July 2015 - developers-list

Re: Re: mserver5 crash while login with newly created user
by Sherzod Mutalov 14 Jul '15

14 Jul '15

> > > Adding users on the mal level isn't supported on the sql level. > > Ok, how can I create sql user on server side? Is there a way to obtain this?

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mserver5 crash while login with newly created user
by Sherzod Mutalov 14 Jul '15

14 Jul '15

I want to change default monetdb user password to other and create new database user when starting new database instance, before any client connects to newly created db. I starting server with follow command: mserver5.exe --dbinit="oldpwd := clients.backendsum(\"monetdb\"); newpwd := clients.backendsum(\"secret\"); clients.changePassword(oldpwd, newpwd); usrpwd:=clients.backendsum(\"secret2\");clients.addUser(\"newuser\", usrpwd);" --dbpath="D:\Projects\git\monetdb-latest-dev\NT\build\bin\dbfarm\demo" There are no errors. Then I trying to connect to this server: mclient.exe -u monetdb -P secret No errors, connected. Then, I am trying to open new session: mclient.exe -u newuser -P secret2 Ooops! Client exits with error: Connection terminated Server unexpectedly dies. I restarted server, then try connect one more time, same behaviour: "Connection terminated". Ok. Then I connected to server with default "monetdb" user and checked "users" table: mclient.exe -u monetdb -P secret sql>select * from users; +---------+---------------+----------------+ | name | fullname | default_schema | +=========+===============+================+ | monetdb | MonetDB Admin | 2000 | | newuser | null | null | +---------+---------------+----------------+ 2 tuples (5.332ms) Look, fullname and default_schema for "newuser" is null. I think "null pointer dereference" somewhere in code. If I creating user with SQL (CREATE USER ...) everything works fine, I can connect.

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mserver5 crash while login with newly created user
by Sherzod Mutalov 14 Jul '15

14 Jul '15

I tested with monetdb v11.19.13 and v11.19.15 (Windows 7 x64, MSVC2013)

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Hash join implementation
by Xu,Wenjian 11 Jul '15

11 Jul '15

Hi Stefan, Thank you very much for your suggestions. They are very helpful. I am also trying to understand the hashjoin() implementation in gdk/gdk_join.c. I am aware of the classical *multi-pass partitioned hash join* as described in the literature: [1] Main memory hash joins on multi-core CPUs: tuning to the underlying hardware. Cagri Balkesen et al. ICDE13 [2] Optimizing main-memory join on modern hardware. Stefan Manegold et al. TKDE (2002) I was trying to follow the idea in these papers to understand the implementation of hash join in MonetDB but failed. Do you have any suggestions? Are there any other papers/documents I can refer to? Thanks. Best regards, XU Wenjian >Hi Wenjian, >you might want to consider studying the logical (relational) >and physical (MAL) plans, or debug your SQL queries; for >details see >https://www.monetdb.org/Documentation/Manuals/SQLreference/Runtime >You might also want to consider using the MAL debugger >directly; cf., >https://www.monetdb.org/Documentation/Manuals/MonetDB/debugger >Also, a combination of mserver5's --trace and ->gdk_debug=2097152 ("ALGOMASK") >might be useful. >Best, >Stefan ----- On Jul 8, 2015, at 11:42 AM, Xu,Wenjian zeroxwj at gmail.com <https://www.monetdb.org/mailman/listinfo/developers-list> wrote: >>* Hi, *>> >>* My objective is to investigate that, given an SPJ query, how are BATs *>>* *physically* processed (changed) among relational algebra operators (e.g., *>>* select, join). I do not care about how query is translated into execution plan *>>* in MAL, what I care is the interaction of operators in the kernel (aka., gdk) . *>> >>* My current plan is to add some debug information in those operators (e.g., *>>* functions in src/gdk_join.c, src/gdk_select.c) and re-compile the system. Then, *>>* I will pose an SPJ query (through console) and check the system log to see how *>>* those operators are invoked in sequence. *>> >>* But this method seems inefficient and I would like to ask if there are any *>>* alternatives, for example, is it possible to debug the system *step-by-step* *>>* given an input query (or its logical query plan). *>> >>* Thank you very much for any kind help. *>> >>* Best regards, *>>* Wenjian *>> >> >*>*

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Interaction of operators in the kernel.
by Xu,Wenjian 08 Jul '15

08 Jul '15

Hi, My objective is to investigate that, given an SPJ query, how are BATs *physically* processed (changed) among relational algebra operators (e.g., select, join). I do not care about how query is translated into execution plan in MAL, what I care is the interaction of operators in the kernel (aka., gdk) . My current plan is to add some debug information in those operators (e.g., functions in src/gdk_join.c, src/gdk_select.c) and re-compile the system. Then, I will pose an SPJ query (through console) and check the system log to see how those operators are invoked in sequence. But this method seems inefficient and I would like to ask if there are any alternatives, for example, is it possible to debug the system *step-by-step* given an input query (or its logical query plan). Thank you very much for any kind help. Best regards, Wenjian

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