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Sep 20, 2004 2:52:10 PM

arjohn
OpenRDF project lead
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New CVS branch: serql-extensions

Hi all,

We have created a new CVS branch called "serql-extensions" for Arjan Kleine. Arjan is an IT-student and is in his final year at the Free University of Amsterdam. He will be working on a number of extension to the SeRQL query language as part of his 6-months graduation project. Stuff he is planning to add to SeRQL includes:
  • Column aliases (i.e. "SELECT ... AS ..."),
  • Set operations like UNION, INTERSECT and MINUS,
  • Query nesting and quantification (e.g. IN-operator), and
  • Grouping and aggregation (COUNT, SUM, etc.).
More detailed info can be found in the attached action plan. Feel free to share any comments or suggestions with him using this forum.

Implemented features will be merged back into the HEAD of CVS on a per-feature basis.
----------------------------------------
Attachment PvA SeRQL extensions.pdf (126951 bytes) (Download Count: 549) (Planned SeRQL extensions)

----------------------------------------
Arjohn Kampman, OpenRDF project lead, Aduna
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Jan 24, 2005 1:34:33 PM

arjan
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Re: New CVS branch: serql-extensions

Hi all,

Here a status report about the SeRQL-extensions:

Finished extensions:
- column alias (AS)
- set operators (UNION/MINUS/INTERSECT)
- query nesting (IN)
- quantification (ANY/ALL)
- grouping (GROUP BY/HAVING)

They're not thoroughly tested, so do something about it and have fun! ;-)

Arjan.

attached the modified BNF for the "technically savvy" :-)
----------------------------------------
Attachment Modified BNF grammar.txt (3427 bytes) (Download Count: 68) (Modified BNF grammar.txt)

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Jan 24, 2005 2:37:35 PM

jeen
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Re: New CVS branch: serql-extensions

If anyone wants to try these out: they are not yet in an official release, but can be found in Sesame CVS, in the branch 'serql-extensions'. Be aware that this branch is based on Sesame 1.0 code and may contain bugs that have been fixed since. Don't replace your existing Sesame server just yet, but testing feedback would be very welcome biggrin
----------------------------------------
Researcher at AFSG - Wageningen UR
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Feb 3, 2005 11:17:15 PM

ondrej
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Re: New CVS branch: serql-extensions

Hi,
I was playing with extensions in SeRQL and they are really great.

During my testing I only encounter two problems:

1. grouping

"group by" according to modified BNF


select bike, price
from {id} bike:hasName {bike};
bike:hasPrice {price}
group by bike


Error: Encountered "by" at line 13, column 7. Was expecting: "{" ...

"groupBy" according to "serql.jj" (there is "groupBy" as "terminal symbol")


select bike, price
from {id} bike:hasName {bike};
bike:hasPrice {price}
groupBy bike


Error: Encountered "groupBy" at line 13, ...

Are above-mentioned queries bad?
Or grouping is not supported yet?

2. problem with "any", "all" worked well

(that's quite artificial query...):


select bike, price
from {bike} bike:hasPrice {price}
where price > any
(select price
from {bike} bike:hasPrice {price}
where price < "20"^^<xsd:int>)


Imagine you have:
bike: price:

bike:offer1 "25"@en
bike:offer2 "21"@en
bike:offer3 "18"@en
bike:offer4 "30"@en
bike:offer4 "40"@en
bike:offer5 "5"@en
bike:offer6 "15"@en
bike:offer7 "5"@en
bike:offer8 "5"@en
bike:offer9 "5"@en

I would say that the result should be all except bikes with price "5".
But the result is nothing.
Is it right or no?

In any case, well-done Arjan biggrin

regards,
ondrej
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Feb 16, 2005 2:17:39 PM

jeen
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The Netherlands
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Re: New CVS branch: serql-extensions

FYI, I've merged the 'serql-extensions' branch back into the CVS trunk. Also, a number of bugs were fixed and small optimizations were implemented. Further testing is still required but on the surface things are looking quite good.
----------------------------------------
Researcher at AFSG - Wageningen UR
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Mar 8, 2005 9:49:15 AM

bartman
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Re: New CVS branch: serql-extensions

 
Hi all,

Here a status report about the SeRQL-extensions:

Finished extensions:
- column alias (AS)
- set operators (UNION/MINUS/INTERSECT)
- query nesting (IN)
- quantification (ANY/ALL)
- grouping (GROUP BY/HAVING)

They're not thoroughly tested, so do something about it and have fun! ;-)

Arjan.

attached the modified BNF for the "technically savvy" :-)


Do we have a count-operator in the extensions? The grammar includes the operator, but it does'nt seem to be implemented.

This would clean up some really messy code in my application...

Bartman
----------------------------------------
[Edit 1 times, last edit by bartman at Mar 8, 2005 10:52:51 AM]
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Mar 8, 2005 9:54:44 AM

jeen
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The Netherlands
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Re: New CVS branch: serql-extensions

Unfortunately Arjan did not have the time to finish this, so the count() operator is not yet implemented (nor is the group by and some other planned extensions). We do intend to include these before the release of Sesame 1.2 though.
----------------------------------------
Researcher at AFSG - Wageningen UR
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Nov 24, 2005 3:36:54 PM

manzikki
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Re: New CVS branch: serql-extensions

Hi,

 
Unfortunately Arjan did not have the time to finish this, so the count() operator is not yet implemented (nor is the group by and some other planned extensions). We do intend to include these before the release of Sesame 1.2 though.


I'd like to see if I can make myself understand the query code. Of course in the nicest case I could contribute some code (but no promises). So, starting with a naive, non-optimized version of COUNT would be fun.

To start with, is it enough to modify files in src/org/openrdf/sesame/query/serql? How should I introduce the operator as a terminal/reserved word in the language (apparently not in serql.jj.. or then I need JavaCC for compilation).

Marko
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Nov 25, 2005 10:26:36 AM

arjohn
OpenRDF project lead
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Re: New CVS branch: serql-extensions

 
I'd like to see if I can make myself understand the query code. Of course in the nicest case I could contribute some code (but no promises). So, starting with a naive, non-optimized version of COUNT would be fun.

Would be great.

 
To start with, is it enough to modify files in src/org/openrdf/sesame/query/serql? How should I introduce the operator as a terminal/reserved word in the language (apparently not in serql.jj.. or then I need JavaCC for compilation).

JavaCC is used to generate the SeRQL parser, so yes, you will need to edit this file. Don't bother trying to understand the generated code, it's hardly readable.

This code, however, is only the parser-side of the story. The Sail Query Model also needs to be extended, as this is what the parser uses to create an object model of the query. These classes can be found in package org.openrdf.sesame.sail.query.
----------------------------------------
Arjohn Kampman, OpenRDF project lead, Aduna
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Jan 17, 2006 9:46:08 AM

manzikki
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Re: New CVS branch: serql-extensions

Hi,

sorry for the time lag. I managed to write something the resembles COUNT, but I need to ask something primitive, too, since I did not find a specific "developer document" (is there one, other than http://www.openrdf.org/doc/sesame2/system/ ?) and did not see anything in build.xml:
how do I write a new new test case in test/* and what is the ant command that executes the tests?

I'm using the source code 2.0-alpha-1.

Marko
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