Changeset: e349732a4384 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/e349732a4384
Modified Files:
sql/storage/bat/bat_storage.c
Branch: faster_segs_end
Log Message:
Improve segs_end performance
Reduces the computation time required in the segs_end function, which could
become a bottleneck due to acquiring a table lock and because it is called many
times per transaction. The apparent tradeoff is that down the line more blocks
might need to be filtered, but the advantages outweigh this.
diffs (34 lines):
diff --git a/sql/storage/bat/bat_storage.c b/sql/storage/bat/bat_storage.c
--- a/sql/storage/bat/bat_storage.c
+++ b/sql/storage/bat/bat_storage.c
@@ -412,19 +412,19 @@ static size_t
segs_end( segments *segs, sql_trans *tr, sql_table *table)
{
size_t cnt = 0;
-
lock_table(tr->store, table->base.id);
- segment *s = segs->h, *l = NULL;
-
- if (segs->t && SEG_IS_VALID(segs->t, tr))
- l = s = segs->t;
-
- for(;s; s = s->next) {
- if (SEG_IS_VALID(s, tr))
- l = s;
+ if (segs->t) {
+ cnt = segs->t->end;
}
- if (l)
- cnt = l->end;
+ else { /* shouldn't really happen but its here just in case */
+ segment *s = segs->h;
+ while (s->next) {
+ s = s->next;
+ }
+ if (s) {
+ cnt = s->end;
+ }
+ }
unlock_table(tr->store, table->base.id);
return cnt;
}
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