October 2015 - users-list

Problems implementing java jdbc
by Federico G Agripa 09 Oct '15

09 Oct '15

Hi, i'm having some issues implementing the java jdbc with a grails-app. Grails is a framework that runs on the jvm, allowing you to write all your code in java if you want. I'm using exactly the code you provide on your web page but it isn't recognizing a proper driver to connect to monet at runtime. I also tried to search some repo that provides a plugin or extension that allows me to use but i get the same error (the only one i found was www.clojars.com/monetdb) is there any example of a driver implementation you can provide or any forum to forward this? Thanks in advice

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Grails integration
by Federico G Agripa 09 Oct '15

09 Oct '15

Hello, i'm working on a grails plugin to easily integrate with monetDB. So I would like to here what functionalities will be useful to you guys because I want it to be useful to all of you to. I'm implementing it from the monet jar 2.17 and I hope to have it up in grails plugins as soon as possible. Btw any collaboration will be really welcome Regards

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Regex support
by imad hajj chahine 08 Oct '15

08 Oct '15

Hi, Monetdb is using pcre library for regular expression support, and using this function we can allow SQL to use the regex library: CREATE FUNCTION "pcre_replace" (origin string, pat string, repl string,flags string) RETURNS string EXTERNAL NAME pcre."replace"; I want to use regex for date conversion to the format supported by monetdb (yyyy-MM-dd), I have the following format dd/MM/yyyy, and i am trying to run the following with no success: select pcre_replace('15/10/2015', '^(3[01]|[12][0-9]|0?[1-9])/(1[012]|0?[1-9])/([0-9]{4})$', '\\3-\\2-\\1', 'i') select pcre_replace('15/10/2015', '^(3[01]|[12][0-9]|0?[1-9])/(1[012]|0?[1-9])/([0-9]{4})$', '{3}-{2}-{1}', 'i') select pcre_replace('15/10/2015', '^(?<day>3[01]|[12][0-9]|0?[1-9])/(?<month>1[012]|0?[1-9])/(?<year>[0-9]{4})$', '\\k<year>-\\k<month>-\\k<day>', 'i') My question is, is backreference supported in the replacement string; if yes, whats is the right syntax to use to reference the detected groups, if no, is there a clever way then using substring? Thanks

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windows function
by imad hajj chahine 07 Oct '15

07 Oct '15

Hi, Since monetdb support window RANK functions, is it possible to extend the sql library to support also window aggregate function like SUM, AVG ... useful for running total and moving average. Any plan to support this in the near future or the implementation is easy to be done with user defined functions. Thanks.

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UUIDs in MonetDB
by Doug Service 01 Oct '15

01 Oct '15

The documentation at https://www.monetdb.org/Documentation/Manuals/SQLreference/UUItype indicates that a UUID type is supported in MonetDB and gives the example select uuid(); +--------------------------------------+ | uuid | +======================================+ | 65950c76-a2f6-4543-660a-b849cf5f2453 | +--------------------------------------+ which appears to output from mclient. When I try the same with mclient I receive auto commit mode: on sql>select uuid(); SELECT: no such operator 'uuid' mapi.h only shows support for the following types #define MAPI_AUTO 0 /* automatic type detection */#define MAPI_TINY 1#define MAPI_UTINY 2#define MAPI_SHORT 3#define MAPI_USHORT 4#define MAPI_INT 5#define MAPI_UINT 6#define MAPI_LONG 7#define MAPI_ULONG 8#define MAPI_LONGLONG 9#define MAPI_ULONGLONG 10#define MAPI_CHAR 11#define MAPI_VARCHAR 12#define MAPI_FLOAT 13#define MAPI_DOUBLE 14#define MAPI_DATE 15#define MAPI_TIME 16#define MAPI_DATETIME 17#define MAPI_NUMERIC 18 Is it possible to get MonetDB to generate UUIDs and how is the type supported in mapi. Thanks Doug Service

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R aggregation fails when input is exactly 200K tuples
by Roberto Cornacchia 01 Oct '15

01 Oct '15

Hi, I have a suspect failure at exactly 200K tuples in input. I declared a simple aggregate on two columns (here it doesn't aggregate, for simplicity, it just returns 42). START TRANSACTION; CREATE table test (customer int, d string, n int); INSERT INTO test VALUES(1,'2015-01-01', 100); INSERT INTO test VALUES(1, '2015-01-02', 100); INSERT INTO test VALUES(2, '2015-01-03', 100); INSERT INTO test VALUES(2, '2015-01-01', 100); INSERT INTO test VALUES(2, '2015-01-02', 100); CREATE AGGREGATE sow(d string, n int) RETURNS DOUBLE LANGUAGE R { # aggregation function is constant, not important here sow_aggr <- function(df) { 42.0 } df <- cbind(d,n) as.vector(by(df, aggr_group, sow_aggr)) }; select customer, sow(d,n) from test group by customer; ROLLBACK; +----------+--------------------------+ | customer | L1 | +==========+==========================+ | 1 | 42 | | 2 | 42 | +----------+--------------------------+ The result is what I had expected. That is true until table test is long 199999 tuples. When it's exactly 200000 tuples, I get: Error running R expression. Error message: Error in tapply(seq_len(200000L), list(INDICES = c(0, 1, 2, 3, 4, 5, 6, : arguments must have same length Calls: as.data.frame ... by.data.frame -> structure -> eval -> eval -> tapply I checked the vector aggr_group, and indeed it is not 200000 long, as it should be. Instead, it is just one longer than then number of distinct values for customer (the grouping column). Any thought? Roberto

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