diff options
Diffstat (limited to 'src/include/nodes/relation.h')
| -rw-r--r-- | src/include/nodes/relation.h | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h index 75fb572de0f..4e285a765ad 100644 --- a/src/include/nodes/relation.h +++ b/src/include/nodes/relation.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.130 2007/01/05 22:19:56 momjian Exp $ + * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.131 2007/01/09 02:14:15 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -300,19 +300,23 @@ typedef struct RelOptInfo * and indexes, but that created confusion without actually doing anything * useful. So now we have a separate IndexOptInfo struct for indexes. * - * opfamily[], indexkeys[], and ordering[] have ncolumns entries. + * opfamily[], indexkeys[], fwdsortop[], revsortop[], and nulls_first[] + * each have ncolumns entries. Note: for historical reasons, the + * opfamily array has an extra entry that is always zero. Some code + * scans until it sees a zero entry, rather than looking at ncolumns. + * * 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 opfamily 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. + * For an unordered index, the sortop arrays contains zeroes. Note that + * fwdsortop[] and nulls_first[] describe the sort ordering of a forward + * indexscan; we can also consider a backward indexscan, which will + * generate sort order described by revsortop/!nulls_first. * * 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. + * WHERE clauses. indpred is in implicit-AND form. */ - typedef struct IndexOptInfo { NodeTag type; @@ -328,7 +332,9 @@ typedef struct IndexOptInfo int ncolumns; /* number of columns in index */ Oid *opfamily; /* OIDs of operator families for columns */ int *indexkeys; /* column numbers of index's keys, or 0 */ - Oid *ordering; /* OIDs of sort operators for each column */ + Oid *fwdsortop; /* OIDs of sort operators for each column */ + Oid *revsortop; /* OIDs of sort operators for backward scan */ + bool *nulls_first; /* do NULLs come first in the sort order? */ Oid relam; /* OID of the access method (in pg_am) */ RegProcedure amcostestimate; /* OID of the access method's cost fcn */ @@ -360,6 +366,7 @@ typedef struct PathKeyItem Node *key; /* the item that is ordered */ Oid sortop; /* the ordering operator ('<' op) */ + bool nulls_first; /* do NULLs come before normal values? */ /* * key typically points to a Var node, ie a relation attribute, but it can |