Today while exporting I came to know that Oracle XE does not support Bitmap Indexes.

Then to test it out, I login into Oracle XE’s SQL*Plus console and tried to run a create bitmap index DDL sql and result was still negative as follows.
 
So I was convince that it does not support Bit-mapped Indexes..

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Just putting into words what I understand about how Oracle database handles the reading and writing of data.
Did some brain storming in a hope that it will be useful to somebody.
Reading in Oracle is completely handled by Server processes.
All instruction (reading or writing) from client’s processes first goes to server process.
Reading the Data

The server process first checks the buffer cache for the presence of data.
If not found then only copy the data from datafile to buffer cache.
Then send the data to the client.

DML operations
INSERT
A space is found in the block in the buffer cache and data is inserted into […]

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Just trying to brush up few basic concept!
What happens when Oracle processes an SQL Statement?

Step 1: Oracle Create a Cursor
For every SQL, first a cursor is created (cursor creation can occur implicitly, or explicitly by declaring a cursor).
Step 2: Oracle Parse SQL Statement
A SQL statement is parsed only if an identical SQL statement does not exist in the library cache (shared pool-System Global Area). In this case, a new shared SQL area is allocated and the statement is parsed (hard parse), otherwise existing stored information in library cache is used (soft parse).
Hard Parsing is the process of

  Translating a SQL […]

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