November 2012 - users-list

[MonetDB-users] Books CDs
by CHARTS LICENSING 11 Aug '24

11 Aug '24

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[MonetDB-users] XQuery API and XLink/XUpdate support
by Alexandra Mart�nez 27 Jun '24

27 Jun '24

Hello all, I was wondering if there is any documentation about the API for XQuery (i.e., how to write xqueries from a Java program). Also, I am interested in using some features of XLink and XUpdate on top of my XML database. Is support for any of these in progress? Thanks in advance, Alexandra ______________________________________________________ Click here to donate to the Hurricane Katrina relief effort. http://store.yahoo.com/redcross-donate3/

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[MonetDB-users] Proofreading your professional documents
by Richard Hounslow 24 Feb '24

24 Feb '24

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INET query/type conversion issues
by Percy Wegmann 04 Dec '12

04 Dec '12

Hi MonetDB Team, I encountered a strange problem related to querying against an INET column. To reproduce: percy@percy-sandbox:~$ uname -a Linux percy-sandbox 3.2.0-33-generic #52-*Ubuntu* SMP Thu Oct 18 16:29:15 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux percy@percy-sandbox:~$ mclient -u monetdb -d click password: Welcome to mclient, the MonetDB/SQL interactive terminal (Oct2012) Database: *MonetDB v11.13.3 (Oct2012)*, 'mapi:monetdb://percy-sandbox:50000/click' Type \q to quit, \? for a list of available commands auto commit mode: on sql>create table test_table(col inet); operation successful (27.394ms) sql>insert into test_table values(*'127.0.0.1'*); 1 affected row (20.370ms) sql>insert into test_table values(*inet '127.0.0.1'*); 1 affected row (19.654ms) sql>insert into test_table values(*cast('127.0.0.1' as inet)*); 1 affected row (25.038ms) sql>select count(*) from test_table where col = '127.0.0.1'; +------+ | L1 | +======+ | *3* | +------+ 1 tuple (1.547ms) sql>select count(*) from test_table where col = inet '127.0.0.1'; +------+ | L1 | +======+ | *0* | +------+ 1 tuple (0.946ms) sql>select count(*) from test_table where col = cast('127.0.0.1' as inet); +------+ | L1 | +======+ | *2* | +------+ 1 tuple (0.982ms) sql>select count(*) from test_table where col = inet '127.0.0.1'; +------+ | L1 | +======+ | *2* | +------+ 1 tuple (0.937ms) sql>select count(*) from test_table where col = inet '127.0.0.1'; +------+ | L1 | +======+ | *0* | +------+ 1 tuple (0.801ms) Expected Result: All queries return a count of 3 Actual Result: Queries return different counts depending on how INET value was bound to query. Particularly interesting is that the output when using the inet '127.0.0.1' syntax is non-deterministic. Does this ring any bells? Should I log it? Cheers, -- Percy Wegmann +1 512 637 8500 ext 148 _______________________________________________ users-list mailing list users-list(a)monetdb.org http://mail.monetdb.org/mailman/listinfo/users-list

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Re: Same SQL Statement with different throughput time.
by Stefan Manegold 30 Nov '12

30 Nov '12

I guess it's a good idea to run your query in both cases, slow & fast prefixed with TRACE to see where time is spent. BTW, are we talking about genuine MonetDB (as Letters asked: which version) and hence original MonetDB SUM()-implementation, or has the code been modified or extended; f the latter: where & how? S. -- | Stefan.Manegold @ CWI.nl | DB Architectures (INS1) | | http://CWI.nl/~manegold/ | Science Park 123 (L321) | | Tel.: +31 (0)20 592-4212 | 1098 XG Amsterdam (NL) | ----- Reply message ----- From: "Lefteris" <lsidir(a)gmail.com> To: "Communication channel for MonetDB users" <users-list(a)monetdb.org> Subject: Same SQL Statement with different throughput time. Date: Fri, Nov 30, 2012 12:58 just restarting monetdb wont do it (OS will still keep in memory the data), you will also need to clean the memory, for example alloc all memory space, write 1's and then free again the memory. Swapnil, which version of monetdb are you using? IMO, 11 seconds vs. 30 milliseconds is too much of a difference to be just I/O. But maybe I am wrong, maybe your dbfarm is on a network? On Fri, Nov 30, 2012 at 12:42 PM, Charalampos Nikolaou <charnik(a)di.uoa.gr>wrote: > I think the reason is that for the first query the time is spent > mainly for loading your table in main memory. > Then, the second query has only the overhead of computing the sum over > column V1. > > To see this, you can run the query, restart monetdbd, and then run the > query again. You should get similar performance to that of the first > run. > > Babis > > On Fri, Nov 30, 2012 at 1:29 PM, swapnil joshi > <webmaster.swapnil(a)gmail.com> wrote: > > Hi Stefan, > > If monetdb doesn't maintain any caching then when i am creating > test1 > > database > > which contain demo table which contain 100 million records. > > > > When first time i am executing "SELECT SUM(V1) FROM DEMO;" > > monetdb gives me result in (11.4s) > > when immediate i am trying to execute same query "SELECT SUM(V1) FROM > DEMO;" > > It gives me result in (31.065ms) > > > > How / why this happen? > > > > I have also checked my OS memory cache and I have erased OS Memory cache. > > Now, I am trying same query "SELECT SUM(V1) FROM DEMO;" > > now also he take same time in milliseconds approximate(30.723ms) > > > > why he first time take lot of time and every next time he take negligible > > time. > > > > I hope you will clear my problem related of throughput time. > > > > -- > > Regards, > > Swapnil K. Joshi > > > > > > _______________________________________________ > > users-list mailing list > > users-list(a)monetdb.org > > http://mail.monetdb.org/mailman/listinfo/users-list > > > _______________________________________________ > users-list mailing list > users-list(a)monetdb.org > http://mail.monetdb.org/mailman/listinfo/users-list > _______________________________________________ users-list mailing list users-list(a)monetdb.org http://mail.monetdb.org/mailman/listinfo/users-list

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Same SQL Statement with different throughput time.
by swapnil joshi 30 Nov '12

30 Nov '12

Hi Stefan, If monetdb doesn't maintain any caching then when i am creating test1 database which contain demo table which contain 100 million records. When first time i am executing "SELECT SUM(V1) FROM DEMO;" monetdb gives me result in (11.4s) when immediate i am trying to execute same query "SELECT SUM(V1) FROM DEMO;" It gives me result in (31.065ms) How / why this happen? I have also checked my OS memory cache and I have erased OS Memory cache. Now, I am trying same query "SELECT SUM(V1) FROM DEMO;" now also he take same time in milliseconds approximate(30.723ms) why he first time take lot of time and every next time he take negligible time. I hope you will clear my problem related of throughput time. -- Regards, Swapnil K. Joshi _______________________________________________ users-list mailing list users-list(a)monetdb.org http://mail.monetdb.org/mailman/listinfo/users-list

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Monetdb Cacheing
by swapnil joshi 30 Nov '12

30 Nov '12

Hi, Is there monetdb maintain any SQL result cache. If yes, then How and where is it maintain? and If no then how he will get millions of rows result in millisecond. My System configuration is as follow : Hardware = Processor : Intel i7 2.3 GHz, RAM DDR3 8GB, HD 1 TB, OS = Ubuntu 12.04 I am new in IT world and i am doing some research on Monetdb. I have created my own user define function but it's result is not cached, every time it is doing operation on data and it take some in milli seconds. Please tell me about monetdb cacheing policy Can you give me some guide line? -- Regards, Swapnil K. Joshi _______________________________________________ users-list mailing list users-list(a)monetdb.org http://mail.monetdb.org/mailman/listinfo/users-list

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define your own user define function
by swapnil joshi 29 Nov '12

29 Nov '12

Hi, i am trying to define user define function which has argument integer bat and returning integer. step 1: i have added function defination in udf_80.sql as follow create function xtest(one integer) returns integer external name udf.xtest; step 2: i have added function defination in udf.mal module udf; command xtest(b:bat[:oid,:int]):int address UDFBATxtest comment "function xtest"; module batudf; command xtest(b:bat[:oid,:int]):int address UDFBATxtest comment "function xtest"; step 3: then i have define this function in udf.c file UDFBATxtest_(int *ret, BAT *src) { return MAL_SUCCEED; } str UDFBATxtest(int *ires, bat *ione) { BAT *bone = NULL; str msg = NULL; /* assert calling sanity */ assert(ione != NULL); /* bat-id -> BAT-descriptor */ if ((bone = BATdescriptor(*ione)) == NULL) throw(MAL, "batudf.xtest", RUNTIME_OBJECT_MISSING); /* do the work */ msg = UDFBATxtest_ ( ires, bone); return msg; } step 4: then i have compiled source code and installed it: step 5: i am try to execute xtest function on mclient but i got following error sql>select xtest(id) from student; TypeException:user.s23_1[16]:'udf.xtest' undefined in: _53:any := udf.xtest(_51:int) TypeException:user.s23_1[17]:'bat.insert' undefined in: _54:any := bat.insert(_45:bat[:oid,:int], _50:oid, _53:any) program contains errors step 6: write a mail and sent to you for getting help i hope you will give me. -- Regards, Swapnil K. Joshi _______________________________________________ users-list mailing list users-list(a)monetdb.org http://mail.monetdb.org/mailman/listinfo/users-list

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UDF aggregate?
by Miguel Ping 28 Nov '12

28 Nov '12

Greetings, We're currently evaluating MonetDB for a analytical DW and so far we are happy with the results. I am trying to implement a grouping function that calculates a a value over a set of strings, so that my queries would read like this: select metric, *udf_aggregate*(string_column) from table group by metric; for a bit of background, we're using a dinstinct value sketch called HyperLogLog http://metamarkets.com/2012/fast-cheap-and-98-right-cardinality-estimation-… http://blog.aggregateknowledge.com/2012/10/25/sketch-of-the-day-hyperloglog… and we're currently storing estimations for each time period (day). HLL lets you merge/aggregate a set of estimations (each estimation is a vector of numbers, we're currently storing it as a string) for an arbitrary range, and still have an accurate estimation. (I'm sure the literature doesn't call it estimations, sorry for my English) what I would like is a custom UDF like the one provided in MonetDB src (*reverse*)**but that would operate and behave like an aggregate function. Right now, I'm not considering using it for types other than /string/ (no need for polymorphic right now). Is this possible with an UDF? I found a way of registering aggregate functions on the mailing list, but the HLL is complex enough to warrant its own C impl, instead of a MAL function. Thanks, Miguel _______________________________________________ users-list mailing list users-list(a)monetdb.org http://mail.monetdb.org/mailman/listinfo/users-list

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Solid state drives for MonetDB
by Siddhartha Bagaria 28 Nov '12

28 Nov '12

Hello everyone! This is my second posting to this list and identical to the first because I am not sure if I was subscribed at the time. Please ignore if you have read this before. My apologies if this has been discussed elsewhere but a google search did not give me much. Let me give you a bit of background. We are planning to use a star schema in MonetDB as the backend for Pentaho BI reporting engine. We have a total of 2.4 B rows in the fact table and a maximum of 10 M rows in the dimension table. As you can see, this will be a read only database once the initial load is done. I was wondering what hardware architecture will give a reasonable performance over traditional BI queries. Let's define reasonable here by less than 1 minute turn-around time on joins between the fact table and the dimension table. On that note, what will be the expected performance on a machine with specs identical to the Amazon High I/O instance type which has two solid state drives - http://aws.amazon.com/ec2/instance-types/. I will of course combine the two drives in a software raid-0 configuration. My broader question is that columnar databases are typically optimized for hard drives to utilize the maximum possible disk transfer rate,; what advantages can a solid state drive offer over a traditional hard drive when used solely for MonetDB? I can imagine some advantages maybe in the swap-ins for VM pages but I am not really an expert. Also, some advantages in multi-threaded disk reads. Sid _______________________________________________ users-list mailing list users-list(a)monetdb.org http://mail.monetdb.org/mailman/listinfo/users-list

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