From 7103ebb7aae8ab8076b7e85f335ceb8fe799097c Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Mon, 28 Mar 2022 16:45:58 +0200 Subject: Add support for MERGE SQL command MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Author: Álvaro Herrera Author: Amit Langote Author: Simon Riggs Reviewed-by: Peter Eisentraut Reviewed-by: Andres Freund (earlier versions) Reviewed-by: Peter Geoghegan (earlier versions) Reviewed-by: Robert Haas (earlier versions) Reviewed-by: Japin Li Reviewed-by: Justin Pryzby Reviewed-by: Tomas Vondra Reviewed-by: Zhihong Yu 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 --- src/include/nodes/parsenodes.h | 61 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 57 insertions(+), 4 deletions(-) (limited to 'src/include/nodes/parsenodes.h') diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index 3b12a708ec0..6bf212b01a1 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -119,7 +119,7 @@ typedef struct Query { NodeTag type; - CmdType commandType; /* select|insert|update|delete|utility */ + CmdType commandType; /* select|insert|update|delete|merge|utility */ QuerySource querySource; /* where did I come from? */ @@ -130,7 +130,7 @@ typedef struct Query Node *utilityStmt; /* non-null if commandType == CMD_UTILITY */ int resultRelation; /* rtable index of target relation for - * INSERT/UPDATE/DELETE; 0 for SELECT */ + * INSERT/UPDATE/DELETE/MERGE; 0 for SELECT */ bool hasAggs; /* has aggregates in tlist or havingQual */ bool hasWindowFuncs; /* has window functions in tlist */ @@ -147,7 +147,11 @@ typedef struct Query List *cteList; /* WITH list (of CommonTableExpr's) */ List *rtable; /* list of range table entries */ - FromExpr *jointree; /* table join tree (FROM and WHERE clauses) */ + FromExpr *jointree; /* table join tree (FROM and WHERE clauses); + * also USING clause for MERGE */ + + List *mergeActionList; /* list of actions for MERGE (only) */ + bool mergeUseOuterJoin; /* whether to use outer join */ List *targetList; /* target list (of TargetEntry) */ @@ -1221,7 +1225,9 @@ typedef enum WCOKind WCO_VIEW_CHECK, /* WCO on an auto-updatable view */ WCO_RLS_INSERT_CHECK, /* RLS INSERT WITH CHECK policy */ WCO_RLS_UPDATE_CHECK, /* RLS UPDATE WITH CHECK policy */ - WCO_RLS_CONFLICT_CHECK /* RLS ON CONFLICT DO UPDATE USING policy */ + WCO_RLS_CONFLICT_CHECK, /* RLS ON CONFLICT DO UPDATE USING policy */ + WCO_RLS_MERGE_UPDATE_CHECK, /* RLS MERGE UPDATE USING policy */ + WCO_RLS_MERGE_DELETE_CHECK /* RLS MERGE DELETE USING policy */ } WCOKind; typedef struct WithCheckOption @@ -1537,6 +1543,39 @@ typedef struct CommonTableExpr ((Query *) (cte)->ctequery)->targetList : \ ((Query *) (cte)->ctequery)->returningList) +/* + * MergeWhenClause - + * raw parser representation of a WHEN clause in a MERGE statement + * + * This is transformed into MergeAction by parse analysis + */ +typedef struct MergeWhenClause +{ + NodeTag type; + bool matched; /* true=MATCHED, false=NOT MATCHED */ + CmdType commandType; /* INSERT/UPDATE/DELETE/DO NOTHING */ + OverridingKind override; /* OVERRIDING clause */ + Node *condition; /* WHEN conditions (raw parser) */ + List *targetList; /* INSERT/UPDATE targetlist */ + /* the following members are only used in INSERT actions */ + List *values; /* VALUES to INSERT, or NULL */ +} MergeWhenClause; + +/* + * MergeAction - + * Transformed representation of a WHEN clause in a MERGE statement + */ +typedef struct MergeAction +{ + NodeTag type; + bool matched; /* true=MATCHED, false=NOT MATCHED */ + CmdType commandType; /* INSERT/UPDATE/DELETE/DO NOTHING */ + OverridingKind override; /* OVERRIDING clause */ + Node *qual; /* transformed WHEN conditions */ + List *targetList; /* the target list (of TargetEntry) */ + List *updateColnos; /* target attribute numbers of an UPDATE */ +} MergeAction; + /* * TriggerTransition - * representation of transition row or table naming clause @@ -1737,6 +1776,20 @@ typedef struct UpdateStmt WithClause *withClause; /* WITH clause */ } UpdateStmt; +/* ---------------------- + * Merge Statement + * ---------------------- + */ +typedef struct MergeStmt +{ + NodeTag type; + RangeVar *relation; /* target relation to merge into */ + Node *sourceRelation; /* source relation */ + Node *joinCondition; /* join condition between source and target */ + List *mergeWhenClauses; /* list of MergeWhenClause(es) */ + WithClause *withClause; /* WITH clause */ +} MergeStmt; + /* ---------------------- * Select Statement * -- cgit v1.2.3