- users-list - monetdb.org

[MonetDB-users] Perl and MonetDB Xquery
by Peter van der Kamp 18 Aug '05

18 Aug '05

LS, As Perl is one of the main programming languages at our institute, I tried the Perl API with MonetDB-Xquery. I succeeded with sending mil statements (with the language parameter set to 'mil') to the server and getting the correct answer, but xqueries failed (with the language parameter set to 'xquery'). This was not a complete surprise as the documentation seems to be ambiguous ("MonetDB/XQuery for POSIX (Linux/Unix) platforms currently only supports MAPI (MonetDB API) to communicate with the XQuery engine."). Following the link to the API's: "Perl binding of the simple Monet API (Mapi) for MIL/SQL database interaction". So, I would like to know if my assumption that currently no xqueries are supported by the Perl API is correct. Peter

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[MonetDB-users] BerkeleyDB
by Rodrigo Schmidt 16 Aug '05

16 Aug '05

Has anyone compared the relative performance between MonetDB (MIL interface) and BerkeleyDB? If so, what were the results? Cheers, Rodrigo

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[MonetDB-users] Re: Support for group by <ordinal> and SQL OLAP functions
by Fabian (MonetDB Project) 12 Aug '05

12 Aug '05

(I'm sending this to the monetdb-users list, as it might help some other people too) Hi, Thanks for your interest in MonetDB/SQL. gustavo wrote: > ... What I´m missing mostly is support for group by a > number of a column. In this way it would be possible to group by na > expression without the use of a derived table (select from select). I don't exactly understand what you want to do. Can you give a concrete (SQL) example that shows what you want to do? I think that would help getting me to understand. > Another > thing that could boost MonetDb usage is SQL OLAP support like stddev, ranks, > running sums/averages, windowing support, rollup and cube. Most of what you mention require a different approach to the data I think. Like running sums or windowing support somehow require you to examine 'streams' of data, thus acting on data as soon as it comes in. I don't think SQL is yet up for this job, the best you can do is simply simulate it. I think CUBE was added to SQL-2003 and therefore might get included, but I don't think on the short term. However, a concrete list of wishes is always welcome! Thanks for your input!

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[MonetDB-users] JDBC driver
by Rodrigo Schmidt 12 Aug '05

12 Aug '05

I installed MonetDB_JDBC-1.2-Blunt-SR1.jar and I am getting the following problem when I try to load MonetDriver using class.forName(): java.lang.UnsupportedClassVersionError: nl/cwi/monetdb/jdbc/MonetDriver (Unsupported major.minor version 49.0). Does any of you know what the problem is? Cheers, Rodrigo

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[MonetDB-users] Problem configuring MonetDB/XQuery
by Peter van der Kamp 11 Aug '05

11 Aug '05

I successfully build MonetDB, prior to configure and build the XQuery front end. However, running configure for this front end stops with: Checking for Mx... no configure: error: No Mx found in PATH I try to build the Mx software, without success. Before continuing I would like to know if the XQuery front end really needs Mx. Thanks. Peter van der Kamp

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[MonetDB-users] inconsistent database
by Rodrigo Schmidt 10 Aug '05

10 Aug '05

Hi, While playing with SQL schemas (creating and eliminating them) I managed to put the database in an inconsistent state. Now I have a schema with nothing inside (neither users nor tables) and apparently I am not able to drop it. When I try, both database server and client crash with an internal error. Is there any monetdb tool that checks the database consistency and recovers it if a problem is identified? Cheers, Rodrigo

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[MonetDB-users] Different storage spaces
by Rodrigo Schmidt 10 Aug '05

10 Aug '05

Hello, In my application I have several processes in a server, each one managing different and non-related pieces of data, which I intend to store in MonetDB databases. As these processes are not related to each other, I would like to put their data in logically different storage spaces, like a different catalog or a different schema inside the database, if not in in different databases themselves. I am just starting with MonetDB and I do not know how I can create new databases, catalogs or schemas and what I should do to configure these things on the server. Can you give me some hints about it? FYI, my application is written in Java and I am using the JDBC interface to connect to the database. Cheers, Rodrigo

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[MonetDB-users] New
by rita kelly 08 Aug '05

08 Aug '05

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[MonetDB-users] speed comparison off inserts and deletes, and db size question
by Quartz 03 Aug '05

03 Aug '05

Hi, I'm not too familiar with the BAT concept. Regardless, I want to know more about the SQL equivalents. We have need for a 300 million recors DB of about 500 GB. We insert about 1000 records per seconds. or about 100 millions record per day, for 3 days. We 'roll' the data by time, deleting the tail end of the tables, but the the 'deletes' are too slow. So, we are looking at better DB or data storage patterns (one that would allow a quick DROP-table-like or file.delete() response time). So, as I look at MonetDB, I have some questions: 1-What is the insert speed relatively to other DBs? 2-What is the delete speed relatively to other DBs? 3-What is the insert speed degradation with the addition of indexes? 4-What is the delete speed degradation with the addition of indexes? Also, in the forum, I saw some discussions about size. We may remain on a 32 bits kernel, so: 5-The 2 gigs limit on BATs, is that records count is byte size? A performance constraint was also highlighted: "the performance degradation starts when MonetDB has to access BATs larger then the available memory" 6-In our case, with 300 millions records, how big would be the BATs? Last question, lucky 7: 7-Do you think MonetDB is at all a good choice for our high-thoughput highly volatile data? Thanks! ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs

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[MonetDB-users] Using MonetDB for financial time series analysis
by Joel Reymont 28 Jul '05

28 Jul '05

Howdy! I'm looking to use the framework for high-performance storing and querying of financial time series, i.e. ticks arriving from the exchange. I need to be able to store 500-1000 (or more) ticks per second and would like to be able to quickly find similar time series given a date range. I'm looking to create a cheaper alternative to www.kx.com with their KDB and K language. For each tick I need to store the datetime, symbol, trade type (bid/ask/trade), price and volume. How would I do a similarity search? I would like to select a portion of my stock chart (for example) and find subsequences in other stocks that match the pattern. What is the best way to take differences in scale be taken into account? Would I need to calculate the Euclidian distance myself? If I am to write wavelet or Fast Fourier Transform code, should I write it in MIL or use the Python/Perl/etc interface? Thanks for your help and please use the link in my signature to read up on my project. Thanks, Joel -- http://wagerlabs.com/uptick

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