* Definitions for planner's internal data structures.
*
*
- * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $Id: relation.h,v 1.75 2003/01/12 22:35:29 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.95 2004/06/01 03:03:05 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#define RELATION_H
#include "access/sdir.h"
+#include "nodes/bitmapset.h"
#include "nodes/parsenodes.h"
+
/*
* Relids
- * List of relation identifiers (indexes into the rangetable).
- *
- * Note: these are lists of integers, not Nodes.
+ * Set of relation identifiers (indexes into the rangetable).
*/
-typedef List *Relids;
+typedef Bitmapset *Relids;
/*
* When looking for a "cheapest path", this enum specifies whether we want
* Per-relation information for planning/optimization
*
* For planning purposes, a "base rel" is either a plain relation (a table)
- * or the output of a sub-SELECT that appears in the range table.
+ * or the output of a sub-SELECT or function that appears in the range table.
* In either case it is uniquely identified by an RT index. A "joinrel"
* is the joining of two or more base rels. A joinrel is identified by
* the set of RT indexes for its component baserels. We create RelOptInfo
*
* We also have "other rels", which are like base rels in that they refer to
* single RT indexes; but they are not part of the join tree, and are stored
- * in other_rel_list not base_rel_list. An otherrel is created for each
- * join RTE as an aid in processing Vars that refer to the join's outputs,
- * but it serves no other purpose in planning. It is important not to
- * confuse this otherrel with the joinrel that represents the matching set
- * of base relations.
- *
- * A second category of otherrels are those made for child relations of an
- * inheritance scan (SELECT FROM foo*). The parent table's RTE and
+ * in other_rel_list not base_rel_list.
+ *
+ * Currently the only kind of otherrels are those made for child relations
+ * of an inheritance scan (SELECT FROM foo*). The parent table's RTE and
* corresponding baserel represent the whole result of the inheritance scan.
* The planner creates separate RTEs and associated RelOptInfos for each child
* table (including the parent table, in its capacity as a member of the
* the inheritance set; then the parent baserel is given an Append plan
* comprising the best plans for the individual child tables.
*
+ * 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
+ * alias Vars are expanded to non-aliased form during preprocess_expression.
+ *
* Parts of this data structure are specific to various scan and join
* mechanisms. It didn't seem worth creating new node types for them.
*
- * relids - List of base-relation identifiers; it is a base relation
+ * relids - Set of base-relation identifiers; it is a base relation
* if there is just one, a join relation if more than one
* rows - estimated number of tuples in the relation after restriction
* clauses have been applied (ie, output rows of a plan for it)
* width - avg. number of bytes per tuple in the relation after the
* appropriate projections have been done (ie, output width)
- * targetlist - List of TargetEntry nodes for the attributes we need
- * to output from this relation
+ * reltargetlist - List of Var nodes for the attributes we need to
+ * output from this relation (in no particular order)
* pathlist - List of Path nodes, one for each potentially useful
* method of generating the relation
* cheapest_startup_path - the pathlist member with lowest startup cost
* (regardless of its ordering)
* cheapest_total_path - the pathlist member with lowest total cost
* (regardless of its ordering)
- * pruneable - flag to let the planner know whether it can prune the
- * pathlist of this RelOptInfo or not.
+ * cheapest_unique_path - for caching cheapest path to produce unique
+ * (no duplicates) output from relation
*
* If the relation is a base relation it will have these fields set:
*
+ * relid - RTE index (this is redundant with the relids field, but
+ * is provided for convenience of access)
* rtekind - distinguishes plain relation, subquery, or function RTE
+ * min_attr, max_attr - range of valid AttrNumbers for rel
+ * attr_needed - array of bitmapsets indicating the highest joinrel
+ * in which each attribute is needed; if bit 0 is set then
+ * the attribute is needed as part of final targetlist
+ * attr_widths - cache space for per-attribute width estimates;
+ * zero means not computed yet
* indexlist - list of IndexOptInfo nodes for relation's indexes
* (always NIL if it's not a table)
* pages - number of disk pages in relation (zero if not a table)
* set_base_rel_pathlist processes the object.
*
* For otherrels that are inheritance children, these fields are filled
- * in just as for a baserel. In otherrels for join RTEs, these fields
- * are empty --- the only useful field of a join otherrel is its
- * outerjoinset.
- *
- * If the relation is a join relation it will have these fields set:
- *
- * joinrti - RT index of corresponding JOIN RTE, if any; 0 if none
- * joinrteids - List of RT indexes of JOIN RTEs included in this join
- * (including joinrti)
+ * in just as for a baserel.
*
* The presence of the remaining fields depends on the restrictions
* and joins that the relation participates in:
* baserestrictcost - Estimated cost of evaluating the baserestrictinfo
* clauses at a single tuple (only used for base rels)
* outerjoinset - For a base rel: if the rel appears within the nullable
- * side of an outer join, the list of all relids
- * participating in the highest such outer join; else NIL.
- * For a join otherrel: the list of all baserel relids
- * syntactically within the join. Otherwise, unused.
+ * side of an outer join, the set of all relids
+ * participating in the highest such outer join; else NULL.
+ * Otherwise, unused.
* joininfo - List of JoinInfo nodes, containing info about each join
* clause in which this relation participates
- * index_outer_relids - only used for base rels; list of outer relids
+ * index_outer_relids - only used for base rels; set of outer relids
* that participate in indexable joinclauses for this rel
* index_inner_paths - only used for base rels; list of InnerIndexscanInfo
* nodes showing best indexpaths for various subsets of
{
RELOPT_BASEREL,
RELOPT_JOINREL,
- RELOPT_OTHER_JOIN_REL,
RELOPT_OTHER_CHILD_REL
} RelOptKind;
RelOptKind reloptkind;
/* all relations included in this RelOptInfo */
- Relids relids; /* integer list of base relids (rangetable
- * indexes) */
+ Relids relids; /* set of base relids (rangetable indexes) */
/* size estimates generated by planner */
double rows; /* estimated number of result tuples */
int width; /* estimated avg width of result tuples */
/* materialization information */
- List *targetlist;
+ List *reltargetlist; /* needed Vars */
List *pathlist; /* Path structures */
struct Path *cheapest_startup_path;
struct Path *cheapest_total_path;
- bool pruneable;
+ struct Path *cheapest_unique_path;
/* information about a base rel (not set for join rels!) */
+ Index relid;
RTEKind rtekind; /* RELATION, SUBQUERY, or FUNCTION */
+ AttrNumber min_attr; /* smallest attrno of rel (often <0) */
+ AttrNumber max_attr; /* largest attrno of rel */
+ Relids *attr_needed; /* array indexed [min_attr .. max_attr] */
+ int32 *attr_widths; /* array indexed [min_attr .. max_attr] */
List *indexlist;
long pages;
double tuples;
struct Plan *subplan; /* if subquery */
- /* information about a join rel (not set for base rels!) */
- Index joinrti;
- List *joinrteids;
-
/* used by various scans and joins: */
List *baserestrictinfo; /* RestrictInfo structures (if
* base rel) */
QualCost baserestrictcost; /* cost of evaluating the above */
- Relids outerjoinset; /* integer list of base relids */
+ Relids outerjoinset; /* set of base relids */
List *joininfo; /* JoinInfo structures */
/* cached info about inner indexscan paths for relation: */
Relids index_outer_relids; /* other relids in indexable join
* clauses */
List *index_inner_paths; /* InnerIndexscanInfo nodes */
+
/*
- * Inner indexscans are not in the main pathlist because they are
- * not usable except in specific join contexts. We use the
+ * Inner indexscans are not in the main pathlist because they are not
+ * usable except in specific join contexts. We use the
* index_inner_paths list just to avoid recomputing the best inner
- * indexscan repeatedly for similar outer relations. See comments
- * for InnerIndexscanInfo.
+ * indexscan repeatedly for similar outer relations. See comments for
+ * InnerIndexscanInfo.
*/
} RelOptInfo;
* and indexes, but that created confusion without actually doing anything
* useful. So now we have a separate IndexOptInfo struct for indexes.
*
- * ncolumns and nkeys are the same except for a functional index,
- * wherein ncolumns is 1 (the single function output) while nkeys
- * is the number of table columns passed to the function. classlist[]
- * and ordering[] have ncolumns entries, while indexkeys[] has nkeys
- * entries.
+ * classlist[], indexkeys[], and ordering[] have ncolumns entries.
+ * Zeroes in the indexkeys[] array indicate index columns that are
+ * expressions; there is one element in indexprs for each such column.
+ *
+ * Note: for historical reasons, the classlist and ordering arrays have
+ * an extra entry that is always zero. Some code scans until it sees a
+ * zero entry, rather than looking at ncolumns.
*
- * Note: for historical reasons, the arrays classlist, indexkeys and
- * ordering have an extra entry that is always zero. Some code scans
- * until it sees a zero rather than looking at ncolumns or nkeys.
+ * The indexprs and indpred expressions have been run through
+ * prepqual.c and eval_const_expressions() for ease of matching to
+ * WHERE clauses. indpred is in implicit-AND form.
*/
typedef struct IndexOptInfo
/* index descriptor information */
int ncolumns; /* number of columns in index */
- int nkeys; /* number of keys used by index */
Oid *classlist; /* OIDs of operator classes for columns */
- int *indexkeys; /* column numbers of index's keys */
+ int *indexkeys; /* column numbers of index's keys, or 0 */
Oid *ordering; /* OIDs of sort operators for each column */
Oid relam; /* OID of the access method (in pg_am) */
RegProcedure amcostestimate; /* OID of the access method's cost fcn */
- Oid indproc; /* OID of func if functional index, else 0 */
+ List *indexprs; /* expressions for non-simple index
+ * columns */
List *indpred; /* predicate if a partial index, else NIL */
+
+ bool predOK; /* true if predicate matches query */
bool unique; /* true if a unique index */
/* cached info about inner indexscan paths for index */
} IndexOptInfo;
-/*
- * A Var is considered to belong to a relation if it's either from one
- * of the actual base rels making up the relation, or it's a join alias
- * var that is included in the relation.
- */
-#define VARISRELMEMBER(varno,rel) (intMember((varno), (rel)->relids) || \
- intMember((varno), (rel)->joinrteids))
-
-
/*
* PathKeys
*
/*
* key typically points to a Var node, ie a relation attribute, but it
- * can also point to a FuncExpr clause representing the value indexed by a
- * functional index. Someday we might allow arbitrary expressions as
- * path keys, so don't assume more than you must.
+ * can also point to an arbitrary expression representing the value
+ * indexed by an index expression.
*/
} PathKeyItem;
{
NodeTag type;
+ NodeTag pathtype; /* tag identifying scan/join method */
+
RelOptInfo *parent; /* the relation this path can build */
/* estimated execution costs for path (see costsize.c for more info) */
Cost total_cost; /* total cost (assuming all tuples
* fetched) */
- NodeTag pathtype; /* tag identifying scan/join method */
-
List *pathkeys; /* sort ordering of path's output */
/* pathkeys is a List of Lists of PathKeyItem nodes; see above */
} Path;
*
* 'indexinfo' is a list of IndexOptInfo nodes, one per scan to be performed.
*
- * 'indexqual' is a list of index qualifications, also one per scan.
- * Each entry in 'indexqual' is a sublist of qualification expressions with
- * implicit AND semantics across the sublist items. Only expressions that
- * are usable as indexquals (as determined by indxpath.c) may appear here.
- * NOTE that the semantics of the top-level list in 'indexqual' is OR
+ * 'indexclauses' is a list of index qualifications, also one per scan.
+ * Each entry in 'indexclauses' is a sublist of qualification clauses to be
+ * used for that scan, with implicit AND semantics across the sublist items.
+ * NOTE that the semantics of the top-level list in 'indexclauses' is OR
* combination, while the sublists are implicitly AND combinations!
- * Also note that indexquals lists do not contain RestrictInfo nodes,
- * just bare clause expressions.
+ *
+ * 'indexquals' has the same structure as 'indexclauses', but it contains
+ * the actual indexqual conditions that can be used with the index(es).
+ * In simple cases this is identical to 'indexclauses', but when special
+ * indexable operators appear in 'indexclauses', they are replaced by the
+ * derived indexscannable conditions in 'indexquals'.
+ *
+ * Both 'indexclauses' and 'indexquals' are lists of sublists of RestrictInfo
+ * nodes. (Before 7.5, we kept bare operator expressions in these lists, but
+ * storing RestrictInfos is more efficient since selectivities can be cached.)
+ *
+ * 'isjoininner' is TRUE if the path is a nestloop inner scan (that is,
+ * some of the index conditions are join rather than restriction clauses).
*
* 'indexscandir' is one of:
* ForwardScanDirection: forward scan of an ordered index
{
Path path;
List *indexinfo;
- List *indexqual;
+ List *indexclauses;
+ List *indexquals;
+ bool isjoininner;
ScanDirection indexscandir;
double rows; /* estimated number of result tuples */
} IndexPath;
/*
* TidPath represents a scan by TID
+ *
+ * tideval is an implicitly OR'ed list of quals of the form CTID = something.
+ * Note they are bare quals, not RestrictInfos.
*/
typedef struct TidPath
{
* variable-free targetlist or to gate execution of a subplan with a
* one-time (variable-free) qual condition. Note that in the former case
* path.parent will be NULL; in the latter case it is copied from the subpath.
+ *
+ * Note that constantqual is a list of bare clauses, not RestrictInfos.
*/
typedef struct ResultPath
{
Path *subpath;
} MaterialPath;
+/*
+ * UniquePath represents elimination of distinct rows from the output of
+ * its subpath.
+ *
+ * This is unlike the other Path nodes in that it can actually generate
+ * different plans: either hash-based or sort-based implementation, or a
+ * no-op if the input path can be proven distinct already. The decision
+ * is sufficiently localized that it's not worth having separate Path node
+ * types. (Note: in the no-op case, we could eliminate the UniquePath node
+ * entirely and just return the subpath; but it's convenient to have a
+ * UniquePath in the path tree to signal upper-level routines that the input
+ * is known distinct.)
+ */
+typedef enum
+{
+ UNIQUE_PATH_NOOP, /* input is known unique already */
+ UNIQUE_PATH_HASH, /* use hashing */
+ UNIQUE_PATH_SORT /* use sorting */
+} UniquePathMethod;
+
+typedef struct UniquePath
+{
+ Path path;
+ Path *subpath;
+ UniquePathMethod umethod;
+ double rows; /* estimated number of result tuples */
+} UniquePath;
+
/*
* All join-type paths share these fields.
*/
* A mergejoin path has these fields.
*
* path_mergeclauses lists the clauses (in the form of RestrictInfos)
- * that will be used in the merge. (Before 7.0, this was a list of bare
- * clause expressions, but we can save on list memory and cost_qual_eval
- * work by leaving it in the form of a RestrictInfo list.)
+ * that will be used in the merge.
*
* Note that the mergeclauses are a subset of the parent relation's
* restriction-clause list. Any join clauses that are not mergejoinable
* When we do form the outer join's joinrel, we still need to distinguish
* those quals that are actually in that join's JOIN/ON condition from those
* that appeared higher in the tree and were pushed down to the join rel
- * because they used no other rels. That's what the ispusheddown flag is for;
- * it tells us that a qual came from a point above the join of the specific
- * set of base rels that it uses (or that the JoinInfo structures claim it
- * uses). A clause that originally came from WHERE will *always* have its
- * ispusheddown flag set; a clause that came from an INNER JOIN condition,
- * but doesn't use all the rels being joined, will also have ispusheddown set
- * because it will get attached to some lower joinrel.
+ * because they used no other rels. That's what the is_pushed_down flag is
+ * for; it tells us that a qual came from a point above the join of the
+ * specific set of base rels that it uses (or that the JoinInfo structures
+ * claim it uses). A clause that originally came from WHERE will *always*
+ * have its is_pushed_down flag set; a clause that came from an INNER JOIN
+ * condition, but doesn't use all the rels being joined, will also have
+ * is_pushed_down set because it will get attached to some lower joinrel.
+ *
+ * We also store a valid_everywhere flag, which says that the clause is not
+ * affected by any lower-level outer join, and therefore any conditions it
+ * asserts can be presumed true throughout the plan tree.
*
* In general, the referenced clause might be arbitrarily complex. The
* kinds of clauses we can handle as indexscan quals, mergejoin clauses,
* qual-expression-evaluation code. (But we are still entitled to count
* their selectivity when estimating the result tuple count, if we
* can guess what it is...)
+ *
+ * When the referenced clause is an OR clause, we generate a modified copy
+ * in which additional RestrictInfo nodes are inserted below the top-level
+ * OR/AND structure. This is a convenience for OR indexscan processing:
+ * indexquals taken from either the top level or an OR subclause will have
+ * associated RestrictInfo nodes.
*/
typedef struct RestrictInfo
Expr *clause; /* the represented clause of WHERE or JOIN */
- bool ispusheddown; /* TRUE if clause was pushed down in level */
+ bool is_pushed_down; /* TRUE if clause was pushed down in level */
+
+ bool valid_everywhere; /* TRUE if valid on every level */
+
+ /*
+ * This flag is set true if the clause looks potentially useful as a
+ * merge or hash join clause, that is if it is a binary opclause with
+ * nonoverlapping sets of relids referenced in the left and right sides.
+ * (Whether the operator is actually merge or hash joinable isn't
+ * checked, however.)
+ */
+ bool can_join;
+
+ /* The set of relids (varnos) referenced in the clause: */
+ Relids clause_relids;
+
+ /* These fields are set for any binary opclause: */
+ Relids left_relids; /* relids in left side of clause */
+ Relids right_relids; /* relids in right side of clause */
- /* only used if clause is an OR clause: */
- List *subclauseindices; /* indexes matching subclauses */
- /* subclauseindices is a List of Lists of IndexOptInfos */
+ /* This field is NULL unless clause is an OR clause: */
+ Expr *orclause; /* modified clause with RestrictInfos */
- /* cache space for costs (currently only used for join clauses) */
+ /* cache space for cost and selectivity */
QualCost eval_cost; /* eval cost of clause; -1 if not yet set */
Selectivity this_selec; /* selectivity; -1 if not yet set */
* relation includes all other relids appearing in those joinclauses.
* The set of usable joinclauses, and thus the best inner indexscan,
* thus varies depending on which outer relation we consider; so we have
- * to recompute the best such path for every join. To avoid lots of
+ * to recompute the best such path for every join. To avoid lots of
* redundant computation, we cache the results of such searches. For
* each index we compute the set of possible otherrelids (all relids
* appearing in joinquals that could become indexquals for this index).
Relids other_relids; /* a set of relevant other relids */
bool isouterjoin; /* true if join is outer */
/* Best path for this lookup key: */
- Path *best_innerpath; /* best inner indexscan, or NULL if none */
+ Path *best_innerpath; /* best inner indexscan, or NULL if none */
} InnerIndexscanInfo;
+/*
+ * IN clause info.
+ *
+ * When we convert top-level IN quals into join operations, we must restrict
+ * the order of joining and use special join methods at some join points.
+ * We record information about each such IN clause in an InClauseInfo struct.
+ * These structs are kept in the Query node's in_info_list.
+ */
+
+typedef struct InClauseInfo
+{
+ NodeTag type;
+ Relids lefthand; /* base relids in lefthand expressions */
+ Relids righthand; /* base relids coming from the subselect */
+ List *sub_targetlist; /* targetlist of original RHS subquery */
+
+ /*
+ * Note: sub_targetlist is just a list of Vars or expressions; it does
+ * not contain TargetEntry nodes.
+ */
+} InClauseInfo;
+
#endif /* RELATION_H */
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