Update of /cvsroot/monetdb/pathfinder/compiler/algebra/opt
In directory 23jxhf1.ch3.sourceforge.com:/tmp/cvs-serv25521/algebra/opt
Modified Files:
opt_monetxq.c
Log Message:
-- Clean up MonetDB-specific optimizations
-- more documentation
U opt_monetxq.c
Index: opt_monetxq.c
===================================================================
RCS file: /cvsroot/monetdb/pathfinder/compiler/algebra/opt/opt_monetxq.c,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -d -r1.5 -r1.6
--- opt_monetxq.c 15 Apr 2009 10:49:02 -0000 1.5
+++ opt_monetxq.c 20 Apr 2009 08:10:31 -0000 1.6
@@ -224,16 +224,27 @@
}
}
+/**
+ * Introduce additional projection operators
+ * (based in the available icols information)
+ * thus reducing the schema width.
+ */
static void
opt_monetprojections (PFla_op_t *p)
{
assert(p);
+ /* nothing to do if we already visited that node */
+ if (SEEN(p))
+ return;
+ /* otherwise mark the node */
+ else
+ SEEN(p) = true;
+
/* infer properties for children */
for (unsigned int i = 0; i < PFLA_OP_MAXCHILD && p->child[i]; i++)
opt_monetprojections (p->child[i]);
-
/* action code */
switch (p->kind) {
@@ -244,42 +255,49 @@
* p
* |
*/
- case la_pos_select:
- case la_select:
+ case la_attach:
+ case la_cross:
case la_eqjoin:
case la_thetajoin:
- case la_guide_step_join:
- case la_step_join:
- case la_roots:
- case la_cross:
- case la_rownum:
- case la_rowrank:
- case la_rank:
- case la_rowid:
+ case la_select:
+ case la_pos_select:
case la_fun_1to1:
- case la_num_gt:
case la_num_eq:
+ case la_num_gt:
case la_bool_and:
- case la_bool_not:
case la_bool_or:
+ case la_bool_not:
+ case la_to:
+ case la_rownum:
+ case la_rowrank:
+ case la_rank:
+ case la_rowid:
case la_type:
- if (PFprop_icols_count(p->prop)) {
- /* look up required columns (icols) */
- PFalg_collist_t *icols = PFprop_icols_to_collist (p->prop);
- PFalg_proj_t *proj = PFmalloc (clsize (icols) *
- sizeof (PFalg_proj_t));
-
- /* fill the projection list of the lower projection (proj1) */
- for (unsigned int i = 0; i < clsize (icols); i++)
- proj[i] = PFalg_proj (clat (icols, i), clat (icols, i));
-
- /* Place a pi_(icols) operator on top of the operator. */
- *p = *PFla_project_ (
- PFla_op_duplicate (p, L(p), R(p)),
- clsize (icols),
- proj);
+ case la_cast:
+ case la_step_join:
+ case la_guide_step_join:
+ case la_doc_index_join:
+ case la_doc_access:
+ case la_roots:
+ if (PFprop_icols_count(p->prop)) {
+ /* look up required columns (icols) */
+ PFalg_collist_t *icols = PFprop_icols_to_collist (p->prop);
+ PFalg_proj_t *proj = PFmalloc (clsize (icols) *
+ sizeof (PFalg_proj_t));
+
+ /* fill the projection list of the lower projection (proj1) */
+ for (unsigned int i = 0; i < clsize (icols); i++)
+ proj[i] = PFalg_proj (clat (icols, i), clat (icols, i));
+
+ /* Place a pi_(icols) operator on top of the operator. */
+ *p = *PFla_project_ (
+ PFla_op_duplicate (p, L(p), R(p)),
+ clsize (icols),
+ proj);
+ /* mark the new projection node as SEEN */
+ SEEN(p) = true;
+ }
break;
- }
default:
break;
@@ -290,6 +308,7 @@
* MonetDB/XQuery specific optimizations:
* - Introduce additional distinct operators.
* - Rewrite //_[child::a] steps into //a/parent::_ steps
+ * - Introduce additional projection operators (to reduce the schema width).
*/
PFla_op_t *
PFalgopt_monetxq (PFla_op_t *root)
@@ -308,13 +327,19 @@
will ensure that these columns are 'really' never used. */
root = PFalgopt_icol (root);
- /* start second transversal rewrite */
+ PFprop_infer_icol (root);
+
+ /* In a second traversal introduce projections where possible
+ to restrict the schema width. (This leads to better physical
+ path step planning and reduces the complexity of the enumeration
+ process in the planner.) */
opt_monetprojections (root);
+
+ PFla_dag_reset (root);
/* In addition optimize the resulting DAG using the icols property
- to remove inconsistencies introduced by changing the types
- of unreferenced columns (rule eqjoin). The icols optimization
- will ensure that these columns are 'really' never used. */
+ to remove schema inconsistencies. The icols optimization
+ will ensure that unreferenced columns are 'really' never used. */
root = PFalgopt_icol (root);
return root;
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