November 2013 - users-list

TypeException:user.main[2]:'A0' may not be used before being initialized
by Ruben Silva 08 Nov '13

08 Nov '13

Dear MonetDB users, Have you experienced anything like this before? TypeException:user.main[2]:'A0' may not be used before being initialized. Stacktrace follows: java.sql.SQLException: TypeException:user.main[2]:'A0' may not be used before being initialized at nl.cwi.monetdb.jdbc.MonetConnection$ResponseList.executeQuery(MonetConnection.java:2535) at nl.cwi.monetdb.jdbc.MonetConnection$ResponseList.processQuery(MonetConnection.java:2284) at nl.cwi.monetdb.jdbc.MonetStatement.internalExecute(MonetStatement.java:508) at nl.cwi.monetdb.jdbc.MonetStatement.execute(MonetStatement.java:349) at nl.cwi.monetdb.jdbc.MonetPreparedStatement.<init>(MonetPreparedStatement.java:118) at nl.cwi.monetdb.jdbc.MonetConnection.prepareStatement(MonetConnection.java:901) at nl.cwi.monetdb.jdbc.MonetConnection.prepareStatement(MonetConnection.java:825) at org.apache.commons.dbcp.DelegatingConnection.prepareStatement(DelegatingConnection.java:281) at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.prepareStatement(PoolingDataSource.java:313) (...) What do you recommend? Should I open a bug report? Ruben Silva

2 3

Monetdb ODBC datatype conversion problem
by baraa Mohamad 06 Nov '13

06 Nov '13

Dear MonetDB users, I have created a database link from oracle to monetdb using Monetdb ODBC driver, the link works fine but i have a strange results 😓 I have the following configurations: host1: Oracle (ubuntu 64bit)host2: MonetDB (ubntu 64bit)ODBC driver: MonetDB odbc (64bit) using unixODBC driver manager on monetdb i have the following table: emp (id integer , name varchar); test query: select id from emp where id<20; when I execute this query directly on montdb I get the following results (IDs from 1 to 19)ID123..19 BUT when I execute this query from oracle using dblink select "id" from "emp"@monetdb where "id"<20 ; I GET THE FOLLOWING RESULTS: ID-------- 18589934592 21.2885E+10 31.7180E+10 42.1475E+10 52.5770E+10 63.0065E+10 73.4360E+10 83.8655E+10 94.2950E+10 10 I cannot figure out the cause of the problem and how I can solve it (it seems a problem related to datatype conversion using ODBC) Could you please tell me what I should do.... Best regards,Baraa

3 6

Modify column datataype
by baraa Mohamad 06 Nov '13

06 Nov '13

Hello, I would like to know if it is possible to change a column type. I have a table with millions of records and I wand to change the type of the column (id) but I couldn't find how to do that. Thanks in advance for your help, Regards,Baraa

3 3

Database corruption
by Pedro Salgueiro 04 Nov '13

04 Nov '13

Hi, We are using MonetDB combined with Mondrian for a while ago, and ever since we started put more load on it, with several users using the same instance, we are experiencing some serious data corruption with no reason, leading lost data of some tables and some times loosing the entire database. This weekend we had such an issue, for no apparent reason, the data got corrupted and apparently all data of a table got lost. We have no way of seeing what was being done before the data got corrupted, but since we were not loading data into it, the only queries that could be running were queries generated from Mondrian. In the logs, the only thing that we can find related to this issue is the following: 2013-11-04 11:17:56 MSG merovingian[22802]: database 'normal' (16384) was > killed by signal SIGSEGV which, results in a "connection terminated" After alot of debugging, we found out that issuing a simple query as "select count(*) from table" would cause this issue: sql>select count(*) FROM table; > Connection terminated Under the sql_logs in the database directory, there is a file named "log" with the following contents: 052001 9516 and a file named "log.9516" which is empty. When I do "\d table", I get the following result. It seems the table lost all its columns: sql>\d "table" > CREATE TABLE "sys"."table" ( > ); It's also important to note that this only happened only some tables. The rest of tables are ok. Don't know if it's important, the entire database uses about 390MB, so it's quite small. This seems to be quite a big issue leading to data loss, and worst, corrupted databases preventing its usage, unless the entire database is rebuilt. I have some questions regarding this issue which I never saw them answered, and might be very useful to any users of MonetDB: In a situation like this, is there any way to understand what happened to MonetDB in order to avoid such situation in the future? What are the "sql_logs" for? I see there are some files there, but can't find any meaning of the contents. Could these files be used to recover lost data? In previous mails to the mailing list Martin stated that the system logs all entries added to each table. Where are these logs located? Also, could they be used to recover lost data? If you want, we can provide the entire database so you can debug and try to understand what happened in order to prevent such situations in the future. Best regards, Pedro Salgueiro

1 0

Login Help
by Nitin Gautam 04 Nov '13

04 Nov '13

Hi I need to exectue some batch jobs on Monet which are supposed to run as cron jobs. Since the process runs in background I was hoping to use mclient to execute the queries. But when I use mclient I am prompted to enter a password. I could not see any option to specify the password too as an argument to mclient. Is there something I am missing or is there another way to do what I am trying to do i.e. not use mclient. Thanks Nitin

2 2

Char limitation for ruby-monetdb-sql
by Christian Kleinke 01 Nov '13

01 Nov '13

Hi, I have problem regarding executing a script with ruby-monetdb-sql. The connection works and simple statements are executed as expected. However, when I try to send a large script, nearly 20000 characters, nothing happens. Neither an exception is thrown nor a SQL error is produced by MonetDB. However, I use "\<" with the same 20000 character script, it works as expected. Two questions: 1. Is there a char limitation for ruby-monetdb-sql? 2. Is there a MonetDB-SQL command to load scripts, something like sql>load("my_script.sql")? Thank you very much in advance. Christian

2 1

MonetDB using all availaible disk space
by Ruben Silva 01 Nov '13

01 Nov '13

Hello, I'm performing some bulk inserts into some tables (COPY INTO). Meanwhile some JOINs between those tables are executed and also some DELETEs. During this JOIN's, the disk begins to fill up and only stops after there is no more space available (60GB in my case). Same for RAM. After a (long) while the space gets freed up. The COPY INTO's are done without any significant delay. The files that use that space are some .tail and .head in the database bat folder. If the queries are not concurrent there aren't any problems. The JOIN it's not using any PK or FK. Have some one noticed this before? Should I open a bug report? Ruben Silva * *

2 2