diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 101 |
1 files changed, 75 insertions, 26 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index e14f1ea4e83..d26d60c71be 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: relation.h,v 1.62 2002/03/01 06:01:20 tgl Exp $ + * $Id: relation.h,v 1.63 2002/03/12 00:52:02 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -39,18 +39,39 @@ typedef enum CostSelector * RelOptInfo * 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. - * 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. - * - * Note that there is only one joinrel for any given set of component - * baserels, no matter what order we assemble them in; so an unordered - * set is the right datatype to identify it with. - * - * Parts of this data structure are specific to various scan and join - * mechanisms. It didn't seem worth creating new node types for them. + * 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. + * 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 + * nodes for each baserel and joinrel, and store them in the Query's + * base_rel_list and join_rel_list respectively. + * + * Note that there is only one joinrel for any given set of component + * baserels, no matter what order we assemble them in; so an unordered + * set is the right datatype to identify it with. + * + * 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 + * 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 + * inheritance set). These RelOptInfos are physically identical to baserels, + * but are otherrels because they are not in the main join tree. These added + * RTEs and otherrels are used to plan the scans of the individual tables in + * the inheritance set; then the parent baserel is given an Append plan + * comprising the best plans for the individual child tables. + * + * 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 * if there is just one, a join relation if more than one @@ -69,7 +90,7 @@ typedef enum CostSelector * 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: + * If the relation is a base relation it will have these fields set: * * issubquery - true if baserel is a subquery RTE rather than a table * indexlist - list of IndexOptInfo nodes for relation's indexes @@ -82,25 +103,30 @@ typedef enum CostSelector * upon creation of the RelOptInfo object; they are filled in when * set_base_rel_pathlist processes the object. * - * Note: if a base relation is the root of an inheritance tree - * (SELECT FROM foo*) it is still considered a base rel. We will - * generate a list of candidate Paths for accessing that table itself, - * and also generate baserel RelOptInfo nodes for each child table, - * with their own candidate Path lists. Then, an AppendPath is built - * from the cheapest Path for each of these tables, and set to be the - * only available Path for the inheritance baserel. + * 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: * - * * The presence of the remaining fields depends on the restrictions - * and joins that the relation participates in: + * 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) + * + * The presence of the remaining fields depends on the restrictions + * and joins that the relation participates in: * * baserestrictinfo - List of RestrictInfo nodes, containing info about * each qualification clause in which this relation * participates (only used for base rels) * baserestrictcost - Estimated cost of evaluating the baserestrictinfo * clauses at a single tuple (only used for base rels) - * outerjoinset - 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 (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. * joininfo - List of JoinInfo nodes, containing info about each join * clause in which this relation participates * innerjoin - List of Path nodes that represent indices that may be used @@ -128,11 +154,20 @@ typedef enum CostSelector * until after the outer join is performed. *---------- */ +typedef enum RelOptKind +{ + RELOPT_BASEREL, + RELOPT_JOINREL, + RELOPT_OTHER_JOIN_REL, + RELOPT_OTHER_CHILD_REL +} RelOptKind; typedef struct RelOptInfo { NodeTag type; + RelOptKind reloptkind; + /* all relations included in this RelOptInfo */ Relids relids; /* integer list of base relids (RT * indexes) */ @@ -155,6 +190,10 @@ typedef struct RelOptInfo double tuples; struct Plan *subplan; + /* 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) */ @@ -228,6 +267,16 @@ typedef struct IndexOptInfo bool unique; /* if a unique 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 * |