Hi, Richa! On Mar 13, Richa Sehgal wrote: > Dear mentors, > > I am currently pursuing Master's in University of Illinois at Urbana > Champaign, USA and completed by B.Tech from Indian Institute of Technology > - Delhi (IIT- Delhi) > > This is regarding GSoC 2015. I am really interested in databases, and I was > very excited to see all these projects listed here. The exciting part was > that some of the projects are really “hard” as in they have challenged the > database community since a long time, and thus it would be very interesting > to solve some of these challenges as part of GSoC. > > I want to discuss 2 projects: > > A. Indexes on virtual columns > > Materialization gives us two things: > > 1. A name to the column which we can use in queries
Not quite. Even non-materialized columns always have names. See https://mariadb.com/kb/en/mariadb/virtual-computed-columns/ > 2. A formal "regular" column which is stored and indexed in the regular > fashion - Disadvantage: Extra memory requirements for the materialized > column. Exactly. > My initial thoughts on this project are the following: > > We do need the name of the column which can be used to query. So maybe we > can expose a command such as: > > create virtual_index <name> on <column_name> <expression> > > What this would do would run a regular query which evaluates expressions > (like in WHERE clause) and the feed the result into the indexer. This index > can then be stored in the regular fashion. Yes, in a sense. The update_virtual_fields() function calculates values of virtual columns (e.g. if one does SELECT * from table_with_virtual columns). In MyISAM, _mi_make_key() creates a key from the row image. Pure virtual columns are not in the row image, so they cannot be indexed that way. So, in a very simplified way, this project is about calling update_virtual_fields() from _mi_make_key(). > B. Having UDFs returning an array/set > > There are three approaches that I can think of: ... > I would like to discuss these and then decide on one of them. Am I > approaching this in the right direction? Can you please point me to > the next steps? I'm afraid, the project was badly formulated. I've rewritten it now to highlight what it is really about. It is not about arrays, the important part is a "result set". See MDEV-5199 Regards, Sergei _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
