Hi,
I am getting some strange exceptions using MonetDB JDBC 1.8/1.9, and I
decided to look into the code. While inspecting the code I came across
these strange lines in MonetConnection.executeQuery(String[] templ,
String query) method
(http://dev.monetdb.org/hg/MonetDB/file/718da8ca0a1a/java/src/nl/cwi/monetdb…).
In my case, these lines are executed for sure when doing a batch
insert. So, suppose that the batch contains the following commands (as
constructed by the MonetStatement.executeBatch() method):
exec 1(1, 957339737330229055);
exec 1(2, 278262503670654331);
exec 1(805306369, 3763943296910752235)
The lines in question take the above commands as a string, prepend a
's' character and append a ';' at the end. The resulting commands,
which are written in the server's socket, are the following:
sexec 1(1, 957339737330229055);
exec 1(2, 278262503670654331);
exec 1(805306369, 3763943296910752235);
First of all, I am not familiar with the internals of JDBC drivers.
Taking this into account, is this what it should be? From a symmetric
point of view, I would assume that the correct would be the following:
sexec 1(1, 957339737330229055);
sexec 1(2, 278262503670654331);
sexec 1(805306369, 3763943296910752235);
That is, it should prepend a 's' character before an exec command.
Last, are these exec commands (with or without a prepending 's')
specific to MonetDB? In either case, is there any documentation to get
familiar with their meaning?
Thanks a lot,
Babis
Subject:
Adaptive indexing techniques for modern database systems.
The Centrum Wiskunde & Informatica (CWI) has a full time vacancy for a
talented PhD candidate in the Database Architectures group
(http://www.cwi.nl/en/research-groups/Database-Architectures).
The position is in the broad area of adaptive indexing techniques for modern database systems.
Adaptive indexing is a major challenge in database research; it tries to completely alleviate the need for
indexing and tuning steps leading to database systems that require no physical design set-up and can
cope immediately with any workload. This leads to database systems that are instantly usable and thus
more applicable to numerous new applications that now consider databases too slow, too complex and too old.
This position will focus specifically on adaptive indexing for extremely large databases where traditional indexing
represents a major bottleneck.
The Database Architectures group is one of the world-wide leading groups in
system-oriented database research, e.g., it received the 10-year best paper
award at VLDB 2009 for their pioneering research on hardware-aware database
technology and the column-store model and the
2011 ACM SIGMOD Jim Gray Dissertation award for the database cracking work.
The group has a unique methodology
that combines fundamental database research with active participation of all
group members in database engineering, centred around the open-source
analytical database system MonetDB (http://www.monetdb.org/).
An internship at one of the partnering
database research labs world-wide is considered part of the PhD track.
REQUIREMENTS
The PhD candidates must have a master degree in computer science (or a 5 year diploma),
(specialisation databases, distributed systems, software engineering)
mathematics, or related fields. Preferable qualifications for candidates
include proven research talent, system programming skills (C/C++),
practical experience with using and implementing database systems,
and software development in a team.
Candidates are expected to have an excellent command of English,
and good academic writing and presentation skills.
CENTRUM WISKUNDE & INFORMATICA (CWI)
Founded in 1946, the Centrum Wiskunde & Informatica (CWI) is the national
research institute for mathematics and computer science in the Netherlands.
It is located at the Science Park Amsterdam and is part of the “Netherlands
Organisation for Scientific Research” (NWO). The institute is
internationally focused and renowned for its high quality research, a
substantial fraction of which is carried out in the framework of
(inter)national programs. Over 160 researchers conduct pioneering research
and share their acquired knowledge with society. More than 30 researchers
are employed as professors at universities. The institute has generated
twenty-one spin-off companies.
CWI maintains excellent relations with industry and the academic world, both
in the Netherlands as well as abroad. After their research careers at CWI,
an increasing number of young staff members find employment in these sectors
or in spin-off companies that are based on research results from CWI. Of
course, library and computing facilities are first-rate. CWI's
non-scientific services to its personnel include career planning, training
and courses, assistance in finding housing, and tailor-made solutions to
problems that may occasionally arise.
TERMS AND CONDITIONS
The terms of employment are in accordance with the Dutch Collective Labour
Agreement for Research Institutes ("CAO-onderzoeksinstellingen"). Moreover
CWI offers attractive working conditions, including flexible scheduling and
help with housing for expat employees.
The gross monthly salary, for an employee on a full time basis, is €2,037
during the first year and increases to €2,610 over a four year period. CWI
also offers excellent and flexible terms of employment, including an
employee pension fund.
INFORMATION
Additional information can be obtained from:
dr. Stratos Idreos, email stratos.idreos(a)cwi.nl, telephone +31(0)20 592 4169.
or dr. Stefan Manegold, email stefan.manegold(a)cwi.nl, telephone +31(0)20 592 4212,
or prof. dr. Martin Kersten, email martin.kersten(a)cwi.nl, telephone +31(0)20 592 4066.
APPLICATION
Please send your application before 31 July 2011 to: pd(a)cwi.nl.
Applications should include a detailed CV, a motivation letter, a list of
your M.SC. courses and grades, a copy of your master thesis, and preferably
a list of publications.
Hi,
I'm playing with parallization of databases and I am a little confused about my result on MonetDB.
Scenario: 15 Millions of Entries and i want to find the number of entries where the attributes are in a certain sector (i know, a simple select would do the work but i wanted a simple example)
i have java code that get all 15 Mio. Data from the database via JDBC and iterates over them with a loop without multithreading. --> 13 ms
then i created a stored function:
CREATE FUNCTION isInRangexy(x DECIMAL(10,7), y DECIMAL(10,7)) RETURNS BOOL
BEGIN ATOMIC
IF x > 50 AND y < 50 THEN
RETURN true;
ELSE
RETURN false;
END IF;
END
Then I call it with: SELECT COUNT(*) FROM location WHERE isInRange(x,y)
It works, but it is more than 3 times slower than the first java option. I had thought i would get benefit from the fact that i don't need to transfer all the data to the application and of some parallelization and other optimization from monetdb.
Did I made a mistake? Can I use another example to get the anticipated results?
thanks,
michael
Hi,
is it possible to achieve the following using SQL stored procedures à la "CREATE PROCEDURE XYZ"?
I want to write a function that iterates over a table and adds 2 on a certain attribute. i am realizing that i could do this by an UPDATE, but I wanted to see, whether it would be executed more parallel inside a stored procedure.
Is there a way of formulating this in a procedure? do i need to define a function in MAL? would this result in more parallel execution?
thanks,
michael
Hi All,
I am going to build a DW based on MonetDB. After check on the internet I
found that MonetDB does not do data compression. Same data set in MonetDb is
much bigger than MySQL
and infoBright.
Are there any plan to do data compression in the MonetDB?
Yours sincerely,
Ken Cheng
Hello everyone,
After visiting the MonetDB website, I didn't saw any information about the
windowing functions of SQL (ranking, selecting max according to a defined
order, etc.)
A (very) short introduction can be found on wikipedia:
http://en.wikipedia.org/wiki/Select_%28SQL%29#Window_function
I know it is implemented into PostGreSQL, Oracle and Microsoft SQL Server.
Is there any chance to see this function in MonetDB in the future ?
Thanks in advance, sorry for my poor english ... :(
Fabian Pijcke
CWI is an internationally renowned research institute in mathematics and
computer science, located in Amsterdam, The Netherlands.
The focus is on fundamental research problems, inspired by societal needs.
Research is carried out in 18 research groups and a substantial fraction
is carried out in the framework of (inter)national programs.
VACANCY
CWI has a vacancy for a talented PhD candidate in the DB Architectures group
(http://www.cwi.nl/en/research-groups/Database-Architectures).
DISTRIBUTED DATABASE ARCHITECTURES FOR SCIENCE APPLICATIONS
The Database Architectures group is one of the world-wide leading groups in
system-oriented database research, e.g., it received the 10-year best paper
award at VLDB 2009 for their pioneering research on hardware-aware database
technology and the column-store model. The group has a unique methodology
that combines fundamental database research with active participation of all
group members in database engineering, centered around the open-source
analytical database system MonetDB (http://www.monetdb.org/).
You will be expected to write both papers and contribute to this code base.
The focus of the group is on hard core data management and for this position
specifically on database architectures to support large scale scientific
applications in the context of the SciLens project (http://www.scilens.org).
The goal is to leverage the potential power of a 330 node dedicated database
machine to improve science in, e.g., astronomy and seismology.
(http://www.scilens.org/content/platform)
CWI maintains excellent relations with industry and the academic world, both
in the Netherlands as well as abroad. An internship at one of the partnering
database research labs world-wide is considered part of the PhD track.
After their research careers at CWI, many staff members find employment in
these sectors or in spin-off companies based on research results from CWI.
Of course, library and computing facilities are first-class.
CWI's non-scientific services to its personnel include career planning,
training and courses, assistance in finding housing, and tailor-made
solutions to problems that may occasionally arise.
REQUIREMENTS
The PhD candidates must have a master degree in computer science,
(specialization distributed systems, database, software engineering)
mathematics, or related fields. Preferable qualifications for candidates
include proven research talent, system programming skills (C/C++),
practical experience with database systems, and software development in a team.
One should bring good academic writing and presentation skills.
Candidates are expected to have an excellent command of English.
TERMS AND CONDITIONS
The terms of employment are in accordance with the Dutch "CAO-onderzoeksinstellingen".
Moreover, CWI offers attractive working conditions, including flexibility
and help with housing for foreigners.
The gross monthly salary (on a full time basis) will be ⬠2,037 during
the first year and will reach ⬠2,610 during the fourth year.
INFORMATION
Additional information can be obtained from
prof.dr. Martin Kersten, email martin.kersten(a)cwi.nl, telephone +31(0)20 592 4066,
or dr. Stefan Manegold, email stefan.manegold(a)cwi.nl, telephone +31(0)20 592 4212.
--
| Stefan.Manegold @ CWI.nl | DB Architectures (INS1) |
| http://CWI.nl/~manegold/ | Science Park 123 (L321) |
| Tel.: +31 (0)20 592-4212 | 1098 XG Amsterdam (NL) |