* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.88 2003/12/30 23:53:15 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.95 2004/06/01 03:03:05 tgl Exp $
*
*-------------------------------------------------------------------------
*/
* (regardless of its ordering)
* cheapest_unique_path - for caching cheapest path to produce unique
* (no duplicates) output from relation
- * pruneable - flag to let the planner know whether it can prune the
- * pathlist of this RelOptInfo or not.
*
* If the relation is a base relation it will have these fields set:
*
int width; /* estimated avg width of result tuples */
/* materialization information */
- FastList reltargetlist;
+ List *reltargetlist; /* needed Vars */
List *pathlist; /* Path structures */
struct Path *cheapest_startup_path;
struct Path *cheapest_total_path;
struct Path *cheapest_unique_path;
- bool pruneable;
/* information about a base rel (not set for join rels!) */
Index relid;
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 */
{
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.
- *
- * 'indexjoinclauses' is NIL for an ordinary indexpath (one that does not
- * use any join clauses in the index conditions). For an innerjoin indexpath,
- * it has the same structure as 'indexqual', but references the RestrictInfo
- * nodes from which the indexqual was built, rather than the bare clause
- * expressions. (Note: there isn't necessarily a one-to-one correspondence
- * between RestrictInfos and expressions, because of expansion of special
- * indexable operators.) We need this so that we can eliminate redundant
- * join clauses when plans are built.
+ *
+ * '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 *indexjoinclauses;
+ 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
{
* its subpath.
*
* This is unlike the other Path nodes in that it can actually generate
- * two different plans: either hash-based or sort-based implementation.
- * The decision is sufficiently localized that it's not worth having two
- * separate Path node types.
+ * 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;
- bool use_hash;
+ UniquePathMethod umethod;
double rows; /* estimated number of result tuples */
} UniquePath;
* 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
* (Whether the operator is actually merge or hash joinable isn't
* checked, however.)
*/
- bool canjoin;
+ 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 */
projects / postgresql / blobdiff