* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.188 2010/07/12 17:01:06 tgl Exp $
+ * src/include/nodes/relation.h
*
*-------------------------------------------------------------------------
*/
List *distinct_pathkeys; /* distinctClause pathkeys, if any */
List *sort_pathkeys; /* sortClause pathkeys, if any */
+ List *minmax_aggs; /* List of MinMaxAggInfos */
+
List *initial_rels; /* RelOptInfos we are now trying to join */
MemoryContext planner_cxt; /* context holding PlannerInfo */
double total_table_pages; /* # of pages in all tables of query */
double tuple_fraction; /* tuple_fraction passed to query_planner */
+ double limit_tuples; /* limit_tuples passed to query_planner */
bool hasInheritedTarget; /* true if parse->resultRelation is an
* inheritance child rel */
* the entire append relation. The member RTEs are otherrels. The parent
* is present in the query join tree but the members are not. The member
* RTEs and otherrels are used to plan the scans of the individual tables or
- * subqueries of the append set; then the parent baserel is given an Append
- * plan comprising the best plans for the individual member rels. (See
- * comments for AppendRelInfo for more information.)
+ * subqueries of the append set; then the parent baserel is given Append
+ * and/or MergeAppend paths comprising the best paths for the individual
+ * member rels. (See comments for AppendRelInfo for more information.)
*
* At one time we also made otherrels to represent join RTEs, for use in
* handling join alias Vars. Currently this is not needed because all join
*
* opfamily[], indexkeys[], opcintype[], fwdsortop[], revsortop[],
* and nulls_first[] each have ncolumns entries.
- * Note: for historical reasons, the opfamily array has an extra entry
- * that is always zero. Some code scans until it sees a zero entry,
- * rather than looking at ncolumns.
*
* Zeroes in the indexkeys[] array indicate index columns that are
* expressions; there is one element in indexprs for each such column.
bool predOK; /* true if predicate matches query */
bool unique; /* true if a unique index */
+ bool amcanorderbyop; /* does AM support order by operator result? */
bool amoptionalkey; /* can query omit key for the first column? */
bool amsearchnulls; /* can AM search for NULL/NOT NULL entries? */
bool amhasgettuple; /* does AM have amgettuple interface? */
*
* em_is_child signifies that this element was built by transposing a member
* for an inheritance parent relation to represent the corresponding expression
- * on an inheritance child. The element should be ignored for all purposes
- * except constructing inner-indexscan paths for the child relation. (Other
- * types of join are driven from transposed joininfo-list entries.) Note
- * that the EC's ec_relids field does NOT include the child relation.
+ * on an inheritance child. These elements are used for constructing
+ * inner-indexscan paths for the child relation (other types of join are
+ * driven from transposed joininfo-list entries) and for constructing
+ * MergeAppend paths for the whole inheritance tree. Note that the EC's
+ * ec_relids field does NOT include the child relation.
*
* em_datatype is usually the same as exprType(em_expr), but can be
* different when dealing with a binary-compatible opfamily; in particular
#define IS_DUMMY_PATH(p) \
(IsA((p), AppendPath) && ((AppendPath *) (p))->subpaths == NIL)
+/*
+ * MergeAppendPath represents a MergeAppend plan, ie, the merging of sorted
+ * results from several member plans to produce similarly-sorted output.
+ */
+typedef struct MergeAppendPath
+{
+ Path path;
+ List *subpaths; /* list of component Paths */
+ double limit_tuples; /* hard limit on output tuples, or -1 */
+} MergeAppendPath;
+
/*
* ResultPath represents use of a Result plan node to compute a variable-free
* targetlist with no underlying tables (a "SELECT expressions" query).
* then allow it to bubble up like a Var until the ph_needed join level.
* ph_needed has the same definition as attr_needed for a regular Var.
*
+ * ph_may_need is an initial estimate of ph_needed, formed using the
+ * syntactic locations of references to the PHV. We need this in order to
+ * determine whether the PHV reference forces a join ordering constraint:
+ * if the PHV has to be evaluated below the nullable side of an outer join,
+ * and then used above that outer join, we must constrain join order to ensure
+ * there's a valid place to evaluate the PHV below the join. The final
+ * actual ph_needed level might be lower than ph_may_need, but we can't
+ * determine that until later on. Fortunately this doesn't matter for what
+ * we need ph_may_need for: if there's a PHV reference syntactically
+ * above the outer join, it's not going to be allowed to drop below the outer
+ * join, so we would come to the same conclusions about join order even if
+ * we had the final ph_needed value to compare to.
+ *
* We create a PlaceHolderInfo only after determining that the PlaceHolderVar
- * is actually referenced in the plan tree.
+ * is actually referenced in the plan tree, so that unreferenced placeholders
+ * don't result in unnecessary constraints on join order.
*/
typedef struct PlaceHolderInfo
PlaceHolderVar *ph_var; /* copy of PlaceHolderVar tree */
Relids ph_eval_at; /* lowest level we can evaluate value at */
Relids ph_needed; /* highest level the value is needed at */
+ Relids ph_may_need; /* highest level it might be needed at */
int32 ph_width; /* estimated attribute width */
} PlaceHolderInfo;
+/*
+ * For each potentially index-optimizable MIN/MAX aggregate function,
+ * root->minmax_aggs stores a MinMaxAggInfo describing it.
+ *
+ * Note: a MIN/MAX agg doesn't really care about the nulls_first property,
+ * so the pathkey's nulls_first flag should be ignored.
+ */
+typedef struct MinMaxAggInfo
+{
+ NodeTag type;
+
+ Oid aggfnoid; /* pg_proc Oid of the aggregate */
+ Oid aggsortop; /* Oid of its sort operator */
+ Expr *target; /* expression we are aggregating on */
+ List *pathkeys; /* pathkeys representing needed sort order */
+} MinMaxAggInfo;
+
/*
* glob->paramlist keeps track of the PARAM_EXEC slots that we have decided
* we need for the query. At runtime these slots are used to pass values
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