September 2012 - users-list

[MonetDB-users] Announcement: New Jul2012-SP2 Bugfix release of MonetDB suite
by Sjoerd Mullender 21 Sep '12

21 Sep '12

The MonetDB team at CWI/MonetDB BV is pleased to announce the Jul2012-SP2 bugfix release of the MonetDB suite of programs. More information about MonetDB can be found on our website at <http://www.monetdb.org/>. For details on this release, please see the release notes at <http://www.monetdb.org/Downloads/ReleaseNotes>. As usual, the download location is <http://dev.monetdb.org/downloads/>. Jul 2012-SP2 bugfix release Java Module * Fixed a bug where DatabaseMetaData.getURL() did return null:0 for hostname:port. MonetDB5 Server * Changed the way nclients maximum was calculated to avoid 'out of client slots' errors way before the maximum was reached. Merovingian * Resolved a problem where monetdb could fail to start a database with the message "database 'X' started up, but failed to open up a communication channel". Bug #3134, comment #7. MonetDB Common * Fixed a bug in BATantijoin when either side is a singleton BAT. This fixes bug 3139. Bug Fixes * 3117: test sql/test/BugTracker-2011/Tests/history.Bug-2909.sql produces extra profiling output since changeset 817328b74e2f * 3134: Database gets killed by timeout during startup * 3139: Not equal evaluation does not work * 3144: Memleak when connecting to a database (mclient and mapi) * 3145: mclient error when enabling history * 3150: Multiple string equality tests fail to match (Test_JdbcClient)

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[MonetDB-users] time for ssbm
by guangliang peng 18 Sep '12

18 Sep '12

hi, my query schema is SSBM.My database size is 65G.There are five tables : lineorder 600038145 rows part 1400000 date 2556 supplier 1000000 customer 3000000 and my host have enough memory space up to 500G when i run query select sum(lo_extendedprice*lo_discount) as revenue from voc.lineorder, voc.dates where lo_orderdate = d_datekey and d_weeknuminyear = 6 and d_year = 1994 and lo_discount between 5 and 7 and lo_quantity between 26 and 35; the result is below | revenue | +===============+ | 2605756481323 | +---------------+ 1 tuple (6.2s) but if i delete the condition of " lo_discount between 5 and 7" the run result is more faster than the original one. query select sum(lo_extendedprice*lo_discount) as revenue from voc.lineorder, voc.dates where lo_orderdate = d_datekey and d_weeknuminyear = 6 and d_year = 1994 and lo_quantity between 26 and 35; +---------------+ | revenue | +===============+ | 7990711777299 | +---------------+ 1 tuple (410.451ms) at the same time ,if i delete the condition of "lo_quantity between 26 and 35" the run result is more faster than the original one too. query select sum(lo_extendedprice*lo_discount) as revenue from voc.lineorder, voc.dates where lo_orderdate = d_datekey and d_weeknuminyear = 6 and d_year = 1994 and lo_quantity between 26 and 35; +---------------+ | revenue | +===============+ | 7990711777299 | +---------------+ 1 tuple (463.617ms) i am confused and if the semijoin costs a lot of execution time ? Thank you for your help. best reguards, guangliang peng

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[MonetDB-users] Disk space cleanup policy
by Jukka 17 Sep '12

17 Sep '12

Hi, What is the disk space cleanup policy of MonetDb? If I remove all rows of table with delete command, the disk utilization of dbfarm is still the same. The storage() function is still reporting the same size for the table as before the delete command only count of rows was decreased to zero. Also executing drop table sql statement does not seem to release the disk space. -- Jukka

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[MonetDB-users] MonetDb and too many open files
by Jukka 17 Sep '12

17 Sep '12

Hi, How many files MonetDb is keeping open during runtime? I have running some test on MonetDb on RedHat 6 environment and faced the problem with the too many open files error during the loading phase after having several tables created to the database. I managed to avoid the current error with increasing the file handle limit: vi /etc/security/limits.conf #add for file handle #see lsof -p pid monetdb soft nofile 65536 monetdb hard nofile 65536 Now the system is running, but after 500 tables in MonetDb, I see about 17000 file handle listed with lsof -p command. The most of those are pointing to files in dbfarm folder. Is the files of all columns of all tables kept all the time? Is there formula to estimate the number file handles needed? Is there any limit how many tables or columns we can have in one MonetDb instance? The version used is "MonetDB Database Server v1.6 (Jul2012-SP1)" compiled from sources for RedHat 6. -- Jukka jukkakar(a)iki.fi

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[MonetDB-users] MonetDb slowing down
by Cory Isaacson 07 Sep '12

07 Sep '12

We have MonetDb running in the AWS cloud, with about 32GB of physical RAM. Our process uses COPY INTO every few minutes to load small chunks of data (usually 1000 rows at a time). That seems to work fine. There are a few users running queries against MonetDb, and now at least once/day we have to start/stop MonetDb. We see very high disk I/O (mainly I/O wait), so it appears that memory usage is high and does not get released. We are using the April 2012 release. The JDBC client is used for these queries. Overall MonetDb is doing a very good job, but this slowdown makes it appear unstable to end users. If there are any suggestions on how to improve this please let us know. cmi --

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[MonetDB-users] Connecting from DBLite.com
by Medha Atre 06 Sep '12

06 Sep '12

Hello, I have successfully installed and used MonetDB in the past as a standalone server, by connecting/querying through "mclient" running on the same machine where server is running. I was trying out web-based access, in which I was trying DBLite's simple web interface http://user.dblite.com (running on the browser on the same machine). My MonetDB server was compiled with "enable-sql", "enable-mserver5", and other optimization options. Not compiled with JDBC/ODBC though (but DBLite is a PHP based interface). "Control" is set to YES and "passphrase" is set to "monetdb" too. While the server is running, I can very well connect and query through command line mclient, but if I give "localhost", port as 50000 and default user/passwd "monetdb/monetdb" on the http://user.dblite.com interface, it keeps giving me "access denied" error. I am wondering what I am missing! Thanks. Medha

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[MonetDB-users] source code structure
by guangliang peng 06 Sep '12

06 Sep '12

hi, i prepare to look at the source code of monnetdb.Can you guys give me some advices which can help reduce the time on the source code .And what's the source code structure? thanks, guangliang

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[MonetDB-users] costmodel
by guangliang peng 05 Sep '12

05 Sep '12

hello, how do i show costmodel where i run a query ?because i want to know the internal execution of a query . thanks, guangliang

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[MonetDB-users] monetdb join path
by guangliang peng 05 Sep '12

05 Sep '12

I now still feel confused about join_path .I have tried the trace ,but the results show many lines with MAL language.It is very hard for me to find out the join path and order.can anyone help me?

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