Hi Baraa,
you are right. MonetDB is a pure column store, and consequently does only keep a columnar (vertically decomposed) version of all tables, but no extra row-wise copy. Columns are "joined" into rows only when the final query result is returned to the client.
Best, Stefan
----- Original Message -----
Martin Thank you very much for this interesting documentation. I already saw the explain command and (if I correctly understood it) it seems that MonetDB does not store a complete copy of the original table (in a row-oriented fashion). I find that surprising to execute all these joins (I have a table with 227 column) in such short time. that's why I suppose that MonetDB may store a copy of the whole table in row-oriented model.
Thank you to correct me if I misunderstood something.
Baraa
Date: Sun, 9 Nov 2014 23:25:06 +0100 From: Martin.Kersten@cwi.nl To: users-list@monetdb.org Subject: Re: MonetDB joins
On 09/11/14 23:09, baraa Mohamad wrote:
Hello,
For time see: https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/QueryTiming For the rest, study the plans produced with PLAN/EXPLAIN/ and TRACE sql commands.
I'd like to know if MonetDB stores a copy of the whole table in order to reduce the joins between columns when doing select *. In fact, I'm doing a research for PhD and I appreciate the query execution time delivered by MonetDB over huge tables :)
Thanks in advance, Baraa
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