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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
37 lines
1.5 KiB
C
37 lines
1.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* paramassign.h
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* Functions for assigning PARAM_EXEC slots during planning.
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*
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* Portions Copyright (c) 1996-2024, 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/paramassign.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PARAMASSIGN_H
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#define PARAMASSIGN_H
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#include "nodes/pathnodes.h"
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extern Param *replace_outer_var(PlannerInfo *root, Var *var);
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extern Param *replace_outer_placeholdervar(PlannerInfo *root,
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PlaceHolderVar *phv);
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extern Param *replace_outer_agg(PlannerInfo *root, Aggref *agg);
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extern Param *replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp);
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extern Param *replace_outer_merge_support(PlannerInfo *root,
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MergeSupportFunc *msf);
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extern Param *replace_nestloop_param_var(PlannerInfo *root, Var *var);
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extern Param *replace_nestloop_param_placeholdervar(PlannerInfo *root,
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PlaceHolderVar *phv);
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extern void process_subquery_nestloop_params(PlannerInfo *root,
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List *subplan_params);
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extern List *identify_current_nestloop_params(PlannerInfo *root,
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Relids leftrelids);
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extern Param *generate_new_exec_param(PlannerInfo *root, Oid paramtype,
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int32 paramtypmod, Oid paramcollation);
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extern int assign_special_exec_param(PlannerInfo *root);
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#endif /* PARAMASSIGN_H */
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