Update of /cvsroot/monetdb/pathfinder/compiler/algebra/opt
In directory sc8-pr-cvs16.sourceforge.net:/tmp/cvs-serv18522/algebra/opt
Modified Files:
Tag: XQuery_0-24
opt_const.c
Log Message:
-- Fixing bug #1981827:
It is incorrect to rewrite a grouped aggregate into an ungrouped one
without taking the cardinality (and thus the loop relation) into account.
Out of nowhere (no row) something (a row) pops up...
U opt_const.c
Index: opt_const.c
===================================================================
RCS file: /cvsroot/monetdb/pathfinder/compiler/algebra/opt/opt_const.c,v
retrieving revision 1.32
retrieving revision 1.32.2.1
diff -u -d -r1.32 -r1.32.2.1
--- opt_const.c 21 May 2008 10:52:07 -0000 1.32
+++ opt_const.c 2 Jun 2008 16:32:42 -0000 1.32.2.1
@@ -455,37 +455,45 @@
and replace it by an unpartitioned count */
if (p->schema.count == 1 &&
L(p)->kind == la_project &&
- L(L(p))->kind == la_count &&
- PFprop_const (L(L(p))->prop, L(L(p))->sem.aggr.part) &&
+ LL(p)->kind == la_count &&
+ PFprop_const (LL(p)->prop, LL(p)->sem.aggr.part) &&
+ L(p)->sem.proj.items[0].old == LL(p)->sem.aggr.res &&
R(p)->kind == la_project &&
- L(R(p))->kind == la_attach &&
- L(R(p))->sem.attach.value.type == aat_int &&
- L(R(p))->sem.attach.value.val.int_ == 0 &&
- L(L(R(p)))->kind == la_difference &&
- R(L(L(R(p))))->kind == la_project &&
- R(L(L(R(p))))->sem.proj.items[0].new ==
- L(L(p))->sem.aggr.part &&
- L(R(L(L(R(p))))) == L(L(p))) {
+ RL(p)->kind == la_attach &&
+ R(p)->sem.proj.items[0].old == RL(p)->sem.attach.res &&
+ RL(p)->sem.attach.value.type == aat_int &&
+ RL(p)->sem.attach.value.val.int_ == 0 &&
+ RLL(p)->kind == la_difference &&
+ RLLR(p)->kind == la_project &&
+ RLLR(p)->sem.proj.items[0].old ==
+ LL(p)->sem.aggr.part &&
+ L(RLLR(p)) == LL(p)) {
/* check that the values in the loop are constant
and provide the same value */
- assert (PFprop_const (L(L(L(R(p))))->prop,
- L(L(p))->sem.aggr.part));
+ assert (PFprop_const (RLLL(p)->prop,
+ LL(p)->sem.aggr.part));
assert (
PFalg_atom_comparable (
- PFprop_const_val (L(L(L(R(p))))->prop,
- L(L(p))->sem.aggr.part),
- PFprop_const_val (L(L(p))->prop,
- L(L(p))->sem.aggr.part)) &&
+ PFprop_const_val (RLLL(p)->prop,
+ RLLR(p)->sem.proj.items[0].new),
+ PFprop_const_val (LL(p)->prop,
+ LL(p)->sem.aggr.part)) &&
!PFalg_atom_cmp (
- PFprop_const_val (L(L(L(R(p))))->prop,
- L(L(p))->sem.aggr.part),
- PFprop_const_val (L(L(p))->prop,
- L(L(p))->sem.aggr.part)));
+ PFprop_const_val (RLLL(p)->prop,
+ RLLR(p)->sem.proj.items[0].new),
+ PFprop_const_val (LL(p)->prop,
+ LL(p)->sem.aggr.part)));
- *p = *PFla_count (L(L(L(p))),
- p->schema.items[0].name,
- att_NULL);
+ /* To avoid creating more results than allowed (1 instead
+ of 0) we have to make sure that we take the cardinality
+ of the loop relation into account. */
+ *p = *project (cross (RLLL(p), /* loop */
+ PFla_count (LLL(p),
+ R(p)->sem.proj.items[0].old,
+ att_NULL)),
+ proj (R(p)->sem.proj.items[0].new,
+ R(p)->sem.proj.items[0].old));
break;
}
break;
@@ -659,6 +667,11 @@
/* some optimization opportunities for
aggregate operators arise if 'att' is constant */
if (PFprop_const_left (p->prop, p->sem.aggr.att)) {
+
+#if 0 /* We are not allowed to create an unpartitioned aggregate
+ as an empty loop relation might result in a single line
+ result otherwise. */
+
/* if partitioning column is constant as well
replace aggregate by a new literal table
with one row containing 'att' and 'part' */
@@ -677,6 +690,7 @@
constant we can replace the aggregate by a
distinct operator (value in 'att' stays the same). */
else if (p->sem.aggr.part)
+#endif
*p = *PFla_distinct (
PFla_project (
L(p),
@@ -684,6 +698,7 @@
p->sem.aggr.att),
PFalg_proj (p->sem.aggr.part,
p->sem.aggr.part)));
+#if 0
/* replace aggregate by a new literal table
containining a single record with the result of
aggregate operator. */
@@ -693,6 +708,7 @@
PFprop_const_val_left (
p->prop,
p->sem.aggr.att)));
+#endif
}
break;
@@ -704,6 +720,10 @@
p->sem.aggr.att));
}
+#if 0 /* We are not allowed to create an unpartitioned aggregate
+ as an empty loop relation might result in a single line
+ result otherwise. */
+
/* if partitiong attribute is constant remove it
and attach it after the operator */
if (p->sem.aggr.part &&
@@ -739,6 +759,7 @@
*p = *ret;
SEEN(p) = true;
}
+#endif
break;
case la_rownum:
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