On Wed, Jul 08, 2009 at 06:42:30AM -0400, Peter Benjamin Volk wrote: > <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
HTML mail isn't a good idea... not as easy to read. > Multiple things. At first of course at column store oriented engines. > The problem with this is that the MySQL core is strongly row based and > would not take any column oriented optimizations into account even if > the engine is column oriented. So any column store would actually need > to bring their own optimizer and partially operators with them. The > Idea would be to have a curser on the table (as proposed by you) but > when scrolling over the data set to have two different access methods. > One column oriented and the other row oriented. With both of these > options it would be possible to access complete rows or have the SE it > self filter out the unnecessary columns. Maybe the access methods could > be controllable by the capabilities of the SE. This would give the > optimizer multiple possibilities to access the data on a row with > different costs. For column oriented stores it would be cheaper to read > over the column API and for row based it would read over the row API. > To compensate the different APIs you can define different > transformation operators. Also this way specific selections can be > pushed down to the SE very easily--SELECT a,b FROM t would only read > columns a and b from the table t. Instead of reading the complete row > of t (maybe consisting of N+1 columns). The performance degradation of > the API to NDB is possibly due to the fact that MySQL would read the > complete row from a column oriented interface (speculation only. Don't > know the work on this topic in NDB). There has been quite a bit of > publications on the SIGMOD '09 that column stores are very suitable for > analytics as well as OLTP. So maybe this might be an interesting trend? > Also having the different access methods modularizes the DBMS a lot > more --> more plugins :) wich is in the sense of Drizzle. <br> the read_set and write_set parameters should take care of the only retreiving/setting certain columns. Although that still leaves optimiser things... which is another project altogether :) -- Stewart Smith _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
