As with any database management system, proper utilization of caches will improve the query performance in HBase. If someone is looking to optimize caching, it is good to understand the HBase data structures since optimization will vary with each use case. The following is a simplistic view of HBase read write path of HBase and the participating components.

HBase has two in-memory data structures (memstore, blockcache) and two on disk data structures (WAL, HFile). During data write, HBase writes data into WAL (Write Ahead Log) on disk and also to memstore in memory. When a memstore utilization threshold is reached data is flushed into HFiles on disk.

Once you start populating data to Graphite database, users can see data on Graphite UI and create custom graphs to see the data in realtime. When graphs are created users want to save the graphs for future use and probably want to create a dashboard with all the graphs created. One simple (but non user friendly) way to accomplish this is to save the URLs of the graphs created and users can use it to bring up the graphs when they need them.

If you have been working on Chef you may already know that attributes and resources in recipes defined in a community cookbook can be modified. But there can be a need to allow users of community cookbook to be able to change the execution flow of recipes in the community cookbook. We will go over an approach using an example.

For anyone familiar with Object Oriented programming this gives a quick run down on the OO aspects of Python language.

A class can be created using the class keyword.

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>>> class Shape(object):
...     """This documents the details about the class Shape"""
...
>>> Shape.__doc__
'This documents the details about the class Shape'

Once we understand the common social norms of interacting with others, it is a matter of knowing how to express it in the particular language to the person we are interacting with. Similarly once we understand the fundamentals of computer programming, it is a matter of knowing the syntax of a particular language to express what needs to be accomplished. The following details the basic syntax of the Python language which will help get started with it and be able to build solutions for most of the programming tasks. The assumption is that the reader is familiar with fundamentals of programming and have been programming is another language.