Changeset: 618d4826c2cd for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/618d4826c2cd
Modified Files:
monetdb5/optimizer/opt_mitosis.c
Branch: default
Log Message:
Slightly increasing the number of partitions improves the larger
scalefactors without affecting too much the smaller ones.
diffs (20 lines):
diff --git a/monetdb5/optimizer/opt_mitosis.c b/monetdb5/optimizer/opt_mitosis.c
--- a/monetdb5/optimizer/opt_mitosis.c
+++ b/monetdb5/optimizer/opt_mitosis.c
@@ -179,11 +179,14 @@ OPTmitosisImplementation(Client cntxt, M
* i.e., (rowcnt/pieces <= m/threads),
* i.e., (pieces => rowcnt/(m/threads))
* (assuming that (m > threads*MINPARTCNT)) */
- pieces = (int) (rowcnt / (m / threads)) + 1;
+ /* the number of pieces affects SF-100, going beyond 8x
increases
+ * the optimizer costs beyond the execution time
+ */
+ pieces = 4 * ceil((double)rowcnt / m / threads);
} else if (rowcnt > MINPARTCNT) {
/* exploit parallelism, but ensure minimal partition size to
* limit overhead */
- pieces = (int) MIN(rowcnt / MINPARTCNT, (BUN) threads);
+ pieces = 4 * ceil(MIN((double)rowcnt / MINPARTCNT,
threads));
}
}
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