiling as well...

Here are some photos from the days I got my new hard disk up and running...

Sunday, March 24, 2013

Cord blood Banking for the second one...

Well, Technology progresses fast, and expectedly, the cord blood banking technology, and the facilities and benefits linked to that, in addition to the possibilities have improved a lot since our first ones'.  At that time also, we chose the best available option, and went ahead with Cryobanks for banking his cord blood

This time around, after doing some more research, we chose to go with a different vendor, life cell international. They are also a renowned organization, involved with the cord blood banking business for quite some time. 

One of the primary reasons for choosing Lifecell was that we wanted to chose two different organizations handling the banking of our two kids. if something does go wrong with one of them, at least the other one would still have the blood available.

Also, there is a new technology where they grow and do tissue banking for the baby, which can be utilized for the baby and in some cases, siblings, parents etc.  We have opted for that too.

Tuesday, March 19, 2013

Day 3

And now he's got a sister...

After much discussion and debate in the household, we finally decided to have a second child. And on 16th March 2013, Ira has come into our world, our own incarnation of godess Saraswati and Lakshmi...

With this life changing event, our own kaka, has become a big brother now.... and we have a sister/daughter female in our family after a generation...

Krishna on his part is very excited, and sometimes over excited too... its hard to contain him, and get him not to touch the baby...

to read more about the baby girl, pls feel free to go to this blog...

Day 4.. and the arrival at home...

Its getting lighter (she has lost about 240 gms) and cosier...especially with the upcoming homecoming...

After the maternity package days were over, it was time to head home, bring the lakshmi to her home...well, the current home that is.  The process was smooth, and the hospital had decorated our car with pink ribbons and pink balloons, in tune with the colour of the female...

The journey home was painstaking since I was trying to be extra cautious with the standard issue indian road :) However good roads you get, you cant avoid potholes and uneven breakers on Indian roads...

Due to the decoration, the car was a point of everybody's attention on the road, basically a head-turner...felt nice :)

Once we reached home, it was really really great... someone has said it right, home is home afterall, nothing in the world quite like it....

Monday, March 18, 2013

Day 3 ...

Day 3 started nicely, no night crying, all slept well.. and woke up rested...

Since it was past 36 hours of birth, there were a few tests due today, and the first order of the day was a blood extraction process, for determining jaundice affliction and other biochemical tests on blood.  Though it was painful to see blood going out of such a tiny body, it was nice to see the excellent way the process was performed. Basically, the whole thing finished in under couple of minutes.. Given the expertise of the nurse attending the child. Good job.

After that, it was the turn of her bath.  I had missed her first bath yesterday, but I wasnt going to miss this one.. So I tagged along, and was again stumped by the efficient way the nurse was performing the bathing.. simply excellent and clean..

Couple of hours later, the blood test reports came out, announcing absense of jaundice.. and the identification of blood group. Nice speed on the part of pathology lab and the staff involved.

Then the "complimentory" photo shoot lady came in and tried to use flash on her while shooting her pics.  I protested, and ensued a bit of a argument/discussion on how to achieve the same effect without flashing baby\s eyes with the blitz of a camera flash...  Eventually, we didnt get the photo shoot done, since the photographer wasnt ready/able to shoot anything without using a flash...  Instead, I clicked plenty of shots of the baby (all without flash, bit higher ISO, and a lower f number setting normally does the trick, ofcourse ambient light helps).

Tomorrow there shall be some other tests, and we'd be taking the baby home for the first time...

Sunday, March 17, 2013

Day 3

Day 2 shot...

Another one from day 2

Day 2 photos

Day 2

Well, the enjoyment of arrival of the baby has been subdued a bit due to the fact that I have been suffering with fever and cough since the afternoon before (15th afternoon).  Couldnt do a lot of things that I would have normally taken up...  I havent even held her in arms for a full 5 minutes, for the fear of infecting her with my viral..

There is a constant fear that i might be putting the baby and mom to the risk of infecting with something from me.  as a result, I am constantly living with a mask on my mouth, to control the spread of the germs.. if any...

The progression of the baby in day 2 has been bumpy... with her not sleeping over the night... for unknown reasons that neither the attending nurse nor the mother could understand... finally she slept at around 5 am....

And, while i had gone out to get examined myself (for the fever), they took the baby for bath, and I missed out on recording her first ever bath... I wish I had that on some media...

Saturday, March 16, 2013

the arrival....

Here goes the very first image of the new born...

It was in the morning hours of 16th March 2013, that godess lakshmi has chosen to bless us... at Cloud Nine hospital in Jayanagar, Bangalore.

Friday, January 11, 2013

Teradata TPump vs MultiLoad

Was doing some research around Teradata's load utilities and found some useful info on Teradata forums 

* Loads data to TeraData from a Mainframe or flat file
* Multiple tables can be loaded in the same MultiLoad.
* Up to 20 INSERTS, UPDATES, or DELETES on upt o 5 tables.
* UPSERT is supported
* There can be NO - Unique Secondary Indexes (USI), Triggers, Referential Integrity or Join Indexes.
* Duplicate rows are allowed
* Each Import task can do multiple INSERT, UPDATE and DELETE functions.
* Some Secondary Indexes (NUSI) and RI are allowed
* Locks at the table level
* Block Level transferring of Data.


* Loads data to TeraData from Mainframe or flat file
* Tables are usually populated.
* Can have Secondary Indexes and RI on tables.
* Does not support MULTI-SET tables.
* Locks at the row hash level
* It uses time based checkpoints not count based.If you are using an OLTP the TPUMPs trickle or continuous loads to populated tables. It acts like a water faucet (tap), that is it can be turned up and load millions of rows or at peak periods tuned down to trickle ffed into the tables.Generally MultiLoad performs better for large bulk loads because of the 64k block loading of data and TPump works better on Low volume changes.

General Writeup 
Multiload performs better in almost all cases.

The only time TPump's performance approaches Multiload is when you are updating a very small percentage of the rows. Tpump could probably beat Multiload if you had a very small number of rows in that Multiload has to log on to one session per AMP, whereas Tpump sessions can be controlled. So, with a very few number of rows, the overhead of Multiload may make it slower than TPump.

Multiload performs better because it sends the data from the host to the DBMS more efficiently (in block mode; with no embedded commands).  Tpump sends the data as part of a statement (exec macro statement). Tpump allows you to pack statements together to gain more efficiency, but it's still doesn't send the data as efficiently as Multiload.

The second reason that Multiload is faster is that it then applies the updates in block mode. So, if you have multiple updates destined for the same data block, they will get applied with one physical write of the data block. Tpump will need to write the data block once for each update.

The advantage that Tpump has over Multiload is that it locks only the rows (actually row hashes) that it's updating whereas Multiload locks the entire table for write while it's updating the data.  Because of this, you can run multiple Tpumps against the same table at the same time, whereas you can only run one Multiload against a table at a time.

Since Multiload takes a write lock on the table it's updating during it's APPLY phase (the phase where it actually updates the table), you can only access the table with an access lock (i.e. dirty read). With Tpump, you could access individual rows with a regular read lock.  If you tried to do a query that required a read lock on the table during a Tpump, the read lock would end up blocking the Tpump updates until the query finished, so it's still not a great idea to try to run queries requiring a read lock on the table during a Tpump.

Another advantage that Tpump has over Multiload is that there is no Tpump code within the DBMS, so new features are automatically enabled with Tpump, whereas there are a number of features that you can't use with Multiload (USI's, referential integrity, join indices, etc.).

In summary, 

Multiload is better for bulk updating especially if done in traditional batch mode.
Tpump is usually better for continuous updating of a table.

Thursday, January 3, 2013

Finding Informatica domain name

Recently I came across a situation where the customer people had provided us with informatica server hostname, but not the domain name, nor the port for domain.

In such a case, we lost quite some time figuring out how to go through the domain configuration. That's when I started thinking about the alternates for finding the domain name information from the system (assuming different access levels)

If the repository database access is available, i.e. you can access the informatica repository database, you can use the following query to get the domain name out.

select pos_name

 This sql will need to be run in the schema where the domain repository has been created.

On another approach, if the database access is not there, and the informatica server access is available, another file, domains.infa in the $PM_HOME equivalent directory will be able to provide information on domain name/port etc..

About the port

Though the installations process allows customization of the ports for domain, many installations keep the default as is.  In any case, a simple telnet to the host on the suspicious port will confirm whether the port is open or not.

In my example situation, it turned out to be the default 6005.