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Indexes with INCLUDE columns and their support in B-tree
This patch introduces INCLUDE clause to index definition. This clause specifies a list of columns which will be included as a non-key part in the index. The INCLUDE columns exist solely to allow more queries to benefit from index-only scans. Also, such columns don't need to have appropriate operator classes. Expressions are not supported as INCLUDE columns since they cannot be used in index-only scans. Index access methods supporting INCLUDE are indicated by amcaninclude flag in IndexAmRoutine. For now, only B-tree indexes support INCLUDE clause. In B-tree indexes INCLUDE columns are truncated from pivot index tuples (tuples located in non-leaf pages and high keys). Therefore, B-tree indexes now might have variable number of attributes. This patch also provides generic facility to support that: pivot tuples contain number of their attributes in t_tid.ip_posid. Free 13th bit of t_info is used for indicating that. This facility will simplify further support of index suffix truncation. The changes of above are backward-compatible, pg_upgrade doesn't need special handling of B-tree indexes for that. Bump catalog version Author: Anastasia Lubennikova with contribition by Alexander Korotkov and me Reviewed by: Peter Geoghegan, Tomas Vondra, Antonin Houska, Jeff Janes, David Rowley, Alexander Korotkov Discussion: https://www.postgresql.org/message-id/flat/56168952.4010101@postgrespro.ru
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@ -2162,7 +2162,7 @@ match_eclass_clauses_to_index(PlannerInfo *root, IndexOptInfo *index,
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if (!index->rel->has_eclass_joins)
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return;
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for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
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for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
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{
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ec_member_matches_arg arg;
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List *clauses;
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@ -447,8 +447,10 @@ get_cheapest_parallel_safe_total_inner(List *paths)
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* If 'scandir' is BackwardScanDirection, build pathkeys representing a
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* backwards scan of the index.
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*
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* The result is canonical, meaning that redundant pathkeys are removed;
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* it may therefore have fewer entries than there are index columns.
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* We iterate only key columns of covering indexes, since non-key columns
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* don't influence index ordering. The result is canonical, meaning that
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* redundant pathkeys are removed; it may therefore have fewer entries than
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* there are key columns in the index.
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*
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* Another reason for stopping early is that we may be able to tell that
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* an index column's sort order is uninteresting for this query. However,
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@ -477,6 +479,13 @@ build_index_pathkeys(PlannerInfo *root,
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bool nulls_first;
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PathKey *cpathkey;
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/*
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* INCLUDE columns are stored in index unordered, so they don't
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* support ordered index scan.
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*/
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if (i >= index->nkeycolumns)
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break;
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/* We assume we don't need to make a copy of the tlist item */
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indexkey = indextle->expr;
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