List *restrictlist,
List **extra_clauses);
static int self_join_candidates_cmp(const void *a, const void *b);
+static bool replace_relid_callback(Node *node,
+ ChangeVarNodes_context *context);
/*
{
Assert(subst > 0);
- ChangeVarNodes((Node *) sjinf->semi_rhs_exprs, relid, subst, 0);
+ ChangeVarNodesExtended((Node *) sjinf->semi_rhs_exprs, relid, subst,
+ 0, replace_relid_callback);
}
}
sjinfo->ojrelid, subst);
Assert(!bms_is_empty(phv->phrels));
- ChangeVarNodes((Node *) phv->phexpr, relid, subst, 0);
+ ChangeVarNodesExtended((Node *) phv->phexpr, relid, subst, 0,
+ replace_relid_callback);
Assert(phv->phnullingrels == NULL); /* no need to adjust */
}
}
if (subst > 0)
- ChangeVarNodes((Node *) otherrel->lateral_vars, relid, subst, 0);
+ ChangeVarNodesExtended((Node *) otherrel->lateral_vars, relid,
+ subst, 0, replace_relid_callback);
}
}
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
if (sjinfo == NULL)
- ChangeVarNodes((Node *) rinfo, relid, subst, 0);
+ ChangeVarNodesExtended((Node *) rinfo, relid, subst, 0,
+ replace_relid_callback);
else
remove_rel_from_restrictinfo(rinfo, relid, sjinfo->ojrelid);
}
em->em_jdomain->jd_relids = adjust_relid_set(em->em_jdomain->jd_relids, from, to);
/* We only process inner joins */
- ChangeVarNodes((Node *) em->em_expr, from, to, 0);
+ ChangeVarNodesExtended((Node *) em->em_expr, from, to, 0,
+ replace_relid_callback);
foreach_node(EquivalenceMember, other, new_members)
{
continue;
}
- ChangeVarNodes((Node *) rinfo, from, to, 0);
+ ChangeVarNodesExtended((Node *) rinfo, from, to, 0,
+ replace_relid_callback);
/*
* After switching the clause to the remaining relation, check it for
}
}
+/*
+ * A custom callback for ChangeVarNodesExtended() providing
+ * Self-join elimination (SJE) related functionality
+ *
+ * SJE needs to skip the RangeTblRef node
+ * type. During SJE's last step, remove_rel_from_joinlist() removes
+ * remaining RangeTblRefs with target relid. If ChangeVarNodes() replaces
+ * the target relid before, remove_rel_from_joinlist() fails to identify
+ * the nodes to delete.
+ *
+ * SJE also needs to change the relids within RestrictInfo's.
+ */
+static bool
+replace_relid_callback(Node *node, ChangeVarNodes_context *context)
+{
+ if (IsA(node, RangeTblRef))
+ {
+ return true;
+ }
+ else if (IsA(node, RestrictInfo))
+ {
+ RestrictInfo *rinfo = (RestrictInfo *) node;
+ int relid = -1;
+ bool is_req_equal =
+ (rinfo->required_relids == rinfo->clause_relids);
+ bool clause_relids_is_multiple =
+ (bms_membership(rinfo->clause_relids) == BMS_MULTIPLE);
+
+ /*
+ * Recurse down into clauses if the target relation is present in
+ * clause_relids or required_relids. We must check required_relids
+ * because the relation not present in clause_relids might still be
+ * present somewhere in orclause.
+ */
+ if (bms_is_member(context->rt_index, rinfo->clause_relids) ||
+ bms_is_member(context->rt_index, rinfo->required_relids))
+ {
+ Relids new_clause_relids;
+
+ ChangeVarNodesWalkExpression((Node *) rinfo->clause, context);
+ ChangeVarNodesWalkExpression((Node *) rinfo->orclause, context);
+
+ new_clause_relids = adjust_relid_set(rinfo->clause_relids,
+ context->rt_index,
+ context->new_index);
+
+ /*
+ * Incrementally adjust num_base_rels based on the change of
+ * clause_relids, which could contain both base relids and
+ * outer-join relids. This operation is legal until we remove
+ * only baserels.
+ */
+ rinfo->num_base_rels -= bms_num_members(rinfo->clause_relids) -
+ bms_num_members(new_clause_relids);
+
+ rinfo->clause_relids = new_clause_relids;
+ rinfo->left_relids =
+ adjust_relid_set(rinfo->left_relids, context->rt_index, context->new_index);
+ rinfo->right_relids =
+ adjust_relid_set(rinfo->right_relids, context->rt_index, context->new_index);
+ }
+
+ if (is_req_equal)
+ rinfo->required_relids = rinfo->clause_relids;
+ else
+ rinfo->required_relids =
+ adjust_relid_set(rinfo->required_relids, context->rt_index, context->new_index);
+
+ rinfo->outer_relids =
+ adjust_relid_set(rinfo->outer_relids, context->rt_index, context->new_index);
+ rinfo->incompatible_relids =
+ adjust_relid_set(rinfo->incompatible_relids, context->rt_index, context->new_index);
+
+ if (rinfo->mergeopfamilies &&
+ bms_get_singleton_member(rinfo->clause_relids, &relid) &&
+ clause_relids_is_multiple &&
+ relid == context->new_index && IsA(rinfo->clause, OpExpr))
+ {
+ Expr *leftOp;
+ Expr *rightOp;
+
+ leftOp = (Expr *) get_leftop(rinfo->clause);
+ rightOp = (Expr *) get_rightop(rinfo->clause);
+
+ /*
+ * For self-join elimination, changing varnos could transform
+ * "t1.a = t2.a" into "t1.a = t1.a". That is always true as long
+ * as "t1.a" is not null. We use qual() to check for such a case,
+ * and then we replace the qual for a check for not null
+ * (NullTest).
+ */
+ if (leftOp != NULL && equal(leftOp, rightOp))
+ {
+ NullTest *ntest = makeNode(NullTest);
+
+ ntest->arg = leftOp;
+ ntest->nulltesttype = IS_NOT_NULL;
+ ntest->argisrow = false;
+ ntest->location = -1;
+ rinfo->clause = (Expr *) ntest;
+ rinfo->mergeopfamilies = NIL;
+ rinfo->left_em = NULL;
+ rinfo->right_em = NULL;
+ }
+ Assert(rinfo->orclause == NULL);
+ }
+ return true;
+ }
+
+ return false;
+}
+
/*
* Remove a relation after we have proven that it participates only in an
* unneeded unique self-join.
foreach_node(RestrictInfo, rinfo, joininfos)
{
remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
- ChangeVarNodes((Node *) rinfo, toRemove->relid, toKeep->relid, 0);
+ ChangeVarNodesExtended((Node *) rinfo, toRemove->relid, toKeep->relid,
+ 0, replace_relid_callback);
if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
jinfo_candidates = lappend(jinfo_candidates, rinfo);
restrictlist);
foreach_node(RestrictInfo, rinfo, toRemove->baserestrictinfo)
{
- ChangeVarNodes((Node *) rinfo, toRemove->relid, toKeep->relid, 0);
+ ChangeVarNodesExtended((Node *) rinfo, toRemove->relid, toKeep->relid,
+ 0, replace_relid_callback);
if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
jinfo_candidates = lappend(jinfo_candidates, rinfo);
{
Node *node = lfirst(lc);
- ChangeVarNodes(node, toRemove->relid, toKeep->relid, 0);
+ ChangeVarNodesExtended(node, toRemove->relid, toKeep->relid, 0,
+ replace_relid_callback);
if (!list_member(toKeep->reltarget->exprs, node))
toKeep->reltarget->exprs = lappend(toKeep->reltarget->exprs, node);
}
* Replace varno in all the query structures, except nodes RangeTblRef
* otherwise later remove_rel_from_joinlist will yield errors.
*/
- ChangeVarNodesExtended((Node *) root->parse, toRemove->relid, toKeep->relid, 0, false);
+ ChangeVarNodesExtended((Node *) root->parse, toRemove->relid, toKeep->relid,
+ 0, replace_relid_callback);
/* Replace links in the planner info */
remove_rel_from_query(root, toRemove, toKeep->relid, NULL, NULL);
/* At last, replace varno in root targetlist and HAVING clause */
- ChangeVarNodes((Node *) root->processed_tlist, toRemove->relid, toKeep->relid, 0);
- ChangeVarNodes((Node *) root->processed_groupClause, toRemove->relid, toKeep->relid, 0);
+ ChangeVarNodesExtended((Node *) root->processed_tlist, toRemove->relid,
+ toKeep->relid, 0, replace_relid_callback);
+ ChangeVarNodesExtended((Node *) root->processed_groupClause,
+ toRemove->relid, toKeep->relid, 0,
+ replace_relid_callback);
adjust_relid_set(root->all_result_relids, toRemove->relid, toKeep->relid);
adjust_relid_set(root->leaf_result_relids, toRemove->relid, toKeep->relid);
* when we have cast of the same var to different (but compatible)
* types.
*/
- ChangeVarNodes(rightexpr, bms_singleton_member(rinfo->right_relids),
- bms_singleton_member(rinfo->left_relids), 0);
+ ChangeVarNodesExtended(rightexpr,
+ bms_singleton_member(rinfo->right_relids),
+ bms_singleton_member(rinfo->left_relids), 0,
+ replace_relid_callback);
if (equal(leftexpr, rightexpr))
sjoinquals = lappend(sjoinquals, rinfo);
bms_is_empty(rinfo->right_relids));
clause = (Expr *) copyObject(rinfo->clause);
- ChangeVarNodes((Node *) clause, relid, outer->relid, 0);
+ ChangeVarNodesExtended((Node *) clause, relid, outer->relid, 0,
+ replace_relid_callback);
iclause = bms_is_empty(rinfo->left_relids) ? get_rightop(clause) :
get_leftop(clause);
* earlier to ensure that no unwanted side-effects occur!
*/
-typedef struct
-{
- int rt_index;
- int new_index;
- int sublevels_up;
- bool change_RangeTblRef;
-} ChangeVarNodes_context;
-
static bool
ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
{
if (node == NULL)
return false;
+
+ if (context->callback && context->callback(node, context))
+ return false;
+
if (IsA(node, Var))
{
Var *var = (Var *) node;
cexpr->cvarno = context->new_index;
return false;
}
- if (IsA(node, RangeTblRef) && context->change_RangeTblRef)
+ if (IsA(node, RangeTblRef))
{
RangeTblRef *rtr = (RangeTblRef *) node;
}
return false;
}
- if (IsA(node, RestrictInfo))
- {
- RestrictInfo *rinfo = (RestrictInfo *) node;
- int relid = -1;
- bool is_req_equal =
- (rinfo->required_relids == rinfo->clause_relids);
- bool clause_relids_is_multiple =
- (bms_membership(rinfo->clause_relids) == BMS_MULTIPLE);
-
- /*
- * Recurse down into clauses if the target relation is present in
- * clause_relids or required_relids. We must check required_relids
- * because the relation not present in clause_relids might still be
- * present somewhere in orclause.
- */
- if (bms_is_member(context->rt_index, rinfo->clause_relids) ||
- bms_is_member(context->rt_index, rinfo->required_relids))
- {
- Relids new_clause_relids;
-
- expression_tree_walker((Node *) rinfo->clause, ChangeVarNodes_walker, (void *) context);
- expression_tree_walker((Node *) rinfo->orclause, ChangeVarNodes_walker, (void *) context);
-
- new_clause_relids = adjust_relid_set(rinfo->clause_relids,
- context->rt_index,
- context->new_index);
-
- /*
- * Incrementally adjust num_base_rels based on the change of
- * clause_relids, which could contain both base relids and
- * outer-join relids. This operation is legal until we remove
- * only baserels.
- */
- rinfo->num_base_rels -= bms_num_members(rinfo->clause_relids) -
- bms_num_members(new_clause_relids);
-
- rinfo->clause_relids = new_clause_relids;
- rinfo->left_relids =
- adjust_relid_set(rinfo->left_relids, context->rt_index, context->new_index);
- rinfo->right_relids =
- adjust_relid_set(rinfo->right_relids, context->rt_index, context->new_index);
- }
-
- if (is_req_equal)
- rinfo->required_relids = rinfo->clause_relids;
- else
- rinfo->required_relids =
- adjust_relid_set(rinfo->required_relids, context->rt_index, context->new_index);
-
- rinfo->outer_relids =
- adjust_relid_set(rinfo->outer_relids, context->rt_index, context->new_index);
- rinfo->incompatible_relids =
- adjust_relid_set(rinfo->incompatible_relids, context->rt_index, context->new_index);
-
- if (rinfo->mergeopfamilies &&
- bms_get_singleton_member(rinfo->clause_relids, &relid) &&
- clause_relids_is_multiple &&
- relid == context->new_index && IsA(rinfo->clause, OpExpr))
- {
- Expr *leftOp;
- Expr *rightOp;
-
- leftOp = (Expr *) get_leftop(rinfo->clause);
- rightOp = (Expr *) get_rightop(rinfo->clause);
-
- /*
- * For self-join elimination, changing varnos could transform
- * "t1.a = t2.a" into "t1.a = t1.a". That is always true as long
- * as "t1.a" is not null. We use qual() to check for such a case,
- * and then we replace the qual for a check for not null
- * (NullTest).
- */
- if (leftOp != NULL && equal(leftOp, rightOp))
- {
- NullTest *ntest = makeNode(NullTest);
-
- ntest->arg = leftOp;
- ntest->nulltesttype = IS_NOT_NULL;
- ntest->argisrow = false;
- ntest->location = -1;
- rinfo->clause = (Expr *) ntest;
- rinfo->mergeopfamilies = NIL;
- rinfo->left_em = NULL;
- rinfo->right_em = NULL;
- }
- Assert(rinfo->orclause == NULL);
- }
- return false;
- }
if (IsA(node, AppendRelInfo))
{
AppendRelInfo *appinfo = (AppendRelInfo *) node;
}
/*
- * ChangeVarNodesExtended - similar to ChangeVarNodes, but has additional
- * 'change_RangeTblRef' param
+ * ChangeVarNodesExtended - similar to ChangeVarNodes, but with an additional
+ * 'callback' param
*
* ChangeVarNodes changes a given node and all of its underlying nodes.
- * However, self-join elimination (SJE) needs to skip the RangeTblRef node
- * type. During SJE's last step, remove_rel_from_joinlist() removes
- * remaining RangeTblRefs with target relid. If ChangeVarNodes() replaces
- * the target relid before, remove_rel_from_joinlist() fails to identify
- * the nodes to delete.
+ * This version of function additionally takes a callback, which has a
+ * chance to process a node before ChangeVarNodes_walker. A callback
+ * returns a boolean value indicating if given node should be skipped from
+ * further processing by ChangeVarNodes_walker. The callback is called
+ * only for expressions and other children nodes of a Query processed by
+ * a walker. Initial processing of the root Query doesn't involve the
+ * callback.
*/
void
ChangeVarNodesExtended(Node *node, int rt_index, int new_index,
- int sublevels_up, bool change_RangeTblRef)
+ int sublevels_up, ChangeVarNodes_callback callback)
{
ChangeVarNodes_context context;
context.rt_index = rt_index;
context.new_index = new_index;
context.sublevels_up = sublevels_up;
- context.change_RangeTblRef = change_RangeTblRef;
+ context.callback = callback;
/*
* Must be prepared to start with a Query or a bare expression tree; if
void
ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
{
- ChangeVarNodesExtended(node, rt_index, new_index, sublevels_up, true);
+ ChangeVarNodesExtended(node, rt_index, new_index, sublevels_up, NULL);
+}
+
+/*
+ * ChangeVarNodesWalkExpression - process expression within the custom
+ * callback provided to the
+ * ChangeVarNodesExtended.
+ */
+bool
+ChangeVarNodesWalkExpression(Node *node, ChangeVarNodes_context *context)
+{
+ return expression_tree_walker(node,
+ ChangeVarNodes_walker,
+ (void *) context);
}
/*
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