Changeset: 94bd4ac58a90 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/94bd4ac58a90
Modified Files:
gdk/gdk_batop.c
Branch: Mar2025
Log Message:
Added some special casing in case multiple identical values are updated.
If multiple identical values (same pointer into source vheap) are
updated in a row, we recognize that and will reuse the offset from the
first in the row without going through the whole process we normally
use to insert a value.
Also, we reduce the number of comparisons when checking whether the
new value is now the new smallest/largest value: if it was the same
value as the previous, we already know the answer. And when we've
updated the smallest/largest value, we know a subsequent
to-be-replaced value cannot be the smallest/largest, so we can skip
that comparison as well.
diffs (83 lines):
diff --git a/gdk/gdk_batop.c b/gdk/gdk_batop.c
--- a/gdk/gdk_batop.c
+++ b/gdk/gdk_batop.c
@@ -1323,6 +1323,11 @@ BATappend_or_update(BAT *b, BAT *p, cons
bool locked = false;
if (b->tvheap) {
+ const void *prevnew = NULL;
+ var_t prevoff = 0;
+ const bool hasdel = BATatoms[b->ttype].atomDel != NULL;
+ bool minupdated = false;
+ bool maxupdated = false;
for (BUN i = 0; i < ni.count; i++) {
oid updid;
if (positions) {
@@ -1399,13 +1404,22 @@ BATappend_or_update(BAT *b, BAT *p, cons
b->tnil |= isnil;
MT_lock_unset(&b->theaplock);
if (bi.maxpos != BUN_NONE) {
+ /* if new value is the same as the
+ * previous new value, we've already
+ * dealt with it; if we've already
+ * updated the maxpos, it cannot be the
+ * same as the old value, so we can skip
+ * that check */
if (!isnil &&
+ (prevnew == NULL || prevnew != new) &&
atomcmp(BUNtvar(bi, bi.maxpos), new) < 0) {
/* new value is larger than
* previous largest */
bi.maxpos = updid;
+ maxupdated = true;
} else if (old == NULL ||
- (atomcmp(BUNtvar(bi, bi.maxpos),
old) == 0 &&
+ (!maxupdated &&
+ atomcmp(BUNtvar(bi, bi.maxpos),
old) == 0 &&
atomcmp(new, old) != 0)) {
/* old value is equal to
* largest and new value is
@@ -1417,12 +1431,15 @@ BATappend_or_update(BAT *b, BAT *p, cons
}
if (bi.minpos != BUN_NONE) {
if (!isnil &&
+ (prevnew == NULL || prevnew != new) &&
atomcmp(BUNtvar(bi, bi.minpos), new) > 0) {
/* new value is smaller than
* previous smallest */
bi.minpos = updid;
+ minupdated = true;
} else if (old == NULL ||
- (atomcmp(BUNtvar(bi, bi.minpos),
old) == 0 &&
+ (!minupdated &&
+ atomcmp(BUNtvar(bi, bi.minpos),
old) == 0 &&
atomcmp(new, old) != 0)) {
/* old value is equal to
* smallest and new value is
@@ -1463,7 +1480,16 @@ BATappend_or_update(BAT *b, BAT *p, cons
MT_UNREACHABLE();
}
MT_lock_set(&b->theaplock);
- gdk_return rc = ATOMreplaceVAR(b, &d, new);
+ gdk_return rc = GDK_SUCCEED;
+ bool skip = false;
+ if (new == prevnew && !hasdel) {
+ d = prevoff;
+ skip = true;
+ } else {
+ rc = ATOMreplaceVAR(b, &d, new);
+ prevnew = new;
+ prevoff = d;
+ }
MT_lock_unset(&b->theaplock);
if (rc != GDK_SUCCEED) {
goto bailout;
@@ -1478,7 +1504,7 @@ BATappend_or_update(BAT *b, BAT *p, cons
/* in case ATOMreplaceVAR and/or
* GDKupgradevarheap replaces a heap, we need to
* reinitialize the iterator */
- {
+ if (!skip) {
/* save and restore minpos/maxpos */
BUN minpos = bi.minpos;
BUN maxpos = bi.maxpos;
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