Sorry , previous version has bugs. It stamps over the stack and
crashesX( The attached is the bug fixed version, with no
substantial changes.
> On Tue, Jul 15, 2014 at 2:17 PM, Kyotaro HORIGUCHI <
> [email protected]> wrote:
> >
> > Hi, the attached is the revised version.
>
> Thanks Horiguchi-San for the updated patch.
# By the way, this style of calling a person is quite common
# among Japanese since the first-name basis implies very close
# relationship or it frequently conveys offensive shade. But I'm
# not sure what should I call others who're not Japases native.
Anyway,
> Today while looking into updated patch, I was wondering why can't
> we eliminate useless keys in query_pathkeys when we actually build
> the same in function standard_qp_callback(), basically somewhat
> similar to what we do in
> standard_qp_callback->make_pathkeys_for_sortclauses->pathkey_is_redundant().
I agree that standard_qp_callback is basically more preferable.
> We already have index information related to base_rels before building
> query pathkeys. I noticed that you mentioned the below in your original
> mail which indicates that information related to inheritance tables is built
> only after set_base_rel_sizes()
>
> "These steps take place between set_base_rel_sizes() and
> set_base_rel_pathlists() in make_one_rel(). The reason for the
> position is that the step 2 above needs all inheritence tables to
> be extended in PlannerInfo and set_base_rel_sizes (currently)
> does that".
Sorry, my memory had been worn down. After some reconfirmation,
this description found to be a bit (quite?) wrong.
collect_common_primary_pathkeys needs root->eq_classes to be set
up beforehand, not appendrels. Bacause build_index_pathkeys
doesn't work before every EC member for all relation involved is
already registered.
standard_qp_callback registers EC members in the following path
but only for the primary(?) tlist of the subquery, so EC members
for the child relations are not registered at the time.
.->make_pathekeys_sortclauses->make_pathkey_from_sortop
->make_pathkey_from_sortinfo->get_eclass_for_sort_expr
EC members for the child rels are registered in
set_base_rel_sizes->set_rel_size->set_append_rel_size
->add_child_rel_equivalences
So trim_query_pathkeys (collect_common...) doesn't work before
set_base_rel_sizes(). These EC members needed to be registered at
least if root->query_pathkeys exists so this seems to be done in
standard_qp_callback adding a separate inheritance tree walk.
# rel->has_elcass_joins seems not working but it is not the topic
# here.
> Could you please explain me why the index information built in above
> path is not sufficient or is there any other case which I am missing?
Is the description above enough to be the explaination for the
place? Sorry for the inaccurate description.
regards,
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 9573a9b..546e112 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -1789,9 +1789,11 @@ _outIndexOptInfo(StringInfo str, const IndexOptInfo *node)
/* indexprs is redundant since we print indextlist */
WRITE_NODE_FIELD(indpred);
WRITE_NODE_FIELD(indextlist);
+ /* cached pathkeys are omitted as indexkeys */
WRITE_BOOL_FIELD(predOK);
WRITE_BOOL_FIELD(unique);
WRITE_BOOL_FIELD(immediate);
+ WRITE_BOOL_FIELD(allnotnull);
WRITE_BOOL_FIELD(hypothetical);
/* we don't bother with fields copied from the pg_am entry */
}
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index c81efe9..c12d0e7 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -58,6 +58,7 @@ int geqo_threshold;
join_search_hook_type join_search_hook = NULL;
+static List *collect_common_primary_pathkeys(PlannerInfo *root);
static void set_base_rel_sizes(PlannerInfo *root);
static void set_base_rel_pathlists(PlannerInfo *root);
static void set_rel_size(PlannerInfo *root, RelOptInfo *rel,
@@ -66,6 +67,7 @@ static void set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
Index rti, RangeTblEntry *rte);
static void set_plain_rel_size(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
+static void trim_query_pathkeys(PlannerInfo * root);
static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_foreign_size(PlannerInfo *root, RelOptInfo *rel,
@@ -112,6 +114,203 @@ static void recurse_push_qual(Node *setOp, Query *topquery,
RangeTblEntry *rte, Index rti, Node *qual);
static void remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel);
+/*
+ * collect_common_primary_pathkeys: Collects common unique and non-null index
+ * pathkeys from all base relations in current root.
+ */
+static List *
+collect_common_primary_pathkeys(PlannerInfo *root)
+{
+ List *result = NIL;
+ Index rti;
+ int nindex = 0;
+ List **pathkeys_array0 = NULL;
+ List **pathkeys_array = NULL;
+ List **pathkeys_array2 = NULL;
+ bool do_conjunction = (root->simple_rel_array_size > 2);
+
+ for (rti = 1 ; rti < root->simple_rel_array_size ; rti++)
+ {
+ RelOptInfo *rel = root->simple_rel_array[rti];
+ int prev_nindex = 0;
+ ListCell *lc;
+
+ if (rel == NULL)
+ continue;
+
+ Assert (rel->relid == rti);
+
+ prev_nindex = nindex;
+ nindex = 0;
+
+ /* Scan all base relations except parent relations. */
+ if (root->simple_rte_array[rti]->inh ||
+ (rel->reloptkind != RELOPT_BASEREL &&
+ rel->reloptkind != RELOPT_OTHER_MEMBER_REL))
+ continue;
+
+ if (do_conjunction)
+ {
+ if (pathkeys_array2)
+ memset(pathkeys_array2, 0, sizeof(List*) * nindex);
+ else
+ {
+ /* Rig for AND (conjunction) operation. */
+ int nindex_tmp = 0;
+
+ foreach (lc, rel->indexlist)
+ {
+ IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
+
+ if (index->allnotnull &&
+ index->unique && index->immediate &&
+ index->indpred == NIL)
+ nindex_tmp++;
+ }
+
+ if (nindex_tmp == 0)
+ return NULL; /* No common primary pathkeys exists.*/
+
+ pathkeys_array0 = palloc0(sizeof(List*) * nindex_tmp * 2);
+ pathkeys_array = pathkeys_array0;
+ pathkeys_array2 = pathkeys_array0 + nindex_tmp;
+ }
+ }
+
+ foreach (lc, rel->indexlist)
+ {
+ IndexOptInfo *index = (IndexOptInfo *) lfirst(lc);
+ List *idx_pathkeys;
+
+ /* Only indexes that can unique sort are needed. */
+ if (!index->allnotnull ||
+ !(index->unique && index->immediate) ||
+ index->indpred != NIL)
+ continue;
+
+ idx_pathkeys = build_index_pathkeys(root, index,
+ ForwardScanDirection);
+ if (!idx_pathkeys)
+ continue;
+
+ if (!do_conjunction)
+ {
+ result = lappend(result, idx_pathkeys);
+ nindex++;
+ }
+ else
+ {
+ /*
+ * AND operation: drop pathkeys which don't see identical
+ * one in this relation.
+ */
+ int i;
+
+ for (i = 0 ; i < prev_nindex ; i++)
+ {
+ if (compare_pathkeys(pathkeys_array[i],
+ idx_pathkeys,
+ false) == PATHKEYS_EQUAL)
+ break;
+ }
+ if (prev_nindex < 1 || i < prev_nindex)
+ pathkeys_array2[nindex++] = idx_pathkeys;
+ }
+ }
+
+ if (nindex == 0)
+ {
+ /* No common primary pathkeys remained, exit. */
+ if (pathkeys_array0)
+ pfree(pathkeys_array0);
+ return NULL;
+ }
+
+ if (do_conjunction)
+ {
+ List **pktmp;
+
+ /* swap two pathkeys arrays for the next iteration */
+ pktmp = pathkeys_array2;
+ pathkeys_array2 = pathkeys_array;
+ pathkeys_array = pktmp;
+ }
+ }
+
+ if (do_conjunction)
+ {
+ int i;
+
+ for (i = 0 ; i < nindex ; i++)
+ {
+ if (pathkeys_array[i])
+ result = lappend(result, pathkeys_array[i]);
+ }
+ pfree(pathkeys_array0);
+ }
+
+ return result;
+}
+
+/*
+ * trim_query_pathkeys: trim pathkeys following common primary pathkeys.
+ *
+ * Primary pathkeys are pathkeys which perfectly sorts tuples in its owner
+ * table so the query pathkeys can be replaced with the primary pathkeys when
+ * the latter prefixes the former. Common primary pathkeys are the primary
+ * pathkeys shared among all base relations accessed in current root.
+ *
+ * This function doesn't trim RowExpr pathkeys.
+ */
+static void
+trim_query_pathkeys(PlannerInfo * root)
+{
+ ListCell *lc;
+
+ foreach(lc, collect_common_primary_pathkeys(root))
+ {
+ List *pk_guide = (List*) lfirst(lc);
+
+ if (root->sort_pathkeys)
+ {
+ /* sort_pathkeys is not allowd to flip sorting directions
+ * differently from other pathkeys. So try to trim sort_pathkeys
+ * first preserving per-key directions, then try to trim other
+ * pathkeys using the trimmed sort_pathkeys as the guide.
+ */
+
+ root->sort_pathkeys =
+ shorten_pathkeys_following(root, root->sort_pathkeys, pk_guide,
+ false);
+
+ /*
+ * Replace guide pathkeys with new sort_pathkeys if they differs
+ * from each other only by sorting directions.
+ */
+ if (compare_pathkeys(root->sort_pathkeys,
+ pk_guide, false) != PATHKEYS_EQUAL &&
+ compare_pathkeys(root->sort_pathkeys,
+ pk_guide, true) == PATHKEYS_EQUAL)
+ pk_guide = root->sort_pathkeys;
+ }
+
+ root->group_pathkeys =
+ shorten_pathkeys_following(root, root->group_pathkeys, pk_guide,
+ true);
+
+ root->window_pathkeys =
+ shorten_pathkeys_following(root, root->window_pathkeys, pk_guide,
+ true);
+
+ root->distinct_pathkeys =
+ shorten_pathkeys_following(root, root->distinct_pathkeys, pk_guide,
+ true);
+
+ root->query_pathkeys =
+ shorten_pathkeys_following(root, root->query_pathkeys, pk_guide,
+ true);
+ }
+}
/*
* make_one_rel
@@ -149,6 +348,7 @@ make_one_rel(PlannerInfo *root, List *joinlist)
* Generate access paths for the base rels.
*/
set_base_rel_sizes(root);
+ trim_query_pathkeys(root);
set_base_rel_pathlists(root);
/*
@@ -755,7 +955,7 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
List *existing_pathkeys = (List *) lfirst(lpk);
if (compare_pathkeys(existing_pathkeys,
- childkeys) == PATHKEYS_EQUAL)
+ childkeys, false) == PATHKEYS_EQUAL)
{
found = true;
break;
diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c
index 5d953df..6cc9754 100644
--- a/src/backend/optimizer/path/pathkeys.c
+++ b/src/backend/optimizer/path/pathkeys.c
@@ -275,10 +275,13 @@ make_pathkey_from_sortop(PlannerInfo *root,
* one is "better" than the other.
*
* We assume the pathkeys are canonical, and so they can be checked for
- * equality by simple pointer comparison.
+ * equality by simple pointer comparison when ignore_strategy is false.
+ *
+ * If ignore_strategy is true, the two pathkeys with no difference other
+ * than strategy are regarded as the same.
*/
PathKeysComparison
-compare_pathkeys(List *keys1, List *keys2)
+compare_pathkeys(List *keys1, List *keys2, bool ignore_strategy)
{
ListCell *key1,
*key2;
@@ -296,7 +299,23 @@ compare_pathkeys(List *keys1, List *keys2)
PathKey *pathkey1 = (PathKey *) lfirst(key1);
PathKey *pathkey2 = (PathKey *) lfirst(key2);
- if (pathkey1 != pathkey2)
+ if (pathkey1 == pathkey2)
+ continue;
+
+ if (!ignore_strategy)
+ return PATHKEYS_DIFFERENT; /* no need to keep looking */
+
+ Assert(pathkey1->pk_strategy == BTGreaterStrategyNumber ||
+ pathkey1->pk_strategy == BTLessStrategyNumber);
+ Assert(pathkey2->pk_strategy == BTGreaterStrategyNumber ||
+ pathkey2->pk_strategy == BTLessStrategyNumber);
+
+ if (pathkey1->pk_eclass != pathkey2->pk_eclass ||
+ pathkey1->pk_opfamily != pathkey2->pk_opfamily ||
+ !((pathkey1->pk_strategy == pathkey2->pk_strategy &&
+ pathkey1->pk_nulls_first == pathkey2->pk_nulls_first) ||
+ (pathkey1->pk_strategy != pathkey2->pk_strategy &&
+ pathkey1->pk_nulls_first != pathkey2->pk_nulls_first)))
return PATHKEYS_DIFFERENT; /* no need to keep looking */
}
@@ -319,7 +338,7 @@ compare_pathkeys(List *keys1, List *keys2)
bool
pathkeys_contained_in(List *keys1, List *keys2)
{
- switch (compare_pathkeys(keys1, keys2))
+ switch (compare_pathkeys(keys1, keys2, false))
{
case PATHKEYS_EQUAL:
case PATHKEYS_BETTER2:
@@ -440,10 +459,15 @@ build_index_pathkeys(PlannerInfo *root,
List *retval = NIL;
ListCell *lc;
int i;
+ List *cached_pathkeys = (ScanDirectionIsBackward(scandir) ?
+ index->indbwpathkeys : index->indfwpathkeys);
if (index->sortopfamily == NULL)
return NIL; /* non-orderable index */
+ if (cached_pathkeys)
+ return cached_pathkeys; /* Return cached pathkeys if any */
+
i = 0;
foreach(lc, index->indextlist)
{
@@ -498,6 +522,12 @@ build_index_pathkeys(PlannerInfo *root,
i++;
}
+ /* Store created pathkeys for future use */
+ if (ScanDirectionIsBackward(scandir))
+ index->indbwpathkeys = retval;
+ else
+ index->indfwpathkeys = retval;
+
return retval;
}
@@ -1525,3 +1555,87 @@ has_useful_pathkeys(PlannerInfo *root, RelOptInfo *rel)
return true; /* might be able to use them for ordering */
return false; /* definitely useless */
}
+
+/*
+ * shorten_pathkeys_following: returns pk_guide if it prefixes pk_target
+ * regardless of the ordering directions of the pathkeys.
+ * allow_partial_flip allows ordering directions to be partially different
+ * between pk_target and pk_guide.
+ */
+List *
+shorten_pathkeys_following(PlannerInfo *root, List *pk_target, List *pk_guide,
+ bool allow_partial_flip)
+{
+ ListCell *tlc, *glc;
+ int same = 0, reverse = 0;
+ List *result;
+
+ if (pk_target == NIL)
+ return NIL;
+
+ if (list_length(pk_target) < list_length(pk_guide))
+ return pk_target;
+
+ forboth(tlc, pk_target, glc, pk_guide)
+ {
+ PathKey *tpk = (PathKey *) lfirst(tlc);
+ PathKey *gpk = (PathKey *) lfirst(glc);
+
+ if (tpk == gpk)
+ {
+ same++;
+ continue;
+ }
+
+ Assert(tpk->pk_strategy == BTGreaterStrategyNumber ||
+ tpk->pk_strategy == BTLessStrategyNumber);
+ Assert(gpk->pk_strategy == BTGreaterStrategyNumber ||
+ gpk->pk_strategy == BTLessStrategyNumber);
+
+ if (tpk->pk_eclass == gpk->pk_eclass &&
+ tpk->pk_opfamily == gpk->pk_opfamily &&
+ tpk->pk_strategy != gpk->pk_strategy &&
+ tpk->pk_nulls_first != gpk->pk_nulls_first)
+ {
+ reverse++;
+ continue;
+ }
+
+ return pk_target;
+ }
+
+ /* trailing members in pk_target don't matter */
+
+ /* reverse == 0 means that pk_guide exactly prefixes pk_target */
+ if (allow_partial_flip || reverse == 0)
+ return pk_guide;
+
+ /*
+ * Don't replace pathkeys if partial flip is not allowed but partially
+ * flipped.
+ */
+ Assert(reverse > 0);
+ if (same > 0)
+ return pk_target;
+
+ /* make then reutrn the reverse pathkeys of pk_guide */
+ result = NIL;
+ foreach (glc, pk_guide)
+ {
+ PathKey *gpk = (PathKey *) lfirst(glc);
+ PathKey *pk;
+ EquivalenceClass *ec = gpk->pk_eclass;
+ int revstr;
+
+ if (gpk->pk_strategy == BTGreaterStrategyNumber)
+ revstr = BTLessStrategyNumber;
+ else
+ revstr = BTGreaterStrategyNumber;
+
+ pk = make_canonical_pathkey(root, ec, gpk->pk_opfamily, revstr,
+ !gpk->pk_nulls_first);
+
+ result = lappend(result, pk);
+ }
+ return result;
+}
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index d129f8d..9433a40 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -312,14 +312,14 @@ set_cheapest(RelOptInfo *parent_rel)
if (cmp > 0 ||
(cmp == 0 &&
compare_pathkeys(cheapest_startup_path->pathkeys,
- path->pathkeys) == PATHKEYS_BETTER2))
+ path->pathkeys, false) == PATHKEYS_BETTER2))
cheapest_startup_path = path;
cmp = compare_path_costs(cheapest_total_path, path, TOTAL_COST);
if (cmp > 0 ||
(cmp == 0 &&
compare_pathkeys(cheapest_total_path->pathkeys,
- path->pathkeys) == PATHKEYS_BETTER2))
+ path->pathkeys, false) == PATHKEYS_BETTER2))
cheapest_total_path = path;
}
}
@@ -455,7 +455,7 @@ add_path(RelOptInfo *parent_rel, Path *new_path)
old_path_pathkeys = old_path->param_info ? NIL : old_path->pathkeys;
keyscmp = compare_pathkeys(new_path_pathkeys,
- old_path_pathkeys);
+ old_path_pathkeys, false);
if (keyscmp != PATHKEYS_DIFFERENT)
{
switch (costcmp)
@@ -653,7 +653,7 @@ add_path_precheck(RelOptInfo *parent_rel,
old_path_pathkeys = old_path->param_info ? NIL : old_path->pathkeys;
keyscmp = compare_pathkeys(new_path_pathkeys,
- old_path_pathkeys);
+ old_path_pathkeys, false);
if (keyscmp == PATHKEYS_EQUAL ||
keyscmp == PATHKEYS_BETTER2)
{
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index b2becfa..1cebd2b 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -241,12 +241,28 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
info->reverse_sort = (bool *) palloc(sizeof(bool) * ncolumns);
info->nulls_first = (bool *) palloc(sizeof(bool) * ncolumns);
+ info->allnotnull = true;
for (i = 0; i < ncolumns; i++)
{
int16 opt = indexRelation->rd_indoption[i];
+ int16 attno = info->indexkeys[i];
info->reverse_sort[i] = (opt & INDOPTION_DESC) != 0;
info->nulls_first[i] = (opt & INDOPTION_NULLS_FIRST) != 0;
+
+ if (!info->allnotnull) continue;
+
+ /* Check if there's no nullable key column */
+ if (attno > 0)
+ {
+ if (!relation->rd_att->attrs[attno - 1]->attnotnull)
+ info->allnotnull = false;
+ }
+ else if (attno != ObjectIdAttributeNumber)
+ {
+ /* OID is apparently not-null */
+ info->allnotnull = false;
+ }
}
}
else if (indexRelation->rd_am->amcanorder)
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index dacbe9c..4855667 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -524,10 +524,13 @@ typedef struct IndexOptInfo
List *indpred; /* predicate if a partial index, else NIL */
List *indextlist; /* targetlist representing index columns */
+ List *indfwpathkeys; /* index pathkeys for forward scan */
+ List *indbwpathkeys; /* index pathkeys for backwad scan */
bool predOK; /* true if predicate matches query */
bool unique; /* true if a unique index */
bool immediate; /* is uniqueness enforced immediately? */
+ bool allnotnull; /* all columns are "NOT NULL" ? */
bool hypothetical; /* true if index doesn't really exist */
bool canreturn; /* can index return IndexTuples? */
bool amcanorderbyop; /* does AM support order by operator result? */
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 9b22fda..f637fc3 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -146,7 +146,10 @@ typedef enum
PATHKEYS_DIFFERENT /* neither pathkey includes the other */
} PathKeysComparison;
-extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
+extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2,
+ bool ignore_strategy);
+extern PathKeysComparison compare_pathkeys_ignoring_strategy(List *keys1,
+ List *keys2);
extern bool pathkeys_contained_in(List *keys1, List *keys2);
extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
Relids required_outer,
@@ -187,5 +190,8 @@ extern List *truncate_useless_pathkeys(PlannerInfo *root,
RelOptInfo *rel,
List *pathkeys);
extern bool has_useful_pathkeys(PlannerInfo *root, RelOptInfo *rel);
+extern List *shorten_pathkeys_following(PlannerInfo *root,
+ List *pk_target, List *pk_guide,
+ bool allow_partial_flip);
#endif /* PATHS_H */
diff --git a/src/test/isolation/expected/drop-index-concurrently-1.out b/src/test/isolation/expected/drop-index-concurrently-1.out
index 75dff56..ab96fa0 100644
--- a/src/test/isolation/expected/drop-index-concurrently-1.out
+++ b/src/test/isolation/expected/drop-index-concurrently-1.out
@@ -19,10 +19,8 @@ Sort
step explains: EXPLAIN (COSTS OFF) EXECUTE getrow_seq;
QUERY PLAN
-Sort
- Sort Key: id, data
- -> Seq Scan on test_dc
- Filter: ((data)::text = '34'::text)
+Index Scan using test_dc_pkey on test_dc
+ Filter: ((data)::text = '34'::text)
step select2: SELECT * FROM test_dc WHERE data=34 ORDER BY id,data;
id data
--
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