digoal
2024-03-18
PostgreSQL , PolarDB , DuckDB , merge , returning
Add RETURNING support to MERGE.
author Dean Rasheed <dean.a.rasheed@gmail.com>
Sun, 17 Mar 2024 13:58:59 +0000 (13:58 +0000)
committer Dean Rasheed <dean.a.rasheed@gmail.com>
Sun, 17 Mar 2024 13:58:59 +0000 (13:58 +0000)
commit c649fa24a42ba89bf5460c7110e4fc8eeca65959
tree de7d51489c6c6fff56fddad66c0ced2aa427d6a5 tree
parent 6a004f1be87d34cfe51acf2fe2552d2b08a79273 commit | diff
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
