Changeset: cc38895a41e1 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=cc38895a41e1
Modified Files:
gdk/gdk_select.c
Branch: Oct2014
Log Message:
Determine whether subselect result is dense and convert to void bat.
diffs (55 lines):
diff --git a/gdk/gdk_select.c b/gdk/gdk_select.c
--- a/gdk/gdk_select.c
+++ b/gdk/gdk_select.c
@@ -46,6 +46,33 @@ float nextafterf(float x, float y);
} while (0)
static BAT *
+virtualize(BAT *bn)
+{
+ assert(bn == NULL ||
+ ((bn->ttype == TYPE_void || bn->ttype == TYPE_oid) &&
+ bn->tkey && bn->tsorted));
+ /* since bn has unique and strictly ascending tail values, we
+ * can easily check whether the tail is dense */
+ if (bn && !BATtdense(bn) &&
+ * (const oid *) Tloc(bn, BUNfirst(bn)) + BATcount(bn) - 1 ==
+ * (const oid *) Tloc(bn, BUNlast(bn) - 1)) {
+ /* tail is dense, replace by virtual oid */
+ ALGODEBUG fprintf(stderr,
"#virtualize(bn=%s#"BUNFMT",seq="OIDFMT")\n",
+ BATgetId(bn), BATcount(bn),
+ * (const oid *) Tloc(bn, BUNfirst(bn)));
+ bn->tseqbase = * (const oid *) Tloc(bn, BUNfirst(bn));
+ bn->tdense = 1;
+ HEAPfree(&bn->T->heap);
+ bn->ttype = TYPE_void;
+ bn->tvarsized = 1;
+ bn->T->width = 0;
+ bn->T->shift = 0;
+ }
+
+ return bn;
+}
+
+static BAT *
newempty(const char *func)
{
BAT *bn = BATnew(TYPE_void, TYPE_void, 0, TRANSIENT);
@@ -1252,7 +1279,7 @@ BATsubselect(BAT *b, BAT *s, const void
bn->hrevsorted = bn->batCount <= 1;
bn->H->nonil = 1;
bn->H->nil = 0;
- return bn;
+ return virtualize(bn);
}
/* upper limit for result size */
@@ -1377,7 +1404,7 @@ BATsubselect(BAT *b, BAT *s, const void
lval, hval, maximum, use_imprints);
}
- return bn;
+ return virtualize(bn);
}
/* theta select
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