2014-03-18 18:47 GMT+04:00 Robert Haas <robertmh...@gmail.com> > > > > If the fetch() is specified by the developer, then using it, algorithm > can > > retrieve the data directly to output areas at this stage, without > reference > > to the heap. > > This seems to be the crux of your proposal, but it seems vague: what > exactly do you mean by "retrieve the data directly to output areas"? > What data are you going to retrieve and where are you going to put it? >
I meant Datum that storages in Gist-tree nodes. Now gistgettuple() returns xs_ctup.t_self (item pointer). I'm going to add index-only scan functionality: gistsettuple() will return pointer and Datum itself as xs_itup . So queue will contain both the pointer and the Datum. If visibilitymap_test returns true then Datum from xs_itup would be added into queue. Otherwise page must be scanned. Another question to consider is: which operator classes do you > anticipate that this will work for and which ones do you anticipate > that it will not work for? Any operator class that lossifies that > input data before storing it in the index is presumably doomed, but > which ones do that, and which do not? > about amcanreturn: I'm going to create function gistcanreturn() = If fetch() is defined for all indexed columns? And last point of my project is to implement fetch() for existing opclasses based on GIST. -- Best regards, Lubennikova Anastasia
