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Subject: read on multiple SS tables
From: Ramesh Natarajan <ramesh25@gmail.com>
To: user@cassandra.apache.org
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Lets assume I perform frequent insert & update on a column family..
Over a period of time multiple sstables will have this row/column
data.
I have 2 questions about how reads work in cassandra w.r.t. multiple SS tables.

-If you perform a query for a specific row key and a column name, does
it read the most recent SSTable first and if it finds a hit, does it
stop there or does it need to read through all the SStables (to find
most recent one) regardless of whether if found a hit on the most
recent SSTable or not?

-  If I perform a slice query on a column range does cassandra iterate
all the SS tables?

We have an option to  create

1st option:

Key1 |  COL1 | COL2 | COL3 .....  <multiple columns >

We need to perform a slice query to get  COL1-COL3 using key1.

2nd option:

Key1 |  <COL as one column and have application place values of
COL1-COLN in this one column>

This key would be updated several times where the app would manage
adding multiple values to the one column key. Our max col value size
will be less than 64mb. When you need to search for a value, we would
read the one column and the application would manage looking up the
appropriate value in the list of values.

So I am wondering which option would be most efficient from read point of view.

thanks
Ramesh