Changeset: 9c37eae89e2e for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/9c37eae89e2e
Modified Files:
monetdb5/optimizer/opt_mitosis.c
Branch: default
Log Message:
crude attempt at reducing extreem fanout of mitosis on self joins.
diffs (53 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
@@ -21,7 +21,7 @@ OPTmitosisImplementation(Client cntxt, M
InstrPtr p, q, *old, target = 0;
size_t argsize = 6 * sizeof(lng), m = 0, memclaim;
/* estimate size per operator estimate: 4 args + 2 res*/
- int threads = GDKnr_threads ? GDKnr_threads : 1;
+ int threads = GDKnr_threads ? GDKnr_threads : 1, maxslices = MAXSLICES;
str msg = MAL_SUCCEED;
/* if the user has associated limitation on the number of threads,
respect it in the
@@ -47,6 +47,9 @@ OPTmitosisImplementation(Client cntxt, M
}
/* mitosis/mergetable bailout conditions */
+ /* Crude protection against self join explosion */
+ if (p->retc == 2 && isMatJoinOp(p))
+ maxslices = threads;
if (p->argc > 2 && getModuleId(p) == aggrRef &&
getFunctionId(p) != subcountRef &&
@@ -152,8 +155,8 @@ OPTmitosisImplementation(Client cntxt, M
* Determine the memory available for this client
*/
- /* respect the memory limit size set for the user
- * and determine the column slice size
+ /* respect the memory limit size set for the user
+ * and determine the column slice size
*/
if( cntxt->memorylimit)
m = (((size_t) cntxt->memorylimit) * 1048576) / argsize;
@@ -175,7 +178,7 @@ OPTmitosisImplementation(Client cntxt, M
* i.e., (rowcnt/pieces <= m/threads),
* i.e., (pieces => rowcnt/(m/threads))
* (assuming that (m > threads*MINPARTCNT)) */
- /* the number of pieces affects SF-100, going beyond 8x
increases
+ /* the number of pieces affects SF-100, going beyond 8x
increases
* the optimizer costs beyond the execution time
*/
pieces = 4 * (int) ceil((double)rowcnt / m / threads);
@@ -192,8 +195,8 @@ OPTmitosisImplementation(Client cntxt, M
if (pieces < threads)
pieces = (int) MIN((BUN) threads, rowcnt);
/* prevent plan explosion */
- if (pieces > MAXSLICES)
- pieces = MAXSLICES;
+ if (pieces > maxslices)
+ pieces = maxslices;
/* to enable experimentation we introduce the option to set
* the number of parts required and/or the size of each chunk (in K)
*/
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