Google Facebook Twitter Growth

This is buzz all around the net, that Google+ grown faster than Twitter and Facebook. Yeah it seems looking at the graphs and the overwhelming response of the users. It seems that Google+ reached 10 million users in just 16 days. Wow!! but how many are new users to Google, since many users are already associated with Google in some or the other way. Whenever Google introduces any new system, most of these users joined these systems. When Buzz is launched, then also number of Buzz users increased so rapidly. But with Facebook and Twitter, the scenario is bit different, they entered into the internet market and started attracting customers due to theri features. Now, most of the users are already get used to with social networking sites, hope Google+ with groups feature can take the advantage of all.

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Hash Natural Join

To perform hash join, Oracle follows these steps: 1. Oracle chooses the smallest of two tables as the hash table (otherwise called as driving table). Oracle built the hash table in RAM after applying the hash function on the joining column(s) of the driving table. 2. Oracle chooses the other [big] table as the probe table (otherwise called as driven table or probing table). It traverse through all the records of this probe table, applies the same hash function on the joining column(s) [column(s) used to join these two tables] and will hit the corresponding entry in the hash table. 3. Oracle returns the output if a record from driving table is already present in the same hash key, else no record will be returned. It may look like Nested loop join & Hash join have the same architecture since both these have the concept of driving & driven tables but they have entirely different design if you closely look a...

Nested Loop Natural Join

When the optimizer tries to finalize the execution plan of a query, it considers a lot of items. It must take the interrelated decisions based on those items. Most important of those items are, Ø Access path Ø Join Order Ø Join Operation Access path tells how the required data is going to be retrieved from a table. So, this tells nothing but which index scan is imposed on that table like index range, index skip scan and so on. Join Order means, to execute a query that joins more than two tables, Oracle joins two of the tables, and then joins the resulting row source to the next table. This process is continued until all tables are joined into the result. It means oracle can join only two tables at most in a time though more than two tables are referred in a query. Oracle always tries to join the small tables first and then joins with the large tables. The reason behind is, it always tries to lower the number of resultant records formed while in the process of jo...

External Table

External Table is the another type of table which is supported by Oracle apart from IOT and Cluster table. External tables allow Oracle to query data that is stored outside the database in flat files. The ORACLE_LOADER (an in-built driver provided by Oracle itself) can be used to access any data stored in any format that can be loaded by invoking SQL*Loader (an in-built utility provided by Oracle itself to load the data from the flat file into the data table). External tables enable us to read flat-files (stored on the O/S) using SQL. They have been introduced in Oracle 9i as an alternative to SQL*Loader. External tables are essentially stored SQL*Loader control files, but because they are defined as tables, we can access our flat-file data using all available read-only SQL and PL/SQL operations. We can also read flat-files in parallel and join files to other files or tables, views and so on. In this example, the data file (emp.txt) is placed in the location, “C:\test”. Then you ...

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