diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 40 |
1 files changed, 21 insertions, 19 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index 166f1242b0e..460679416f1 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -7,7 +7,7 @@ * 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 1.92 2004/01/05 18:04:39 tgl Exp $ + * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.93 2004/01/05 23:39:54 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -344,23 +344,24 @@ typedef struct 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 @@ -381,8 +382,9 @@ typedef struct IndexPath { Path path; List *indexinfo; - List *indexqual; - List *indexjoinclauses; + List *indexclauses; + List *indexquals; + bool isjoininner; ScanDirection indexscandir; double rows; /* estimated number of result tuples */ } IndexPath; |