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From Hannu Kröger <hkro...@gmail.com>
Subject Row cache functionality - Some confusion
Date Sun, 04 Mar 2018 18:45:43 GMT
Hello,

I am trying to verify and understand fully the functionality of row cache in Cassandra.

I have been using mainly two different sources for information:
https://github.com/apache/cassandra/blob/0db88242c66d3a7193a9ad836f9a515b3ac7f9fa/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java#L476
<https://github.com/apache/cassandra/blob/0db88242c66d3a7193a9ad836f9a515b3ac7f9fa/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java#L476>
AND
http://cassandra.apache.org/doc/latest/cql/ddl.html#caching-options <http://cassandra.apache.org/doc/latest/cql/ddl.html#caching-options>

and based on what I read documentation is not correct. 

Documentation says like this:
“rows_per_partition: The amount of rows to cache per partition (“row cache”). If an
integer n is specified, the first n queried rows of a partition will be cached. Other possible
options are ALL, to cache all rows of a queried partition, or NONE to disable row caching.”

The problematic part is "the first n queried rows of a partition will be cached”. Shouldn’t
it be that the first N rows in a partition will be cached? Not first N that are queried?

If this is the case, I’m more than happy to create a ticket (and maybe even create a patch)
for the doc update.

BR,
Hannu


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