Changeset: 47492881fa7a for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/47492881fa7a
Modified Files:
gdk/gdk_select.c
Branch: default
Log Message:
Just always use ordered index if available (which is rare).
It's kind of silly to do two binary searches to figure out whether to do
two binary searches.
diffs (54 lines):
diff --git a/gdk/gdk_select.c b/gdk/gdk_select.c
--- a/gdk/gdk_select.c
+++ b/gdk/gdk_select.c
@@ -1986,30 +1986,27 @@ BATselect(BAT *b, BAT *s, const void *tl
MT_lock_unset(&pb->batIdxLock);
}
if (oidxh) {
- /* Is query selective enough to use the ordered index ?
*/
- /* TODO: Test if this heuristic works in practice */
- /*if ((ORDERfnd(b, th) - ORDERfnd(b, tl)) < ((BUN)1000
< bi.count/1000 ? (BUN)1000: bi.count/1000))*/
- if ((ORDERfnd(b, oidxh, th) - ORDERfnd(b, oidxh, tl)) <
bi.count/3) {
- if (view) {
- bat_iterator_end(&bi);
- bi = bat_iterator(b);
- poidx = true; /* using parent oidx */
- vwo = (lng) (view->tbaseoff -
bi.baseoff);
- vwl = b->hseqbase + (oid) vwo + ci.seq
- view->hseqbase;
- vwh = vwl + canditer_last(&ci) - ci.seq;
- vwo = (lng) view->hseqbase - (lng)
b->hseqbase - vwo;
- TRC_DEBUG(ALGO, "Switch from "
ALGOBATFMT " to " ALGOBATFMT " " OIDFMT "-" OIDFMT " hseq " LLFMT "\n",
ALGOBATPAR(view), ALGOBATPAR(b), vwl, vwh, vwo);
- } else {
- vwl = ci.seq;
- vwh = canditer_last(&ci);
- }
+ /* Is query selective enough to use the ordered
+ * index? Finding the boundaries is 2*log(n)
+ * where n is the size of the bat, sorting is
+ * N*log(N) where N is the number of results.
+ * If the sum is less than n (cost of scan),
+ * it's cheaper. However, to find out how large
+ * N is, we'd have to do the two boundary
+ * searches. If we do that, we might as well do
+ * it all. */
+ if (view) {
+ bat_iterator_end(&bi);
+ bi = bat_iterator(b);
+ poidx = true; /* using parent oidx */
+ vwo = (lng) (view->tbaseoff - bi.baseoff);
+ vwl = b->hseqbase + (oid) vwo + ci.seq -
view->hseqbase;
+ vwh = vwl + canditer_last(&ci) - ci.seq;
+ vwo = (lng) view->hseqbase - (lng) b->hseqbase
- vwo;
+ TRC_DEBUG(ALGO, "Switch from " ALGOBATFMT " to
" ALGOBATFMT " " OIDFMT "-" OIDFMT " hseq " LLFMT "\n", ALGOBATPAR(view),
ALGOBATPAR(b), vwl, vwh, vwo);
} else {
- if (view) {
- b = view;
- view = NULL;
- }
- HEAPdecref(oidxh, false);
- oidxh = NULL;
+ vwl = ci.seq;
+ vwh = canditer_last(&ci);
}
}
}
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