Hi, following the multi-tier optimization strategy of MonetDB (cf., e.g., http://repository.cwi.nl/search/fullrecord.php?publnr=11170), MonetDB/XQuery does both XQuery-specific (data oblivious) compile-time optimization in the Pathfinder compiler (cf., e.g., Torsten Grust. "Purely Relational FLWORs." Proceedings of the ACM SIGMOD 2nd International Workshop on XQuery Implementation, Experience and Perspectives (XIME-P 2005), Baltimore, MD, USA, June 2005.), and run-time optimization in the MonetDB column-store kernel, e.g., choosing the most efficient algorithm and implementation for each binary algebra operator given its actual inputs (the latter is independent of the logical data model). For an overview of MonetDB/XQuery, see e.g. http://repository.cwi.nl/search/fullrecord.php?publnr=15553 For a complete list of Pathfinder-related literature, see http://www-db.informatik.uni-tuebingen.de/research/pathfinder/publications You might want to use "Pathfinder: XQuery Off the Relational Shelf." Torsten Grust, Jan Rittinger, Jens Teubner. Bulletin of the IEEE Technical Committee on Data Engineering. Special Issue on XQuery Processing: Practice and Experience. Vol. 31, No. 4, December 2008. as starting point and let the references guide you to the topics the you're most interested in. For a complete list of MonetDB-related literature, see http://monetdb.cwi.nl/Development/Research/Articles/ Stefan ps: The XQuery run-time optimization as presented in http://repository.cwi.nl/search/fullrecord.php?publnr=14193 is not (yet?) available in the open-source version of MonetDB/XQuery. On Sun, Mar 07, 2010 at 01:58:59AM +0530, anshul gangwar wrote:

hello,           I just want to know about current monetdb version. Whether it does any optimization at compile time or not or it fully does at run time only. where can i get the information about the optimization strategy of monetdb. May be the specific src code file to refer of monetdb. can you please refer some research papers on monetdb optimization strategy etc.

On Sat, Mar 06, 2010 at 07:27:09PM +0530, anshul gangwar wrote:

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how can we get the estimate of the size of result of query based on any two attributes with varying rangeAnshul

Well, I guess you'd need to browse the related research literature for XML/XQuery cost modeling / result size estimation techniques --- however, to my knowledge that area is not yet as well charted and understood as cost modeling / result size estimation for relational algebra and SQL.

Of course, the details highly depend on your XML document structure and data distribution as well as the shape and characteristics of your XQuery queries ...

Stefan

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On Sat, Mar 06, 2010 at 11:32:03AM +0530, anshul gangwar wrote:

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--- On Fri, 5/3/10, Martin Kersten wrote:

From: Martin Kersten Subject: * Re: [Monetdb-developers] need help in monetdb xquery interface To: "anshul gangwar" Date: Friday, 5 March, 2010, 11:26 PM

anshul gangwar wrote:

...

hello ,            I want to know whether there is any expression or command or anything equivalent to explain sql construct. Also What is the way to There is material for you to study on the website: http://monetdb.cwi.nl/SQL/Documentation/SQL-Runtime-Features.html http://monetdb.cwi.nl/SQL/Documentation/EXPLAIN-Statement.html#EXPLAIN-State... get histogram statistics i.e way to find that histogram exists on attribute or not through Xquery interface. not through sql . MonetDB does not rely on separate statistics tables.

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  Please reply as soon as possible.

thank you.

Actually i want the xquery construct equivalent to sql explain construct and

MonetDB/XQuery does not provide such feature.

To see the equivalent of the SQL EXPLAIN output, i.e., the MIL plan generated from your XQuery query, you need to use the Pathfinder stand-alone compiler "pf"; see     `pf --help` and/or     `pf --fullhelp` for details.

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so how it simulates histogram features i.e to get that percentage of query etc.

Like MonetDB/SQL also   MonetDB/XQuery does not rely on separate statistics such as histograms.

Stefan

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