Changeset: 11c0c6cf614f for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=11c0c6cf614f
Modified Files:
gdk/gdk_search.c
Branch: default
Log Message:
Merged with Oct2014 branch.
diffs (53 lines):
diff --git a/gdk/gdk_search.c b/gdk/gdk_search.c
--- a/gdk/gdk_search.c
+++ b/gdk/gdk_search.c
@@ -98,10 +98,13 @@ HASHwidth(BUN hashsize)
BUN
HASHmask(BUN cnt)
{
- BUN m = 1 << 8; /* minimum size */
+ BUN m = 1 << 8; /* minimum size; == BATTINY */
+ /* find largest power of 2 smaller than cnt */
while (m + m < cnt)
m += m;
+ /* if cnt is more than 1/3 into the gap between m & 2*m,
+ double m */
if (m + m - cnt < 2 * (cnt - m))
m += m;
return m;
@@ -321,7 +324,7 @@ BAThash(BAT *b, BUN masksize)
if (b->T->hash == NULL) {
unsigned int tpe = ATOMbasetype(b->ttype);
BUN cnt = BATcount(b);
- BUN mask;
+ BUN mask, maxmask = 0;
BUN p = BUNfirst(b), q = BUNlast(b), r;
Hash *h = NULL;
Heap *hp;
@@ -369,11 +372,12 @@ BAThash(BAT *b, BUN masksize)
mask = HASHmask(cnt);
} else {
/* dynamic hash: we start with
- * HASHmask(cnt/64); if there are too many
- * collisions we try HASHmask(cnt/16), then
- * HASHmask(cnt/4), and finally
+ * HASHmask(cnt)/64; if there are too many
+ * collisions we try HASHmask(cnt)/16, then
+ * HASHmask(cnt)/4, and finally
* HASHmask(cnt). */
- mask = HASHmask(cnt >> 6);
+ maxmask = HASHmask(cnt);
+ mask = maxmask >> 6;
p += (cnt >> 2); /* try out on first 25% of b */
if (p > q)
p = q;
@@ -453,7 +457,7 @@ BAThash(BAT *b, BUN masksize)
}
break;
}
- } while (r < p && mask < cnt && (mask <<= 2));
+ } while (r < p && mask < maxmask && (mask <<= 2));
/* finish the hashtable with the current mask */
p = r;
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