users-list March 2008

users-list@monetdb.org

19 participants
20 discussions

by Matt Magoffin

Hello, I am interested in evaluating MonetDB/XQuery. I have some XML collections for a project I work on that are of 1-2 million individual XML documents for which I use XQuery to access for OLAP style reporting operations. This is a Java-based project, and while working on this project I developed a thin XQuery-centric API so that I could evaluate/use many different XQuery implementations, which my company released as an open source project called Xaj (http://sourceforge.net/projects/xaj). Currently I am using a Berkeley DB XML implementation, but am interested in exploring other options. I'd like to implement a MonetDB version of this API now, but I am having some difficulty finding out how to effectively access MonetDB through Java. So far I was able to use the MonetDB JDBC driver to construct XQuery statements and get XML results, and also I was able to construct MonetDB pf:add-doc() statements to add documents, but I am wondering if this is the best approach (and if so, how to add documents to a remote MonetDB server using the pf:add-doc() mechanism). The API I am trying to implement you can view here, to give you an idea what I'm trying to do: http://xaj.svn.sourceforge.net/viewvc/xaj/xaj/src/net/sf/xaj/XmlDb.java?rev… It was somewhat modeled after the defunct XML:DB API, but focused just on add/store/XQuery operations. Any help/advise would be greatly appreciated! -- m@

13 years, 11 months

[MonetDB-users] db log shrink

by Colin Foss

Is there any method, besides restarting the database, of shrinking the sql log file? When I am performing a large set of large inserts (via COPY INTO) the log file gets very large. I wish there was a way to cycle the log file. Also during these large batches of inserts the database server becomes less and less responsive until I am forced to restart the server. Upon restart and the normal recovery monet returns to a very responsive state.

14 years, 3 months

[MonetDB-users] linux flavor

by mobigital1

>From my testing of the windows 64 bit port it seems that may be the linux version is a bit more stable to run? (due to specifics of memory mapped file implementations)? can anyone suggest what flavor of linux is best to use to load most data? also the one that's easy to run under vmware? -- View this message in context: http://www.nabble.com/linux-flavor-tp15860790p15860790.html Sent from the monetdb-users mailing list archive at Nabble.com.

14 years, 3 months

[MonetDB-users] blobs performance

by Henrik Vendelbo

I am working through the options for clustered file management. Normally I would expect fairly poor performance of binary file storage in a database. Hence I would favor using the file system, and sync across the machines in the cluster. Being quite different from common relational implementations, how well does Monet handle blobs of 1-10Mb? As a side question is there a support for multi-master replication? The technology looks really impressive, I hope to be able to base my future projects on MonetDB Thanks, Henrik

14 years, 4 months

[MonetDB-users] !IOException:mal_mapi.listen When Starting MonetDB5 SQL Server

by kevin.haas＠openbi.com

When I try to start the MonetDB5 Server, I get the following error: # MonetDB server v5.4.0, based on kernel v1.22.0 # Serving database 'demo' # Compiled for i686-pc-win32/32bit with 32bit OIDs dynamically linked # Copyright (c) 1993-2008 CWI, all rights reserved # Visit http://monetdb.cwi.nl/ for further information #warning: please don't forget to set your vault key! #(see C:\Program Files\CWI\MonetDB5\etc\monetdb5.conf) !IOException:mal_mapi.listen:Creation of stream socket failedi: Unknown error #function user.main():void; ##library logger; # alarm.prelude(); ##command bat(ht:int, tt:int) :bat[:any_1,:any_2] ##address BKCnewBat_default ##comment "Creates a new empty transient BAT with head- and tail-types ## as indicated."; ##command bat(ht:int, tt:int, size:lng) :bat[:any_1,:any_2] <EDITED FOR BREVITY> ##comment "Execute the XQuery against the elements #end main; # MonetDB/SQL module v2.22.0 loaded > This does not seem like a "good" error. Any tips on how to correct? -- View this message in context: http://www.nabble.com/%21IOException%3Amal_mapi.listen-When-Starting-MonetD… Sent from the monetdb-users mailing list archive at Nabble.com.

14 years, 4 months

Re: [MonetDB-users] Database dump does not support schemas

by McKennirey.Matthew

14 years, 4 months

[MonetDB-users] Clustered Index and Merge Join

by Michael Schmidt

I have two tables of the form R1(x INTEGER, y INTEGER) R2(x INTEGER, y INTEGER) where x and y both are NOT NULL and may both contain duplicate values (however, the combination (a,b) is unique). My questions are the following: a.) Is there a possibility to create a /clustered/ index on the x-column (or a clustered combined x-y index?). I could also create a PRIMARY KEY on (x,y). Would this result in a clustered index? Is there any command to find out which indices are clustered? b.) Does MonetDB support MergeJoins? I.e., assume I have a clustered index on columns R1.a and R2.a and perform a join on these columns, will this join be realized by an efficient merge join? Best regards, Michael

14 years, 4 months

[MonetDB-users] MonetDB XQuery Server Startup Error

by Sprattling, Roderick L.

After installing the Win32 version of MonetDB XQuery as single-user, making no changes to MonetDB.conf, and attempting to run MXQserver.bat, I get this output: C:\Program Files\CWI\MonetDB4>MXQserver.bat # MonetDB Server v4.22.0 # based on GDK v1.22.0 # Copyright (c) 1993-2008, CWI. All rights reserved. # Compiled for i686-pc-win32/32bit with 32bit OIDs; dynamically linked. # Visit http://monetdb.cwi.nl/ <http://monetdb.cwi.nl/> for further information. # PF/Tijah module v0.5.0 loaded. http://dbappl.cs.utwente.nl/pftijah <http://dbappl.cs.utwente.nl/pftijah> !ERROR: MAPIlisten:creation of stream socket failed !OS: A blocking operation is currently executing. Since MXQserver.bat simply issues the command "Mserver.bat --dbinit='module(pathfinder);'", I ran that command directly, and to my surprise the server makes it to its own command line: # MonetDB Server v4.22.0 # based on GDK v1.22.0 # Copyright (c) 1993-2008, CWI. All rights reserved. # Compiled for i686-pc-win32/32bit with 32bit OIDs; dynamically linked. # Visit http://monetdb.cwi.nl/ for further information. MonetXDB> In this second case, the mclient cannot connect (even when I set server and client ports to something other than 50000,) nor is the admin GUI available on port 50001. So my questions are: Why does the server report a socket creation failure from the MXQserver.bat script? Why is no failure reported when the Mserver.bat script is run directly? And why is the server instance that comes up with Mserver.bat unconnective? I've sought answers from the documentation, Googleverse and the MonetDB-users archive, but found nothing. Thanks in advance for any help you can provide. Rod

14 years, 4 months

[MonetDB-users] Database dump does not support schemas

by McKennirey.Matthew

14 years, 4 months

[MonetDB-users] COPY INTO using a schema fails

by McKennirey.Matthew

I was wondering if the COPY command does not support schemas? CREATE TABLE test ( column1 VARCHAR(32), column2 VARCHAR(32) ); COPY INTO test FROM '/location/file.csv' USING DELIMITERS ',', '\n'; works fine CREATE SCHEMA abc; CREATE TABLE abc.test ( column1 VARCHAR(32), column2 VARCHAR(32) ); COPY INTO abc.test FROM '/location/file.csv' USING DELIMITERS ',', '\n'; fails with !SQLException:sql:table test not found !SQLException:importTable:failed to import table INSERT into abc.test VALUES(one,two) works fine

14 years, 4 months

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users-list March 2008