Is there really a 10x difference between indexed CFs and non-indexed CFs?

On Mon, Jun 6, 2011 at 11:05 AM, Donal Zang <zangds@ihep.ac.cn> wrote:
On 06/06/2011 05:38, Jonathan Ellis wrote:
Index updates require read-before-write (to find out what the prior
version was, if any, and update the index accordingly).  This is
random i/o.

Index creation on the other hand is a lot of sequential i/o, hence
more efficient.

So, the classic bulk load advice to ingest data prior to creating
indexes applies.
Thanks for the explanation!

--
Donal Zang
Computing Center, IHEP
19B YuquanLu, Shijingshan District,Beijing, 100049
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