Update of /cvsroot/monetdb/pathfinder/compiler/sql
In directory sc8-pr-cvs16.sourceforge.net:/tmp/cvs-serv32497/sql
Modified Files:
lalg2sql.brg
Log Message:
-- Introduced a different implementation for descendant and child steps
if the environment variable PF_USE_DB2_SELECTIVITY is set to 1.
(The code then uses SELECTIVITY clauses to give the DB2 optimizer
hints about the result size of the path step.)
Index: lalg2sql.brg
===================================================================
RCS file: /cvsroot/monetdb/pathfinder/compiler/sql/lalg2sql.brg,v
retrieving revision 1.90
retrieving revision 1.91
diff -u -d -r1.90 -r1.91
--- lalg2sql.brg 26 Nov 2007 10:09:21 -0000 1.90
+++ lalg2sql.brg 26 Nov 2007 12:36:03 -0000 1.91
@@ -37,6 +37,7 @@
#include <assert.h>
#include <stdio.h>
#include <string.h>
+#include <stdlib.h>
#include "lalg2sql.h"
#include "alg_dag.h"
@@ -971,8 +972,11 @@
static void
step_axis (PFla_op_t *p, PFsql_aident_t ctx, PFsql_aident_t step,
- PFalg_axis_t axis, PFsql_t *fragment)
+ PFalg_axis_t axis, PFsql_t *fragment, int level_in)
{
+ char *selectivity_str = getenv ("PF_USE_DB2_SELECTIVITY");
+ bool selectivity = selectivity_str && !strcmp (selectivity_str, "1");
+
switch (axis) {
/* ancestor axis */
case alg_anc:
@@ -996,16 +1000,64 @@
case alg_chld:
/* attribute axis */
case alg_attr:
- where_list_add (WHERELIST(p),
- between (PRE(step), add (PRE(ctx), lit_int (1)),
- add (PRE(ctx), SIZE(ctx))));
+ if (selectivity) {
+ if ((level_in == 0 || level_in == 1) &&
+ /* check for steps from a single document */
+ L(p)->kind == la_frag_union &&
+ LL(p)->kind == la_empty_frag &&
+ LR(p)->kind == la_fragment &&
+ L(LR(p))->kind == la_doc_tbl) {
+ where_list_add (WHERELIST(p),
+ selectivity (gt (PRE(step), PRE(ctx)),
+ lit_dec (1)));
+ where_list_add (WHERELIST(p),
+ selectivity (gteq (add (PRE(ctx),
SIZE(ctx)),
+ PRE(step)),
+ lit_dec (1)));
+ } else {
+ where_list_add (WHERELIST(p),
+ selectivity (gt (PRE(step), PRE(ctx)),
+ lit_dec (0.01)));
+ where_list_add (WHERELIST(p),
+ selectivity (gteq (add (PRE(ctx),
SIZE(ctx)),
+ PRE(step)),
+ lit_dec (0.01)));
+ }
+ } else
+ where_list_add (WHERELIST(p),
+ between (PRE(step), add (PRE(ctx), lit_int
(1)),
+ add (PRE(ctx), SIZE(ctx))));
break;
/* descendant-or-self axis */
case alg_desc_s:
- where_list_add (WHERELIST(p),
- between (PRE(step), PRE(ctx),
- add (PRE(ctx), SIZE(ctx))));
+ if (selectivity) {
+ if ((level_in == 0 || level_in == 1) &&
+ /* check for steps from a single document */
+ L(p)->kind == la_frag_union &&
+ LL(p)->kind == la_empty_frag &&
+ LR(p)->kind == la_fragment &&
+ L(LR(p))->kind == la_doc_tbl) {
+ where_list_add (WHERELIST(p),
+ selectivity (gteq (PRE(step), PRE(ctx)),
+ lit_dec (1)));
+ where_list_add (WHERELIST(p),
+ selectivity (gteq (add (PRE(ctx),
SIZE(ctx)),
+ PRE(step)),
+ lit_dec (1)));
+ } else {
+ where_list_add (WHERELIST(p),
+ selectivity (gteq (PRE(step), PRE(ctx)),
+ lit_dec (0.01)));
+ where_list_add (WHERELIST(p),
+ selectivity (gteq (add (PRE(ctx),
SIZE(ctx)),
+ PRE(step)),
+ lit_dec (0.01)));
+ }
+ } else
+ where_list_add (WHERELIST(p),
+ between (PRE(step), PRE(ctx),
+ add (PRE(ctx), SIZE(ctx))));
break;
/* following-sibling axis */
@@ -1902,10 +1954,7 @@
else {
doc2 = new_alias ();
from_list_add (FROMLIST(p), frags, doc2);
- where_list_add (WHERELIST(p),
- between (PRE(doc2),
- PRE(doc1),
- add (PRE(doc1),
SIZE(doc1))));
+ step_axis (p, doc1, doc2, alg_desc_s, NULL, -1);
orderby = sortkey_list (orderby,
sortkey_item (PRE(doc2),
true));
}
@@ -1956,6 +2005,9 @@
from = from_list_at (FROMLIST(query), 0);
from_bind = alias_bind (from.table, alias (from.alias));
+ /* add the axis conditions */
+ step_axis (p, doc1, doc2, alg_desc_s, NULL, -1);
+
finalquery = PFsql_select (
distinct,
select_list (
@@ -1974,10 +2026,7 @@
alias (doc1))),
eq (PRE(doc1), item_expr)),
alias_bind (frags, alias (doc2))),
- between (PRE(doc2),
- PRE(doc1),
- add (PRE(doc1),
- SIZE(doc1))))),
+ transform_wheremap (p))),
NULL,
sortkey_list (orderby,
sortkey_item (PRE(doc2), true)),
@@ -3493,7 +3542,8 @@
ctxalias,
stepalias,
p->sem.step.axis,
- FRAG(L(p)));
+ FRAG(L(p)),
+ PFprop_level (R(p)->prop, p->sem.step.item));
if (p->kind == la_step || p->kind == la_step_join) {
step_name (p, stepalias, p->sem.step.ty);
@@ -4058,7 +4108,7 @@
step = new_alias ();
from_list_add (FROMLIST(p), NULL, step);
/* add the axis conditions */
- step_axis (p, ctx, step, alg_desc_s, NULL);
+ step_axis (p, ctx, step, alg_desc_s, NULL, -1);
selectlist = select_list (
column_assign (iter_expr, ITER_),
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