October 2015 - developers-list

MonetDB type system documentation
by Stefan Manegold 07 Oct '15

07 Oct '15

Dear all, since there is ever so often confusion about the (admittedly not entirely trivial) type system of MonetDB, and about which type to use for what to ensure correct semantics and portability, I felt free to collect some of the crucial information on the MonetDB wiki. Under https://www.monetdb.org/wiki/Main_Page following links "3.1 Software development" and then "MonetDB type system" gets you to https://www.monetdb.org/wiki/MonetDB_type_system I hope this helps to clarify some details. In particular mind the "Type Rules" given there (with any of your MonetDB-related code that you eventually want to see in some future MonetDB release). Your cooperation is highly appreciated! In case you have any questions about correct and proper type usage in MonetDB, please do not hesitate to ask Sjoerd or myself (preferably via the MonetDB developers mailing list, if not in person). Enjoy! Stefan -- | Stefan.Manegold(a)CWI.nl | DB Architectures (DA) | | www.CWI.nl/~manegold/ | Science Park 123 (L321) | | +31 (0)20 592-4212 | 1098 XG Amsterdam (NL) |

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Getting a column type for result column
by Dimitar Nedev 03 Oct '15

03 Oct '15

Dear co-developers, How does one get the type of a column given a 'res_col'. I mean a humanly readable one, in other words get the value that determines the type and how they map to data types. Cheers, Dimitar

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Server crash when trying convert timestamp to string with incorrect format
by Sherzod Mutalov 01 Oct '15

01 Oct '15

Hello Developers, MonetDB server crashes when trying to execute timestamp_to_str function with incorrect format string. SQL: SELECT timestamp_to_str(current_timestamp, '%Q'); I send bug report, https://www.monetdb.org/bugzilla/show_bug.cgi?id=3816 But, also I need QUARTER extraction from date values by SQL server, like "extract(quarter from date '2015-10-01')" = 4 Now, I am using this "((extract(month from {0}) - 1) / 3 + 1)" -- Best regards, Sherzod mailto:shmutalov@gmail.com

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Some annoying bugs with date and number operations
by Sherzod Mutalov 01 Oct '15

01 Oct '15

Hello Developers, Firstly, I must say thank you for releasing MonetDb Jul2015. Secondly, Problem 1: Following query crashes the mserver5: SELECT ~0; -- here can be any number or numeric column There is NULL dereference problem in rel_select.c file at line 3915 (rel_binop function). dl->next->next is null, but rel_value_exp receives dl->next->next->data.sym as argument. How correctly use bitwise NOT operator with SQL? Problem 2: Following queries produces incorrect results: SELECT ( (current_timestamp - str_to_timestamp('2015-09-30', '%Y-%m-%d'))/86400 , BIGINT); SELECT CONVERT( CONVERT( (current_timestamp - str_to_timestamp('2015-09-30', '%Y-%m-%d')) , BIGINT) /86400 , BIGINT); SELECT (current_timestamp - str_to_timestamp('2015-09-30', '%Y-%m-%d'))/86400.0; Server info: # MonetDB 5 server v11.21.5 "Jul2015" # Serving database 'demo', using 4 threads # Compiled for x86_64-pc-winnt/64bit with 64bit OIDs dynamically linked # Found 15.916 GiB available main-memory. -- Best regards, Sherzod mailto:shmutalov@gmail.com

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