7103ebb7aa
MERGE performs actions that modify rows in the target table using a source table or query. MERGE provides a single SQL statement that can conditionally INSERT/UPDATE/DELETE rows -- a task that would otherwise require multiple PL statements. For example, MERGE INTO target AS t USING source AS s ON t.tid = s.sid WHEN MATCHED AND t.balance > s.delta THEN UPDATE SET balance = t.balance - s.delta WHEN MATCHED THEN DELETE WHEN NOT MATCHED AND s.delta > 0 THEN INSERT VALUES (s.sid, s.delta) WHEN NOT MATCHED THEN DO NOTHING; MERGE works with regular tables, partitioned tables and inheritance hierarchies, including column and row security enforcement, as well as support for row and statement triggers and transition tables therein. MERGE is optimized for OLTP and is parameterizable, though also useful for large scale ETL/ELT. MERGE is not intended to be used in preference to existing single SQL commands for INSERT, UPDATE or DELETE since there is some overhead. MERGE can be used from PL/pgSQL. MERGE does not support targetting updatable views or foreign tables, and RETURNING clauses are not allowed either. These limitations are likely fixable with sufficient effort. Rewrite rules are also not supported, but it's not clear that we'd want to support them. Author: Pavan Deolasee <pavan.deolasee@gmail.com> Author: Álvaro Herrera <alvherre@alvh.no-ip.org> Author: Amit Langote <amitlangote09@gmail.com> Author: Simon Riggs <simon.riggs@enterprisedb.com> Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com> Reviewed-by: Andres Freund <andres@anarazel.de> (earlier versions) Reviewed-by: Peter Geoghegan <pg@bowt.ie> (earlier versions) Reviewed-by: Robert Haas <robertmhaas@gmail.com> (earlier versions) Reviewed-by: Japin Li <japinli@hotmail.com> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com> Reviewed-by: Zhihong Yu <zyu@yugabyte.com> Discussion: https://postgr.es/m/CANP8+jKitBSrB7oTgT9CY2i1ObfOt36z0XMraQc+Xrz8QB0nXA@mail.gmail.com Discussion: https://postgr.es/m/CAH2-WzkJdBuxj9PO=2QaO9-3h3xGbQPZ34kJH=HukRekwM-GZg@mail.gmail.com Discussion: https://postgr.es/m/20201231134736.GA25392@alvherre.pgsql
58 lines
1.6 KiB
C
58 lines
1.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* prep.h
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* prototypes for files in optimizer/prep/
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*
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*
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* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/optimizer/prep.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PREP_H
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#define PREP_H
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#include "nodes/pathnodes.h"
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#include "nodes/plannodes.h"
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/*
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* prototypes for prepjointree.c
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*/
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extern void transform_MERGE_to_join(Query *parse);
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extern void replace_empty_jointree(Query *parse);
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extern void pull_up_sublinks(PlannerInfo *root);
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extern void preprocess_function_rtes(PlannerInfo *root);
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extern void pull_up_subqueries(PlannerInfo *root);
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extern void flatten_simple_union_all(PlannerInfo *root);
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extern void reduce_outer_joins(PlannerInfo *root);
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extern void remove_useless_result_rtes(PlannerInfo *root);
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extern Relids get_relids_in_jointree(Node *jtnode, bool include_joins);
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extern Relids get_relids_for_join(Query *query, int joinrelid);
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/*
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* prototypes for preptlist.c
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*/
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extern void preprocess_targetlist(PlannerInfo *root);
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extern List *extract_update_targetlist_colnos(List *tlist);
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extern PlanRowMark *get_plan_rowmark(List *rowmarks, Index rtindex);
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/*
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* prototypes for prepagg.c
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*/
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extern void get_agg_clause_costs(PlannerInfo *root, AggSplit aggsplit,
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AggClauseCosts *agg_costs);
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extern void preprocess_aggrefs(PlannerInfo *root, Node *clause);
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/*
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* prototypes for prepunion.c
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*/
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extern RelOptInfo *plan_set_operations(PlannerInfo *root);
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#endif /* PREP_H */
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