How Google Mesa works ( short summary )

Mesa is a highly scalable analytic data warehousing system that stores critical measurement data related to Google's Internet advertising business.

Mesa leverages common Google infrastructure and services, such as Colossus (Google’s next-generation distributed file system)  BigTable, and MapReduce. To achieve storage scalability and availability

http://research.google.com/pubs/pub42851.html

Characteristics and Goals

• Data is horizontally partitioned and replicated.
• To achieve consistent and repeatable queries during updates,the underlying data is multi-versioned.
• To achieve update scalability, data updates are batched, assigned a new version number, and periodically (e.g., every few minutes) incorporated into Mesa.
• To achieve update consistency across multiple data centers, Mesa uses a distributed synchronization
• protocol based on Paxos

How it is different from existing Google tools

• Megastore, Spanner, and F1 all three are intended for online transaction processing they do provide strong consistency across geo-replicated data but they do not support the peak update throughput needed by clients of Mesa.
• Mesa does leverage BigTable and the Paxos technology underlying Spanner for metadata storage and maintenance.

What to learn

Schema changes for a large number of tables can be performed dynamically and efficiently without affecting correctness or performance of existing applications

How it works

• It uses associative and commutative functions based  aggregations in tables
• While new version-ed information is being calculated old version is used to server the applications
• When all calculations are over the version is incremented and users issue queries against new version
• Upstream systems generate updated data in batches
• The committer assigns each update batch a new version number and publishes all metadata associated with the update (e.g., the locations of the files containing the update data) to the versions database, a globally replicated and consistent data store build on top of the Paxos consensus algorithm.

Schema changes handling

The method Mesa uses to perform online schema changes is to 

(i) make a separate copy of the table with data stored in the new schema version at a fixed update version, (ii) replay any updates to the table generated in the meantime until the new schema version is current, and 

(iii) switch the schema version used for new queries to the new schema version as an atomic controller BigTable metadata operation. 

Older queries may continue to run against the old schema version for some amount of time before the old

schema version is dropped to reclaim space.

Get direct link of google result

At times you want direct link of Google search results.

Google now try to add redirect information for lots of tracking it does behind the scene. I cliicked this , i went here and etc.

If you want direct link for copy paste purpose then you might want to try this addon

https://addons.mozilla.org/en-US/firefox/addon/google-search-link-fix/

Install it

Then you can just copy the link via , Right click > Copy Link location

The statergy behind Google reader phase out

If i see Google statergy to bring people who are using Google reader to G+ , then it makes sense for them. For example we all spend lots of time with facebook , if facebook have inbuit rss reader like Google reader people will inturn spend more time inside fb and also share the posts they read with friends network. Although there are apps which do this , but many dont explore fb apps.

Okay coming back to Google decision on Reader phasing out. If whole statergy is to make G+ as default place for people to work on in Google ecosystem then soon reader should be embedded here. So that i can share with my circles what i am reading and Google+ also becomes happy with increasing traffic.  The major issue with G+ is lack of colors :) which Google did not understand till now. People dont like dull whites with lots of hidden blurred buttons to make them think where to click :) , Are you doing any usability study for G+ ? World outside Google is not Geek they want colorful stuff.  #googlereader

Google are you listening ? :)

How to add Google Analytics in Blogger

Other day i was looking for some gadget built in to use Google analytics with Blogger. Then i found that its not there and i have to add it directly into the code.

Here are the steps which you have to follow to use Google Analytics in Blogger.

1. Go to Blogger Dashboard and for the blog in which you want to add Google Analytics click Design
2. Click Edit HTML ( Present on top horizontal navigation)
3. Search for </body> tag in the code and just above it add the Google analytics code which you got from Google analytics website.

Save it and you are done.