Hi Daniil, Just to keep you updated I have created a ticket with some basic information in it (which we have already gone though) and updated the MariaDB KB 2017 page accordingly.
The ticket can be found here: https://jira.mariadb.org/browse/MCOL-641 Kind Regards Andrew On 20/03/17 22:52, Andrew Hutchings wrote: > Hi Daniil, > > Yes, it is currently stored as an int64. We want to extend it but also > some of the internal functionality converts it to a double (see > utils/funcexp/func_math.cpp for example). Every function would need to > be fully tested to make sure that it uses DECIMAL end-to-end and handles > overflow scenarios correctly. > > At the moment ColumnStore's integer storage can only handle fixed 1, 2, > 4 and 8 byte columns. 2, 4 and 8 are used for DECIMAL. It should be > somewhat easily extendible to 16 byte columns. I believe this will give > us the capability to store the same amount of digits as MariaDB. If at > CREATE TABLE it is determined that a DECIMAL will only require 8 bytes > it should only use an 8 byte column, if it needs bigger it should use a > 16 byte column. > > In addition the DDL code in ColumnStore will need modifying to handle > the range. > > The ability to have 16 byte columns will also help us at a later date > with other potential data types in the future too. > > Here is the first attempt at implementing 16byte columns in InfiniDB. > This work has not made its way into ColumnStore yet and there are likely > quite a few things this doesn't touch: > > https://github.com/infinidb/infinidb/commit/eb1e2df76bda95a43cd2948890bff98f8785a805 > > Kind Regards > Andrew > > On 20/03/17 21:57, Даниил Медведев wrote: >> I looked at the code (for better understanding of problem), and now I >> have some questions: >> Do I understand correctly, that now it is stored as an int64 value with >> a scale and we want to extend it, and store maximum 65 digits as in >> documentation? >> https://github.com/mariadb-corporation/mariadb-columnstore-engine/blob/master/dbcon/execplan/treenode.h#L62 >> >> We will use fixed size type or extandable? >> >> I think that I will find all answers of my questions in specification, >> and there is no point in asking more questions. >> >> Regards, >> Daniil Medvedev >> >> 2017-03-20 21:51 GMT+03:00 Andrew Hutchings <[email protected] >> <mailto:[email protected]>>: >> >> Hi Daniil, >> >> Many thanks for your interest. We haven't fully specified it yet (I'll >> build a full specification later this week). But I suspect the following >> would be involved: >> >> * Implementation of methods to handle MariaDB's DECIMAL format >> * Support for a longer than 8-byte numeric column type (there is an >> InfiniDB tree with work for this already) >> * Modification of the primitives processor for the math >> * Modification of the function expression processor to handle the >> new type >> * Version upgrade support for DECIMAL from the current form to the >> new form >> >> In the mean time please let me know if you have any questions. >> >> Kind Regards >> Andrew >> (Senior Software Engineer, MariaDB ColumnStore) >> >> On 19/03/17 23:09, Даниил Медведев wrote: >> > Hello, >> > >> > I took part in GSoC last year, and closed one of MariaDB tasks. Now I >> > want to continue programming with MariaDB developers and solve a >> new task. >> > I considered some of proposed tasks, and was interested in >> "ColumnStore: >> > Add full support for DECIMAL". >> > I think this task is doable in the given time and I might solve it. >> > >> > P.S. My github link: https://github.com/medvdanil >> > >> > Regards, >> > Daniil Medvedev >> > >> > >> > >> > _______________________________________________ >> > Mailing list: https://launchpad.net/~maria-developers >> <https://launchpad.net/~maria-developers> >> > Post to : [email protected] >> <mailto:[email protected]> >> > Unsubscribe : https://launchpad.net/~maria-developers >> <https://launchpad.net/~maria-developers> >> > More help : https://help.launchpad.net/ListHelp >> <https://help.launchpad.net/ListHelp> >> > >> >> -- >> Andrew Hutchings - LinuxJedi - http://www.linuxjedi.co.uk/ >> >> > -- Andrew Hutchings - LinuxJedi - http://www.linuxjedi.co.uk/ _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
