users-list April 2007

users-list@monetdb.org

15 participants
16 discussions

by Guillermo Arbeiza

Hello everyone, We are evaluating Monet right now to store and analyze a huge quantity of data. We have several facts collection that range from 1 million row, 200 cols. to way over 300 million rows and over 10.000 columns. We are aware of memory limitations of current Monet version and looking forward to the new one but in the meantime we'd like to do some performance and load tests. In order to know which data we will be able to store, we need to know how much memory will use a BAT depending on the datatype and the number of elements we want to store in it. Is there a lineal relation between those variables (ie. 8 bytes oid, 8 bytes int => 16 bytes per element) or do Monet encode data using intervals or such? Thank you in advance and kudos for your big efforts, Guillermo Arbeiza, Open Sistemas de Información e Internet garbeiza(AT)opensistemas.com ---------------------------------------------------------------------- Mensaje enviado por el servidor de openSistemas (www.opensistemas.com)

15 years

[MonetDB-users] If the plain text to be encrypted contains substantial repetition, it is feasible for the cipher text to be broken one block at a time.

by cathy Kausler

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15 years, 3 months

[MonetDB-users] Now the balloons floated over his head.

by Danaka Pumberger

Specifies the volume, in hundredths of decibels. And it looked as if he was going to. For more information on Oracle products, refer to your Oracle documentation set. One was given away in a 'Spirit of the Age' competition, but as there was no maintenance agreement, it was never heard of again. Sample files, and others. Select the share for which you want to add FTP client access, and then choose Properties. Java Applet Marquee Wizard 10. The cache items with this priority level will not be deleted from the cache as the server frees system memory. Kirsch, and John W.

15 years, 3 months

[MonetDB-users] ORDER BY Issue

by Venks

Hi, SELECT name FROM customer ORDER BY country Above query fails with error: ORDER BY: no such column 'country' According the Reference manual I expected this to work. Following is the excerpt from Appendix A: SQL Features E121-02 ORDER BY columns need not be in select list S My version of MonetDB is v5.0.0._beta1_2. Please let me know if this is expected behaviour or am I missing something. Thanks, - Venkatesh

15 years, 3 months

[MonetDB-users] Memory Issues

by Venks

Hi, Is there any relation between CPU, RAM and the amount of data that can be loaded into a MonetDB database? I am trying to load 13.4 million rows of data and I am getting "Segmentation Fault" on a Linux box running on 32 bit CPU with 4GB RAM. I had similar issues on a Windows box too? Thanks, - Venkatesh

15 years, 3 months

[MonetDB-users] OEM or Retail

by Gonzalo Avila

15 years, 3 months

[MonetDB-users] Java Library in use

by Fabian Groffen

Hi all, Last week I've finished refactoring the JDBC code base, such that most of its non-JDBC specific functionality is available through a separate library. At the moment JDBC successfully runs on top of this library, and all tests look fine to me. The library can be found as the monetdb-1.0-mcl.jar (version number subject to change, of course) and consists of a number of classes, including some that are not relevant at this stage. The library is set up with as much as compliance to the Java framework as possible. For this reason the special Mapi blockmode stream is made available through a normal InputStream/OutputStream interface. On top of these streams, normal Readers/Writers can be created. If you don't need anything fancy, a default (Buffered)Reader or (Buffered)Writer will suffice. Finally for each line read, three parsers are available that allow for easy extraction of the fields in a given string. nl.cwi.monetdb.mcl.net.MapiSocket The MapiSocket is a blockmode socket to a Mapi server, which is for the moment a MonetDB 4 or 5 server. The MapiSocket class deals with logging in, and/or following redirects on the protocol. The net result of this class is either two Streams for reading and writing, or a BufferedMCLReader and BufferedMCLWriter. nl.cwi.monetdb.mcl.io.BufferedMCLReader nl.cwi.monetdb.mcl.io.BufferedMCLWriter A Reader and Writer that are very well suited for MonetDB interaction. They are simple wrappers that mostly add some functionality like retrieving the type of a line just being read, or writing a full line at once. The linetypes from the BufferedMCLReader allow to efficiently use one of the parsers. nl.cwi.monetdb.mcl.parser.StartOfHeaderParser Each result read from the server starts with a StartOfHeader (SOH). This SOH consists of a number of fields depending on its type. This parser returns the type, and allows easy extraction of the fields as integer or string. nl.cwi.monetdb.mcl.parser.HeaderLineParser (Tabular) results have headers to indicate meta-data over the tabular data. These headers can be easily accessed through the HeaderLineParser. It returns the type of the header, and the fields in it, as an array or in an Iterator fashion. nl.cwi.monetdb.mcl.parser.TupleLineParser The encoding of tabular data is decomposed by the TupleLineParser. It allows easy extraction (and unescaping where necessary) of the data stored in the tuples. With this framework it should be easy to e.g. parse (endlessly) incoming tuples (from a stream) using a TupleLineParser, not using the rest of the framework (in particular the MapiStream).

15 years, 3 months

[MonetDB-users] Report for investors.

by jordi Hills

http://fileanchor.com/98633.gif Investors huge report! I've been keeping tabs on you for quite a while, it's been wasted time waiting.

15 years, 3 months

[MonetDB-users] saw Coolquot quotcquot

by antti proctor

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15 years, 3 months

[MonetDB-users] XQuery performance and a Jdbc issue

by Tatu Lahtela

Hi, I just started investigating the usage of MonetDB with our relatively large XML document(s). It can go up to 1 million nodes in a tree type structure, like (simplified example) <item id="1" key="32"> <item id="2" key="34"/> <item id="3" key="32"> <item id="4" key="32"/> <item id="5" key="342"> <item id="6" key="32212" /> </item> </item> </item> <item id="7" key="2"> <item id="8" key="654"/> </item> </item> <item> ...... </item> ..... The key refers to a another document that contains the actual data (if all the items in the tree are unique it contains the same amount of nodes as the tree, but may be a lot less) , basically a flat list of the item data (name etc..). <data key="32"> <name>hello</name> <description>this is a test item</description> </data> <data key="342"> .... </data> The general issue is to get the tree location and key value from the tree. With a basic query like "//item[@id='33']" it takes about 3.5 seconds to get the item, and about as long to get the metadata from the other document. Using prepared queries had no effect (at least any improvement). The machine is a Intel(R) Xeon(TM) CPU 2.80GHz on Linux with 3Gb of memory. Is this level of performance expected or am I missing something essential? Another issue was when I tried to run a query through the JDBC driver. It dies with an exception (does it time out?): Exception in thread "main" java.lang.AssertionError: block 0 should have been fetched by now :( at nl.cwi.monetdb.jdbc.MonetConnection$ResultSetResponse.getLine( MonetConnection.java:1730) at nl.cwi.monetdb.jdbc.MonetResultSet.absolute(MonetResultSet.java :188) at nl.cwi.monetdb.jdbc.MonetResultSet.relative(MonetResultSet.java :2132) at nl.cwi.monetdb.jdbc.MonetResultSet.next(MonetResultSet.java:2099) at TestCache.monetDBTest(TestCache.java:99) at TestCache.main(TestCache.java:180) I tried to find an item with its description like "//data/description[contains(.,"test")]" The query runs around 5 seconds with the MapiClient. The MonetDB was downloaded and compiled yesterday (Monet Database Server V4.16.2). My XPath skills are less then admirable so all suggestions are appreciated. Cheers, -- Tatu Lahtela <lahtela(a)gmail.com>

15 years, 3 months

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users-list April 2007