diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 41 |
1 files changed, 36 insertions, 5 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index 6bad18e77c7..7a8e2fd2b87 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -442,6 +442,19 @@ typedef struct PlannerInfo * fdwroutine - function hooks for FDW, if foreign table (else NULL) * fdw_private - private state for FDW, if foreign table (else NULL) * + * Two fields are used to cache knowledge acquired during the join search + * about whether this rel is provably unique when being joined to given other + * relation(s), ie, it can have at most one row matching any given row from + * that join relation. Currently we only attempt such proofs, and thus only + * populate these fields, for base rels; but someday they might be used for + * join rels too: + * + * unique_for_rels - list of Relid sets, each one being a set of other + * rels for which this one has been proven unique + * non_unique_for_rels - list of Relid sets, each one being a set of + * other rels for which we have tried and failed to prove + * this one unique + * * The presence of the remaining fields depends on the restrictions * and joins that the relation participates in: * @@ -562,6 +575,10 @@ typedef struct RelOptInfo struct FdwRoutine *fdwroutine; void *fdw_private; + /* cache space for remembering if we have proven this relation unique */ + List *unique_for_rels; /* known unique for these other relid set(s) */ + List *non_unique_for_rels; /* known not unique for these set(s) */ + /* used by various scans and joins: */ List *baserestrictinfo; /* RestrictInfo structures (if base * rel) */ @@ -572,8 +589,8 @@ typedef struct RelOptInfo * involving this rel */ bool has_eclass_joins; /* T means joininfo is incomplete */ - /* used by "other" relations. */ - Relids top_parent_relids; /* Relids of topmost parents. */ + /* used by "other" relations */ + Relids top_parent_relids; /* Relids of topmost parents */ } RelOptInfo; /* @@ -1272,6 +1289,9 @@ typedef struct JoinPath JoinType jointype; + bool inner_unique; /* each outer tuple provably matches no more + * than one inner tuple */ + Path *outerjoinpath; /* path for the outer side of the join */ Path *innerjoinpath; /* path for the inner side of the join */ @@ -1314,6 +1334,13 @@ typedef JoinPath NestPath; * mergejoin. If it is not NIL then it is a PathKeys list describing * the ordering that must be created by an explicit Sort node. * + * skip_mark_restore is TRUE if the executor need not do mark/restore calls. + * Mark/restore overhead is usually required, but can be skipped if we know + * that the executor need find only one match per outer tuple, and that the + * mergeclauses are sufficient to identify a match. In such cases the + * executor can immediately advance the outer relation after processing a + * match, and therefoere it need never back up the inner relation. + * * materialize_inner is TRUE if a Material node should be placed atop the * inner input. This may appear with or without an inner Sort step. */ @@ -1324,6 +1351,7 @@ typedef struct MergePath List *path_mergeclauses; /* join clauses to be used for merge */ List *outersortkeys; /* keys for explicit sort, if any */ List *innersortkeys; /* keys for explicit sort, if any */ + bool skip_mark_restore; /* can executor skip mark/restore? */ bool materialize_inner; /* add Materialize to inner? */ } MergePath; @@ -2112,8 +2140,8 @@ typedef struct PlannerParamItem } PlannerParamItem; /* - * When making cost estimates for a SEMI or ANTI join, there are some - * correction factors that are needed in both nestloop and hash joins + * When making cost estimates for a SEMI/ANTI/inner_unique join, there are + * some correction factors that are needed in both nestloop and hash joins * to account for the fact that the executor can stop scanning inner rows * as soon as it finds a match to the current outer row. These numbers * depend only on the selected outer and inner join relations, not on the @@ -2140,14 +2168,17 @@ typedef struct SemiAntiJoinFactors * clauses that apply to this join * mergeclause_list is a list of RestrictInfo nodes for available * mergejoin clauses in this join + * inner_unique is true if each outer tuple provably matches no more + * than one inner tuple * sjinfo is extra info about special joins for selectivity estimation - * semifactors is as shown above (only valid for SEMI or ANTI joins) + * semifactors is as shown above (only valid for SEMI/ANTI/inner_unique joins) * param_source_rels are OK targets for parameterization of result paths */ typedef struct JoinPathExtraData { List *restrictlist; List *mergeclause_list; + bool inner_unique; SpecialJoinInfo *sjinfo; SemiAntiJoinFactors semifactors; Relids param_source_rels; |