Changeset: f0fa283e6295 for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=f0fa283e6295
Modified Files:
sql/src/backends/monet5/sql_optimizer.mx
Branch: Oct2010
Log Message:
with point queries, next to mitosis, also disable dataflow
It appears that with cheap queries, i.e., queries that need to
process only small amounts of data, runtime dataflow scheduling
becomes the dominating cost factor, eliminating potential benefits
due to multi-core parallel execution of independent operations;
the more that more complex the query is.
Point queries (build and) exploit hash tables to almost "instantly"
(i.e., at low constant costs) reduce potentially large input to
small intermediate results, and hence are rather cheap to run;
hence, just as we already disable mitosis for point queries
(in order to enable the reuse of hash-table on base columns),
we now also disable dataflow for point queries to avoid the
dataflow shcduling overhead at runtime.
diffs (12 lines):
diff -r 8dd1268ab5a6 -r f0fa283e6295 sql/src/backends/monet5/sql_optimizer.mx
--- a/sql/src/backends/monet5/sql_optimizer.mx Thu Oct 07 08:27:15 2010 +0200
+++ b/sql/src/backends/monet5/sql_optimizer.mx Thu Oct 07 09:18:41 2010 +0200
@@ -635,7 +635,7 @@
for (i = 0; optimizers[i]; i++) {
InstrPtr p;
- if (m->point_query && strcmp(optimizers[i], "mitosis")==0)
+ if (m->point_query && (strcmp(optimizers[i], "mitosis")==0 ||
strcmp(optimizers[i], "dataflow")==0))
continue;
p = newFcnCall(mb, "optimizer", optimizers[i]);
typeChecker(c->nspace, mb, p, TRUE);
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