Thanks Darafei! > 9 сент. 2020 г., в 12:05, Darafei Komяpa Praliaskouski <m...@komzpa.net> > написал(а): > > > How does the 'sortsupport' routine interact with 'compress'/'decompress'? > > Which representation is passed to the comparator routine: the original > > value from the table, the compressed representation, or the decompressed > > representation? Do the comparetup_index_btree() and readtup_index() > > routines agree with that? > > Currently we pass compressed values, which seems not very good. > But there was a request from PostGIS maintainers to pass values before > decompression. > Darafei, please, correct me if I'm wrong. Also can you please provide link on > PostGIS B-tree sorting functions? > > We were expecting to reuse btree opclass for this thing. This way btree_gist > extension will become a lot thinner. :)
I think if we aim at reusing B-tree sort support functions we have to pass uncompressed values. They can be a lot bigger and slower in case of PostGIS. We will be sorting actual geometries instead of MBRs. In my view it's better to implement GiST-specific sort support in btree_gist, rather than trying to reuse existing sort supports. Best regards, Andrey Borodin.
