October 2013 - users-list

Monetdb python error in connection
by Rose Beck 19 Oct '13

19 Oct '13

I am using python-monetdb 11.16.0.7. I created my database farm and database according to instructions given below (source: http://www.monetdb.org/Documentation/monetdbd) % monetdbd start /home/my-dbfarm % monetdb create my-first-db Then I tried to connect to the database using the below mentioned command in python(https://pypi.python.org/pypi/python-monetdb/). Upon doing so I am getting the below mentioned error: >import monetdb.sql >connection=monetdb.sql.connect(username="monetdb",password="monetdb",hostname="localhost",database="my-first-db"); File "/usr/local/lib/python2.7/dist-packages/monetdb/sql/__init__.py", line 28, in connect return Connection(*args, **kwargs) File "/usr/local/lib/python2.7/dist-packages/monetdb/sql/connections.py", line 58, in __init__ unix_socket=unix_socket) File "/usr/local/lib/python2.7/dist-packages/monetdb/mapi.py", line 93, in connect self.socket.connect((hostname, port)) File "/usr/lib/python2.7/socket.py", line 224, in meth return getattr(self._sock,name)(*args) socket.error: [Errno 111] Connection refused Can someone please help me with this? Also my my-first-db resides inside my db-farm? I am not getting as to what should I do?

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Re: nulls last
by Klaudiusz 18 Oct '13

18 Oct '13

On 18.10.2013 12:05, Hilario Fernandes wrote: > O made the same test in SP4 and the results were the same, sum(null) kept > returning 0 and no results for the case. My tests in SP5 were done with a > clean database with no data imported, so according to your tests i should > at least have the correct value for the sum... > > These are the queries i've done and what i believe would be the expected > results: > > create table test (number int, name varchar(50)); > > insert into test values(1,'jonh'); > insert into test values(2,'mike'); > insert into test values(3,'mary'); > insert into test values(null,'austin'); > insert into test values(null,'jonh'); > insert into test values(null,'mary'); > > select name, sum(number) > from test > group by name; > > Result: > austin | 0 > jonh | 1 > mary | 3 > mike | 2 > > Expected: > austin | null > jonh | 1 > mary | 3 > mike | 2 > Hi Hilario, I've tested your query using default branch (11.16.0) and I can confirm that this bug also exist. So probably it depends on type of value by which you group. Probably if you try my example from http://bugs.monetdb.org/show_bug.cgi?id=3388 on fresh database, results should be as expected. So group by int works, but group by varchar doesn't :-(. I'm not sure if this is another bug than 3388 or it is the same. It's rather another one. Klaudiusz

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nulls last
by Hilario Fernandes 18 Oct '13

18 Oct '13

Hello, I'm trying to build a query with order by that puts nulls last always. I tryed to use the "NULLS LAST" expression but apparently it's not supported by monetdb. So i came up with something like this: select name, sum(number) from test group by name order by case when sum(number) is null then 1 else 0 end, sum(number) ASC Thing is, this works when the ordering column (number) is not aggretated, as soon as i throw the sum in there it returns no results. The sum of null values seems to be returning 0, is it possible to change that behaviour trough configuration? Is there a better way to achieve this? thanks

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Announcement: New Feb2013-SP5 Bugfix release of MonetDB suite
by Hannes Mühleisen 16 Oct '13

16 Oct '13

The MonetDB team at CWI/MonetDB BV is pleased to announce the Feb2013-SP5 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/>. Feb 2013-SP5 bugfix release Client Package * ODBC: Implemented retrieving variable-length data in parts with SQLGetData. See bug 3381. MonetDB Common * Removed the heap cache. Since the fix for bug 3323 which made that the cache was actually getting used, bug 3376 made clear that it didn't work very well. In addition, on Linux at least, the heap cache slows things down. Java Module * Rearranged order of returned columns of certain metadata functions to comply with the JDBC documentation. See bug 3356. Bug Fixes * 3323: Heapcache bugs/performance issues * 3331: SAMPLE will return same result every time. * 3356: DatabaseMetaData.getColumns() doesn't work correctly when using index-based getters * 3367: Fully qualified order by column gives "relational query without result" * 3368: BAT sortedness info ignored on ORDER BY and TOPN * 3370: SQL environment settings are updated even when the set statement fails * 3373: Setting table to read-only (Bug 3362) fails on big-endian * 3375: LIKE join: BATfetchjoin does not hit always * 3376: COPY INTO fails with HEAPextend: failed to extend: MT_mremap() failed * 3377: Query interfering with next query in same transaction, after SP4 * 3380: Python DBAPI driver throws exception when fetching EXPLAIN results * 3381: Windows ODBC driver hangs or crashes on simple queries

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Fwd: Query execution time
by baraa Mohamad 13 Oct '13

13 Oct '13

>> Hello dear MontDB users, >> >> I have a question please, I just need to get the query execution time >> without showing the results of the query (for performance comparaison) . >> Something which corresponds to the "traceonly" in Oracle. that will be >> greate if I can see the query plan but for the moment the most important >> for me is to get the query execution time. >> >> for example: I want to know the query exection time of this query >> (select * from source where a>10) knowing that I have more than one >> hundred million records which correspond to this predicate. >> >> Thank in advace for your appreciated help. >> >> Baraa

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Re: How to transfer monetdb database to another machine
by Rose Beck 13 Oct '13

13 Oct '13

Thanks a lot for helping. I am unable to figure as to where does * <dbfarm>/<dbname>* directory reside within ubuntu 12.04. Can you please help me with this. On Sun, Oct 13, 2013 at 6:06 PM, <users-list-request(a)monetdb.org> wrote: > Send users-list mailing list submissions to > users-list(a)monetdb.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.monetdb.org/mailman/listinfo/users-list > or, via email, send a message with subject or body 'help' to > users-list-request(a)monetdb.org > > You can reach the person managing the list at > users-list-owner(a)monetdb.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of users-list digest..." > > > Today's Topics: > > 1. Re: Query execution time (baraa Mohamad) > 2. Re: Query execution time (Martin Kersten) > 3. Re: How to transfer monetdb database to another machine > (Martin Kersten) > 4. Re: Query execution time (Martin Kersten) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 13 Oct 2013 12:31:35 +0200 > From: baraa Mohamad <bem85(a)hotmail.com> > To: Communication channel for MonetDB users <users-list(a)monetdb.org> > Cc: Communication channel for MonetDB users <users-list(a)monetdb.org> > Subject: Re: Query execution time > Message-ID: <BAY406-EAS1557A9804AABD08B94A7905A8190(a)phx.gbl> > Content-Type: text/plain; charset="utf-8" > > That's great! Thank you very much for your appreciated help. > > I just could't really understand the output of this command. > > This is my output: > Real: 1m23 > User: 0m24s > Sys: 0m2.3s > > I'm a little bit confused because when I execute the same query directly > without the time option i get 733,28ms. > > So i couldn't know what is the real execution time. > > > > > Le 13 oct. 2013 ? 11:29, "Martin Kersten" <Martin.Kersten(a)cwi.nl> a > ?crit : > > > > How about (time mclient -d db <inputfile >/dev/null) > > > >> On 10/13/13 11:24 AM, baraa Mohamad wrote: > >> Thank you for your answer. > >> But in general I would like to know how to get the query exexution time > >> without printing the results. It's for performance comparaison. I want > >> to evaluate MonetDB for my research and i'm working with large tables. > >> > >> Please any idea?? > >> > >> Greetings, > >> Baraa > >> > >> > >> > >> > >> Le 13 oct. 2013 ? 11:02, "Martin Kersten" <Martin.Kersten(a)cwi.nl > >> <mailto:Martin.Kersten@cwi.nl>> a ?crit : > >> > >>> Hi > >>> > >>> > >>>> On 10/13/13 10:55 AM, baraa Mohamad wrote: > >>>> > >>>>>> Hello dear MontDB users, > >>>>>> > >>>>>> I have a question please, I just need to get the query execution > time > >>>>>> without showing the results of the query (for performance > >>>>>> comparaison) . > >>>>>> Something which corresponds to the "traceonly" in Oracle. that will > be > >>>>>> greate if I can see the query plan but for the moment the most > >>>>>> important > >>>>>> for me is to get the query execution time. > >>>>>> > >>>>>> for example: I want to know the query exection time of this query > >>>>>> (select * from source where a>10) knowing that I have more than one > >>> This is not the ind of query you fire when you expect a large outcome. > >>> Better use SELECT COUNT(*).... > >>> > >>>>>> hundred million records which correspond to this predicate. > >>>>>> > >>>>>> Thank in advace for your appreciated help. > >>>>>> > >>>>>> Baraa > >>>> _______________________________________________ > >>>> users-list mailing list > >>>> users-list(a)monetdb.org <mailto:users-list@monetdb.org> > >>>> https://www.monetdb.org/mailman/listinfo/users-list > >>> _______________________________________________ > >>> users-list mailing list > >>> users-list(a)monetdb.org <mailto:users-list@monetdb.org> > >>> https://www.monetdb.org/mailman/listinfo/users-list > >> > >> > >> _______________________________________________ > >> users-list mailing list > >> users-list(a)monetdb.org > >> https://www.monetdb.org/mailman/listinfo/users-list > > _______________________________________________ > > users-list mailing list > > users-list(a)monetdb.org > > https://www.monetdb.org/mailman/listinfo/users-list >

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How to transfer monetdb database to another machine
by Rose Beck 13 Oct '13

13 Oct '13

I created monetdb database using the python library https://pypi.python.org/pypi/python-monetdb/11.16.0.7 on my ubuntu 12.04 lts server. Now I want to transfer this database to another ubuntu 12.04 lts server. However, I am unable to understand as to where(directory name) does monetdb create its database (within ubuntu 12.04) and what is the procedure which I must follow to transfer this database to another machine (so that i may query the database on another machine)?

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Crashed DB - BBPextend: trying to extend BAT pool beyond the limit
by Pedro Salgueiro 08 Oct '13

08 Oct '13

Hi, We have a MonetDB instance which was working without problems and suddenly stopped working. The following error shows up in "merovingian.log" when the client(mclient) tries to connect to the database: 2013-10-07 10:35:27 ERR testbd[12111]: !FATAL: BBPextend: trying to extend > BAT pool beyond the limit (16384000) > 2013-10-07 10:35:27 ERR testbd[12111]: > 2013-10-07 10:35:27 MSG merovingian[12015]: database 'testbd' (12111) has > exited with exit status 1 > 2013-10-07 10:35:27 ERR merovingian[12015]: client error: database > 'testbd' has crashed after starting, manual intervention needed, check > monetdbd's logfile for details > 2013-10-07 10:35:27 MSG merovingian[12015]: database 'testbd' has crashed > after start on 2013-10-02 16:36:06, attempting restart, up min/avg/max: > 0s/0s/0s, crash average: 1.00 1.00 0.83 (25-0=25) The DB size is about 1.1 GB. I really don't know how many tables, columns or records this specific database has, as it was being used for a while and the data is created/uploaded daily by its users. I tried with Feb2013-SP2, Feb2013-SP3 and Feb2013-SP4 I have a few question about this issue: 1 - Is there any way to see a more detailed log about the error? 2 - Is it possible to recover the DB from this error? I saw somewhere in the mailing list that removing the sql_logs could help starting the DB, at the cost of loosing some data. Already tried that with no success. 3 - What is this "BAT pool limit" thing? Is this related in some way with the number of tables, number of columns per table, or total amount of columns that a DB can have? Thank you, Pedro Salgueiro

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ORDER BY in sub-query
by Hadley Wickham 08 Oct '13

08 Oct '13

Currently, monetdb fails on this query: SELECT * FROM (SELECT * FROM "Batting" ORDER BY "playerID") with syntax error, unexpected ORDER, expecting INTERSECT or EXCEPT or UNION or ')' in: "select * from (select * (obviously that query isn't very useful, but it makes it harder to automatically generate sql) In case it matters, that query (with minor escaping variations) works in sqlite, postgres and mysql. Hadley -- Chief Scientist, RStudio http://had.co.nz/

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Create database other then "demo" in windows 8
by Prashant Patel 07 Oct '13

07 Oct '13

Hi all, I am using MonetDB on my windows 8 platform every time open monetdb client and server , it automatically connects to "demo" database by default. I am very new to these technology I have searched but couldn't find how to create our own database in monetdb (other then "demo"). Can anyone tell me how to create database and connect that database in monetdb server and client. I know this is very dump question but help will be really appreciated. ( If i can get some documents that would also work) Thanks in advance, Prashant Rajkotiya Research Aspirant

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