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Add RETURNING support to MERGE.

This allows a RETURNING clause to be appended to a MERGE query, to
return values based on each row inserted, updated, or deleted. As with
plain INSERT, UPDATE, and DELETE commands, the returned values are
based on the new contents of the target table for INSERT and UPDATE
actions, and on its old contents for DELETE actions. Values from the
source relation may also be returned.

As with INSERT/UPDATE/DELETE, the output of MERGE ... RETURNING may be
used as the source relation for other operations such as WITH queries
and COPY commands.

Additionally, a special function merge_action() is provided, which
returns 'INSERT', 'UPDATE', or 'DELETE', depending on the action
executed for each row. The merge_action() function can be used
anywhere in the RETURNING list, including in arbitrary expressions and
subqueries, but it is an error to use it anywhere outside of a MERGE
query's RETURNING list.

Dean Rasheed, reviewed by Isaac Morland, Vik Fearing, Alvaro Herrera,
Gurjeet Singh, Jian He, Jeff Davis, Merlin Moncure, Peter Eisentraut,
and Wolfgang Walther.

Discussion: http://postgr.es/m/CAEZATCWePEGQR5LBn-vD6SfeLZafzEm2Qy_L_Oky2=qw2w3Pzg@mail.gmail.com
This commit is contained in:
Dean Rasheed
2024-03-17 13:58:59 +00:00
parent 6a004f1be8
commit c649fa24a4
61 changed files with 1198 additions and 216 deletions

View File

@@ -243,6 +243,7 @@ typedef enum ExprEvalOp
EEOP_AGGREF,
EEOP_GROUPING_FUNC,
EEOP_WINDOW_FUNC,
EEOP_MERGE_SUPPORT_FUNC,
EEOP_SUBPLAN,
/* aggregation related nodes */
@@ -810,6 +811,8 @@ extern void ExecEvalJsonConstructor(ExprState *state, ExprEvalStep *op,
ExprContext *econtext);
extern void ExecEvalJsonIsPredicate(ExprState *state, ExprEvalStep *op);
extern void ExecEvalGroupingFunc(ExprState *state, ExprEvalStep *op);
extern void ExecEvalMergeSupportFunc(ExprState *state, ExprEvalStep *op,
ExprContext *econtext);
extern void ExecEvalSubPlan(ExprState *state, ExprEvalStep *op,
ExprContext *econtext);
extern void ExecEvalWholeRowVar(ExprState *state, ExprEvalStep *op,

View File

@@ -97,6 +97,7 @@ typedef struct _SPI_plan *SPIPlanPtr;
#define SPI_OK_REL_UNREGISTER 16
#define SPI_OK_TD_REGISTER 17
#define SPI_OK_MERGE 18
#define SPI_OK_MERGE_RETURNING 19
#define SPI_OPT_NONATOMIC (1 << 0)