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From Mark Greene <green...@gmail.com>
Subject Re: Why are writes faster than reads?
Date Tue, 25 May 2010 11:04:08 GMT
I'm fairly certain the write path hits the commit log first, then the
memtable.

2010/5/25 Peter Schüller <scode@spotify.com>

> > I have seen several off-hand mentions that writes are inherently faster
> than
> > reads. Why is this so?
>
> I believe the primary factor people are referring to is that writes
> are faster than reads in terms of disk I/O because writes are
> inherently sequential. Writes initially only happen in-memory plus in
> a (sequentially written) commit log; when flushed out to an sstable
> that is likewise sequential writing.
>
> Reads on the other hand, to the extent that they go down to disk, will
> suffer the usual overhead associated with disk seeks.
>
> See http://wiki.apache.org/cassandra/ArchitectureInternals for details.
>
> --
> / Peter Schuller aka scode
>

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