- users-list - monetdb.org

Confusing if MonetDB RDF/SparQL is supported
by Aris Setyawan 27 Apr '15

27 Apr '15

Hi All, In the recent week, I monitoring the monet's development commit logs. >From that logs, I have found that "RDF support was removed". But in the next log, some features under RDF was added. I'm bit confused about this. What is the state of RDF support in MonetDB? Thanks, -Aris

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Parallel Query
by Luciano Sasso 25 Apr '15

25 Apr '15

Hi, 1- On a single server, the query is executed in parallel?, Common relational database also has this ability (SQL Server, PostgreSQL etc.)? 2- And in a cluster, the same query is distributed for cluster nodes , in MonetDB? Att, -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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How to create a user with administrator rights
by Puthick Hok 24 Apr '15

24 Apr '15

Hi, I wan to use "COPY INTO table from 'file'" SQL instruction with a user rather than monetdb. This user needs the administrator rights. So far I have done these using monetdb user as the login: CREATE USER "mdb_user" WITH PASSWORD '"password"' NAME 'Test db user' SCHEMA "sys"; CREATE ROLE "testdbadmin" WITH ADMIN CURRENT_USER; GRANT "testdbadmin" TO "mdb_user" WITH ADMIN OPTION; CREATE SCHEMA "testdb" AUTHORIZATION "mdb_user"; ALTER USER "mdb_user" SET SCHEMA "testdb"; I learnt this from MonetDB UserGuide tutorial and from MonetDB authorisation documentation. However, I still cannot use 'mdb_user' for COPY INTO from file command. What is missing? What does 'ADMIN OPTION' do? How to make 'mdb_user' have the same right as monetdb? At the moment, I'm using monetdb user directly. But, it would be a bit nicer to have a different username. I'm working on a web service connecting to 3 different databases: mysql, postgres and now monetdb. They have a common username for the database connection. If I keep using monetdb user, the commonality rule is broken. I have another to use 'mdb_user' via STDIN and piping, but exporting DOTMONETDBFILE as an environment variable to make mclient login with out asking for password is another complexity dimension. Making mdb_user to have administrator rights like monetdb is the best option for me if this is possible, and I hope this is possible. Regards, Puthick

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MonetDB Cluster
by Luciano Sasso 23 Apr '15

23 Apr '15

Hi, Cluster MonetDB is only partitioning or is replication, or all? Att, -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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Database Size
by Luciano Sasso 23 Apr '15

23 Apr '15

Hi, What is the largest (size in G) database that you have worked? on a single server or cluster. Att, -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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Server crash with DDL in transaction
by Pete Hollobon 23 Apr '15

23 Apr '15

Running this on Oct2014-SP2 crashes the server. CREATE TABLE bugexample ( id INTEGER ); START TRANSACTION; ALTER TABLE bugexample ADD COLUMN newcolumn integer; ALTER TABLE bugexample ALTER COLUMN newcolumn SET NOT NULL; COMMIT; It is reproducible. I've logged a bug - number 3715. Thanks, Pete.

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Table types in MonetDB
by Robert Koch 22 Apr '15

22 Apr '15

Hi all, in the documentation of system catalog (https://www.monetdb.org/Documentation/SQLcatalog/TablesColumns) I found 4 types of tables: 0=Table/1=View/2=Generated/3=Merge What is 2 and 3? Thanks.

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Exactly 10 Seconds Delay during JDBC connect to MonetDB
by Robert Koch 22 Apr '15

22 Apr '15

Hi all, I'm using DBVisualizer to connect via JDBC to MonetDB. There is a delay of very exactly 10 seconds during the connection process. This only happens via JDBC. There are no DNS issues, since the connection is done via IP directly. Connection from the commandline of the server with mclient works perfectly. First step to get closer was to inspect the output of tcpdump. It seems to be on the side of MonetDB, since the last packet is the one sent to MonetDB (192.168.56.102) from my Windows Client (192.168.56.1). 09:33:24.663824 IP 192.168.56.1.57271 > 192.168.56.102.50000: Flags [.], ack 1, win 256, length 0 --- 10 soconds 09:33:34.676884 IP 192.168.56.102.50000 > 192.168.56.1.57271: Flags [P.], seq 1:3, ack 1, win 229, length 2 Additionally, DBVis ist connecting speedy with other databases (PostgreSQL) on the same server. Using following version: MonetDB 11.19.9 MonetDB Native Driver 2.14 (Liberica 20150123 based on MCL v1.11) I did not experience this problem in former versions of MonetDB. Any idea? Thank you.

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Creating an AWS AMI
by Maarten Sander 22 Apr '15

22 Apr '15

Hi everyone, Is there an easy way to create an AWS AMI running MonetDB? Perhaps someone maintains a Packer template? Regards, Maarten

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Strange syntax error when create trigger
by Caroptions Caroptions 21 Apr '15

21 Apr '15

Hi User-List, I am experiencing very strange behavior: CREATE TRIGGER marketdata.calc_sdate BEFORE INSERT ON marketdata.quotes FOR EACH ROW BEGIN ATOMIC -- select * from marketdata.quotes limit 1; END; ERROR: syntax error, unexpected '.', expecting WHILE in: "create trigger marketdata.calc_sdate before insert on marketdata." When I am creating trigger on table without schema it works fine. CREATE TRIGGER marketdata.calc_sdate BEFORE INSERT ON t1 ... Assuming t1 created without schema. All combination of " around schema and table, schema only, table only didn't help. Am I doing something wrong or this is the bug? Thanks,John

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More information about data loss in Bugzilla
by Luciano Sasso 20 Apr '15

20 Apr '15

I found this bug related to loss of data, is exactly what my bug, it was not clear in bugzilla if it was resolved or not, can tell me? I'm very insecure with MonetDB. https://www.monetdb.org/bugzilla/show_bug.cgi?id=3271 Att, -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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More information about data loss
by Luciano Sasso 20 Apr '15

20 Apr '15

Hi, Some more details about data loss in MonetDB, I saw all that yours have commented, and also is aware that I am not with the latest version (update in ), but is a serious mistake in the previous version . Have a comment that said a data synchronization correction was made, has to do with the change or reorganization of data, even when it is only run queries? Will by defragmentation reasons (vacum PostgreSQL), or index creation, the data is changed / moved and in this case can be lost. The query for example is "select product from products where cod_product in (123,12434,33434)", only the data in this column (cod_product) were lost (went blank), and still only clinhas related codes on in. The only thing out of the ordinary has happened is that the ongoing connection was aborted, Pentaho was killed forced, aborting the connections, but the MonetDB service has stopped "stop MonetDB dw", which usually stopped, when start "moentdb start dw", rose correctly without errors, but took a long time to rise, very much, and then went to see the lost data. Att, -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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MAL aggregate function difficulty
by Puthick Hok 20 Apr '15

20 Apr '15

Hi, I'm trying to define an aggregate function in MonetDB to concatenate rows in select group by (GROUP_CONCAT in MySQL). Postgres does not have this but there is an example to define this function. I'm starting to use monetdb from mysql thanks to MonetDB performance for large data sets. For some small tables, we have the feature to allow users to store small amount of custom data in rows and have a web service to convert rows into columns. We have this feature because we can do it in MySQL and Postgres using GROUP_CONCAT. I'm working on an open source breeding system which stores breeding data in MySQL, environment data in Postgres and now marker data in MonetDB in Australia. The system is called KDDart. Going back to my problem is that there is the same question with GROUP_CONCAT about 3 years ago. I have been googling and trying based on the information available for 2 days now. I have learnt how to define a MAL function and make it available in SQL mode by saving it in the autoload. However, when it comes to define and write a MAL aggregate function. I'm unable to find any step-by-step example. I could not start successfully with a simple aggregate solution. I google further that we a documentation on monetdb website about defining an aggregate function in R. I installed R and recompile my MonetDB source (MonetDB-11.19.9) on my openSuSe 12.2 with a pre-compiled R (R-base-2.15.1-1.1.4.x86_64). I followed the instruction to enable rintegration and compile successfully. R integration is loaded with mserver5 instruction. But when using monetdbd it says 'set: no such property: embedr'. I did bit of C debugging but I only got Segmentation fault. I don't know what you could do to help me out. I wish I could write the GROUP_CONCAT MAL function and being able to define it permanently in .mal file and being able to link it to the SQL. I hope you can help me out. Thanks in advance. Puthick

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MonetDB Cluster
by Luciano Sasso 17 Apr '15

17 Apr '15

Hello, I read all posts about cluster in MonetDB, but dont understand, I will make some specific quaestions, I think it will be more objective: 1- MonetDB makes automatic replication between nodes? 2- The writing is performed in a just node and this replicate to the other? 3. The reading can be done on any node? 4- There is a router that distributes queries between the nodes? 5- If a query from a client is very cost, this query can be distributed between nodes? 6- MonetDB makes sharding transparently? 7- How to funnel and multiplex ? Att, -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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MonetDB vs Vertica CE
by Luciano Sasso 17 Apr '15

17 Apr '15

Hi, The team of staff this questioning me about using Vertica, but it has limitations on the CE version. Someone already used the Vertica has some advantage over MonetDB? -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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MonetDB vs Vertica CE
by Luciano Sasso 17 Apr '15

17 Apr '15

Hi, thanks for awnsers. Precisely, I tried last year to deploy Vertical, but had trouble install and configure, since the MonetDB, was simply install and use, so do I use to this day with a database analytical about 30G, and 50 million records in the main table. I use Pentaho (Saiku) to explore the data, and also queries for creating dashboards. Now I pretty increase the volume of data, so that is posted another question about MonetDB clustered, it is the only thi still worries me, if I need to scalling. I dont think I still need something like HBase / Hadoop. Also have questioned me about using MongoDB, but from what I saw on MongoDB, needs a lot of programming to performance aggregations etc. with the MonetDB it is transparent. Today my data for analysis in MonetDB are fully denormalized not use model schema star. I see that many proposes the architecture with MongoDB for DW and Vertica or MonetDB, for analysis, but that think with volume that I have, I can use the MonetDB dw as well. I see there are many things about trying to force the use of Big data tools without really need it. Att, On 16/04/2015 10:38, 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: MonetDB vs Vertica CE (Ruben Silva) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 16 Apr 2015 14:37:47 +0100 > From: Ruben Silva <ruben.silva(a)cortex-intelligence.com> > To: Communication channel for MonetDB users <users-list(a)monetdb.org> > Subject: Re: MonetDB vs Vertica CE > Message-ID: > <CAER5Ptm+M8e1B5r0bgXKnMrADGhW+ch6Wcdy5co1jw8b=CehCA(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Hello Luciano, > > I don't have a full grasp of the new stuff introduced into MonetDB in the > last year, but as far as I know there are still major differences between > the two systems for me the most important is scalability. Vertica has no > single point of failure when working as a cluster. However the CE version > is limited to three nodes, so scalability is also limited in that case. > > Vertica relies heavily on projections as a way to improve performance. If > your data model is relatively stable it is something fairly easy to use, > but if your data model changes at a high rate you will have a considerable > amount of additional work managing the projections. Also if you use many > projections they will hurt your DML statements performance. > > MonetDB feeds on CPU and has no boundaries for its appetite, consuming as > much resources as possible in order to respond to a single statement. That > can be very good or very bad, it depends on your use case. Vertica has > resource pools that are used to regulate the stuff (IO, Ram, CPU) that each > query is allowed to use. > > I don't know your use case (and that is crucial for a good advice), but if > you are considering a scenario where you have a single machine for the > database system, then go with MonetDB without any doubt. It is just faster > and simpler. > > Cumprimentos (Regards), > > 2015-04-16 14:04 GMT+01:00 Luciano Sasso <luciano(a)gsgroup.com.br>: > >> Hi, >> >> The team of staff this questioning me about using Vertica, but it has >> limitations on >> the CE version. Someone already used the Vertica has some advantage over >> MonetDB? >> >> -- >> Luciano Sasso Vieira >> Data Scientist & Solutions Architect >> >> luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 >> 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br >> >> >> ------------------------------ >> [image: Avast logo] <http://www.avast.com/> >> >> Este email foi escaneado pelo Avast antiv?rus. >> www.avast.com >> >> >> _______________________________________________ >> users-list mailing list >> users-list(a)monetdb.org >> https://www.monetdb.org/mailman/listinfo/users-list >> >> >

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MonetDB clustered
by Luciano Sasso 16 Apr '15

16 Apr '15

Hi, I have a question about MonetDB clustered 1- It only replicates data between nodes? 2- He replicates data between nodes doing sharding? 3- When a query is sent to the cluster, it is processed by one node just or distributed by several nodes? 4- Cluster is related to multiplex-funnel? Att, -- Luciano Sasso Vieira Data Scientist & Solutions Architect luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br <http://www.gsgroup.com.br> --- Este email foi escaneado pelo Avast antivírus. http://www.avast.com

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Re: MonetDB vs Vertica CE
by Luciano Sasso 16 Apr '15

16 Apr '15

Hi, Right, but in the case when you take the data 30 minutes, you take all the data, and the bank have to see what should be changed or inserted? is not better you take only the new data in this way will always be inserted? I do it today Att, On 16/04/2015 10:47, 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: MonetDB vs Vertica CE (shamsul hassan) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 16 Apr 2015 14:47:46 +0100 > From: shamsul hassan <shamsulbuddy(a)gmail.com> > To: Communication channel for MonetDB users <users-list(a)monetdb.org> > Subject: Re: MonetDB vs Vertica CE > Message-ID: > <CAONo-du24VrQ_PR4nzNq7rT7Uw47fKQb5Pr376UWEDmTbCN7qQ(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > there is only one thing which has stopped me for using MonetDB in > production is the lack of UPSERT operation. > In my case new data comes every 30 mins and I cannot truncate and load the > whole table again. Ideally an UPSERT would have helped here as it will only > touch those records which are new or changed without truncating the whole > table. > > I raised the question few days before in Community list but didn't get any > useful answer. > > If i get any workaround for these UPSERTS the i would be as happy as pig in > dirty water :) > > Thanks > > > On Thu, Apr 16, 2015 at 2:37 PM, Ruben Silva < > ruben.silva(a)cortex-intelligence.com> wrote: > >> Hello Luciano, >> >> I don't have a full grasp of the new stuff introduced into MonetDB in the >> last year, but as far as I know there are still major differences between >> the two systems for me the most important is scalability. Vertica has no >> single point of failure when working as a cluster. However the CE version >> is limited to three nodes, so scalability is also limited in that case. >> >> Vertica relies heavily on projections as a way to improve performance. If >> your data model is relatively stable it is something fairly easy to use, >> but if your data model changes at a high rate you will have a considerable >> amount of additional work managing the projections. Also if you use many >> projections they will hurt your DML statements performance. >> >> MonetDB feeds on CPU and has no boundaries for its appetite, consuming as >> much resources as possible in order to respond to a single statement. That >> can be very good or very bad, it depends on your use case. Vertica has >> resource pools that are used to regulate the stuff (IO, Ram, CPU) that each >> query is allowed to use. >> >> I don't know your use case (and that is crucial for a good advice), but if >> you are considering a scenario where you have a single machine for the >> database system, then go with MonetDB without any doubt. It is just faster >> and simpler. >> >> Cumprimentos (Regards), >> >> 2015-04-16 14:04 GMT+01:00 Luciano Sasso <luciano(a)gsgroup.com.br>: >> >>> Hi, >>> >>> The team of staff this questioning me about using Vertica, but it has >>> limitations on >>> the CE version. Someone already used the Vertica has some advantage over >>> MonetDB? >>> >>> -- >>> Luciano Sasso Vieira >>> Data Scientist & Solutions Architect >>> >>> luciano(a)gsgroup.com.br <http://www.gsgroup.com.br> | tel: 17 >>> 3353-0833 | cel: 17 99706-9335 www.gsgroup.com.br >>> >>> >>> ------------------------------ >>> [image: Avast logo] <http://www.avast.com/> >>> >>> Este email foi escaneado pelo Avast antiv?rus. >>> www.avast.com >>> >>> >>> _______________________________________________ >>> 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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MonetDB with R Integration for Windows Issues
by Bogdan Dimitrov 15 Apr '15

15 Apr '15

Hello everyone, I have been trying to get Embedded R in MonetDB to run on Windows 7 and I ran into a bunch of problems. I was wondering if anybody else has been able to get it running or whether there are better workarounds for the issues that I found. I am using manually built MonetDB version 11.19.9 with R integration enabled. The problems I had to fix seem to stem from the fact that the MonetDB is built using the VS2010 compiler, while the R assemblies are built with the MinGW compiler, so sometimes the two do not play nicely together and the server crashes with access violation errors on several occasions. After some debugging of both MonetDB and R source I identified the following problems: 1. The call in rapi.c line 373: R_tryEvalSilent(VECTOR_ELT(R_ParseVector(mkString(rapiinclude), 1, &status, R_NilValue), 0), R_GlobalEnv, &evalErr); fails with an access violation error. The problem is that the path contained in the char array called rapiinclude uses backslashes (Windows style), while the R code expects a UNIX style path with forward slashes. I added a bit of code to rapi.c that replaces the backslashes with forward slashes in the path to work around this issue. 2. The call in rapi.c line 742: fprintf(stdout, "# MonetDB/R module loaded\n"); fails with an access violation (as well as the rest of fprintf calls in rapi.c). Passing file handles across dll boundaries can cause problems even when same compiler is used, here it is passed between dlls built with different compilers (VS2010 compiled lib_rapi.dll to MinGW compiled R.dll). I replaced all fprintf calls with printf to work around this issue. Fixing the above issues I managed to run MonetDB with embedded R on Windows 7 and all the R scripts I tried seemed to work fine until I tried to use an R library that had to be downloaded first automatically using the overloaded library() function as described in https://www.monetdb.org/content/embedded-r-monetdb . 3. The call in rapi.R line 32: install.packages(package,repos=c("http://cran.rstudio.com/"),lib=.rapi.libdir,quiet=T) causes access violation as well, but I have not been able to find a workaround for this yet (apart from manually downloading the R package and dropping it in rapi_packages folder in dbfarm, so no downloading needs to happen). These should be Windows specific issues as MonetDB and R can be compiled with the same compiler for *NIX systems, while the MonetDB build instructions for Windows explicitly state that there is no longer support for compilers other than Microsoft Visual Studio's. I would appreciate it if anybody can help me solve the problem with downloading R libraries or knows a way to get the R integration running on Windows without the custom code changes described above. Best regards, Bogdan Dimitrov ________________________________

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segfault in function when return table from IF (or any code branch)
by Caroptions Caroptions 14 Apr '15

14 Apr '15

DROP FUNCTION test(text); CREATE FUNCTION test(a text) RETURNS table(SOMEFIELD date) BEGIN IF a is NULL THEN return table( select cast(sdate as date) from quotes limit 10 ); ELSE return table( select cast(sdate as date) from quotes limit 10 ); END IF; END;-- ****** OR ******CREATE FUNCTION test(a text) RETURNS table(SOMEFIELD double) BEGIN declare table t(f double); select 0.0 into t; return t; END; -- ****** OR ******CREATE FUNCTION test(a text) RETURNS table(SOMEFIELD double) BEGIN declare table t(f double); set t = table (select 0.0); return t; END; When submit (not even execute) -> segfaultBug: https://www.monetdb.org/bugzilla/show_bug.cgi?id=3699Thanks,Vasili

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Time comparison is not correct
by Caroptions Caroptions 14 Apr '15

14 Apr '15

select cast(timestamptz '2001-01-01 19:00:00 -04:00' as timetz)< cast( timestamptz '2001-01-01 23:00:00 -04:00' as timetz); -> false. Bug: https://www.monetdb.org/bugzilla/show_bug.cgi?id=3700 As an idea (and it seems PostgreSQL uses this approach) when you convert to UTC, you should not "reset" count at 24 but allow hours more that 24:00. This way 23:00 -04:00 will become 27:00 UTC then the comparison will be correct regardless timezone. Thanks,John

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NThreads Parameter and the Performance Related to the Number of Database Instance
by Joseph Mate 10 Apr '15

10 Apr '15

Hello MonetDB Users, In short: 1) What does the nthreads setting mean? 2) Why does performance increase as you increase the number of database instances of a single farm? Is there any way to avoid this? In long: What does the nthreads setting mean? From the manpage[1] it's the number of worker threads that perform main processing. Is this the total number of threads for that database instance? Or is it per query? I've compared the performance of different settings. I find it strange that nthreads=8 would perform the best because I have 12 cores. I confirmed the number of cores by checking nproc. Here are my plots showing that 8 threads performs best on my system: Throughput: https://cs.uwaterloo.ca/~jmate/nthreads-and-database-instances/throughput-v… Average Response Ttime: https://cs.uwaterloo.ca/~jmate/nthreads-and-database-instances/rsptm-avg-vs… 99th Percentile Response Time: https://cs.uwaterloo.ca/~jmate/nthreads-and-database-instances/rsptm-p99-vs… The second thing is: why does the performance increase if I distribute the conncurent clients over multiple database instances on the same data farm? I expected the opposite; performance should decrease. I thought I would increase the overhead by adding more database instances to the same farm. Is there any way to avoid this? Below are the plots I have. I used 40 concurrent TPC-H clients for all: Throughput: https://cs.uwaterloo.ca/~jmate/nthreads-and-database-instances/throughput-v… Average Response Time: https://cs.uwaterloo.ca/~jmate/nthreads-and-database-instances/rsptm-avg-vs… 99th Percentile Response Time: https://cs.uwaterloo.ca/~jmate/nthreads-and-database-instances/rsptm-p99-vs… Context: To give you guys some context on my project: I'm a Master's student doing my research on DBaaS tenant placement. I am evaluating some placement algorithms by using the TPC-H workload and MonetDB as the database. I am using separate database instances on a single farm for isolation. The workload I'm testing with runs read only queries from the TPC-H benchmark. Each TPC-H client is a thread each with its own persistent connection to the database running the following pseudocode: while true for queryNum 1 ... 22 # except query 15 which creates a tmp table run queury queryNum Each database instance has 100MB of data. Thank you for your time, Joseph References: [1] https://www.monetdb.org/Documentation/monetdb-man-page

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first_value/last_value solution in MonetDB
by Caroptions Caroptions 10 Apr '15

10 Apr '15

Hi, Till I am trying to resolve my business problem I discovered the segfault bug which I have reported in MonetDB bug tracking system. I believe Monetdb is great product and team is moving in right direction utilizing latests advances in technology. Nevertheless my "business" problem is to build OHLC Time Series for longer time frame from shorter ohlc time series. I need partition by interval (5 minutes, 30 minutes, 1 hour, 1 day) and get first record of open, max of high, min of low and last of close from let's say 1 minute ohlc series. In postgresql there are 2 functions: first_value and last_value, which allows to do exactly this. Are there any function/approach/techniques which could be utilized to have the same results in MonetDB, I could do this aggregation on client side but this way I will not utilize DB potential and mainly the network traffic will be prohibitive for the solution. I am sure this question is already addressed somewhere, but I couldn't find, the solution should be trivial and pretty standard but I no luck on my side, if you push me in right directly I will really appreciate. Thank you in advance!John

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database was killed by signal SIGSEGV
by Miguel Costa 09 Apr '15

09 Apr '15

Hi there, I'm running a monetdb server with the 2014-SP2 version. I have 61GB of RAM with CentOS 6.5. I have one table with almost 100M rows. I do cycles of 85000 inserts and everything is fine for the first ones, but after some cycles it just gives the error "database was killed by signal SIGSEGV" On my var/log/messages gives the error : kernel: mserver5[6773]: segfault at 18 ip error 4 in lib_sql.so. In the beginning everything was fine, I manage to insert the 100M and I didn't had any problems, but now it's constantly crashing. My database size is more or less 40GB. The memory on the server occupied doesn't reach 1GB. Any suggestions of what to look for?

2 1

Querying a monetdb cluster
by José Raúl Pérez Rodríguez 09 Apr '15

09 Apr '15

Hi, I am new in monetdb. How do I make a query to a cluster? I maked a test inserting data into each particular node of a two node cluster, but I don't see the way of making queries to the cluster, I known that multiplex funnel can return data from several nodes, joining data obtained from each node, but with multiplex funnel, I can't sort the data. There is not doc that explains this problem?

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