> 9 сент. 2020 г., в 00:05, Heikki Linnakangas <hlinnaka@iki.fi> написал(а): > > I've been reviewing the patch today. The biggest changes I've made have been in restructuring the code in gistbuild.c for readability, but there are a bunch of smaller changes throughout. Attached is what I've got so far, squashed into one patch. Thanks!
> I'm continuing to review it, but a couple of questions so far: > > In the gistBuildCallback(), you're skipping the tuple if 'tupleIsAlive == false'. That seems fishy, surely we need to index recently-dead tuples, too. The normal index build path isn't skipping them either. That's an oversight. > > 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. :)
Base representation for index compressed datatype is GIDX, which is also a box. We can make it work on top of it instead of the original representation. There is no such thing as "decompressed representation" unfortunately as compression is lossy.
