database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-03 20:02:46 +03:00
Code Activity

Allow GiST distance function to return merely a lower-bound.

Browse Source 
The distance function can now set *recheck = false, like index quals. The
executor will then re-check the ORDER BY expressions, and use a queue to
reorder the results on the fly.

This makes it possible to do kNN-searches on polygons and circles, which
don't store the exact value in the index, but just a bounding box.

Alexander Korotkov and me
This commit is contained in:
Heikki Linnakangas
2015-05-15 14:26:51 +03:00
parent ecd222e770
commit 35fcb1b3d0
19 changed files with 699 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
src/backend/access/gist/gistscan.c
View File

@ -85,6 +85,11 @@ gistbeginscan(PG_FUNCTION_ARGS)
/* workspaces with size dependent on numberOfOrderBys: */
so->distances = palloc(sizeof(double) * scan->numberOfOrderBys);
so->qual_ok = true; /* in case there are zero keys */
if (scan->numberOfOrderBys > 0)
{
scan->xs_orderbyvals = palloc(sizeof(Datum) * scan->numberOfOrderBys);
scan->xs_orderbynulls = palloc(sizeof(bool) * scan->numberOfOrderBys);
}
scan->opaque = so;