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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2015-05-15 14:26:51 +0300 |
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| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2015-05-15 14:26:51 +0300 |
| commit | 35fcb1b3d038a501f3f4c87c05630095abaaadab (patch) | |
| tree | d67f36684fb18b8523e78f13c0a358b376f50d4b /src/backend/access/gist/gistscan.c | |
| parent | ecd222e770d352121590363ffdf981147a43e976 (diff) | |
| download | postgresql-35fcb1b3d038a501f3f4c87c05630095abaaadab.tar.gz postgresql-35fcb1b3d038a501f3f4c87c05630095abaaadab.zip | |
Allow GiST distance function to return merely a lower-bound.
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
Diffstat (limited to 'src/backend/access/gist/gistscan.c')
| -rw-r--r-- | src/backend/access/gist/gistscan.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/src/backend/access/gist/gistscan.c b/src/backend/access/gist/gistscan.c index 6f653982302..099849a606b 100644 --- a/src/backend/access/gist/gistscan.c +++ b/src/backend/access/gist/gistscan.c @@ -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; |