Commits on Jul 30, 2025

1. Allow DELETE/UPDATE on partitioned tables with foreign partitions …

   Currently, DELETE or UPDATE on a partitioned table with foreign partitions
   fail with an error as below, if the FDW does not support the operation:
   
   	`ERROR: cannot delete from foreign table`
   
   This occurs because during executor initialization (ExecInitModifyTable),
   PostgreSQL scans all partitions of the target table and checks whether each one
   supports the requested operation. If any foreign partition's FDW lacks support
   for DELETE or UPDATE, the operation is rejected outright, even if that
   partition would not be affected by the query.
   
   As a result, DELETE/UPDATE operations are blocked even when they only target
   non-foreign partitions. This means the system errors out without considering
   whether foreign partitions are actually involved in the operation. Even if no
   matching rows exist in a foreign partition, the operation still fails.
   
   This commit defers the FDW check for foreign partitions from
   `ExecInitModifyTable` to `ExecDelete` and `ExecUpdate`. This change ensures
   that foreign partitions are checked only when they are actually targeted by the
   operation.
   
   However, if a DELETE or UPDATE is issued on the root partition and it includes
   foreign partitions that do not support the operation, it will still result in
   an error. This is intentional because the responsibility for managing data in
   foreign partitions lies with the user. Only after the user has removed relevant
   data from those foreign partitions will such operations on the root partition
   succeed.
   
   ** Mini repro: **
   ```
   CREATE EXTENSION file_fdw;
   CREATE SERVER file_server FOREIGN DATA WRAPPER file_fdw;
   CREATE TABLE pt (a int, b numeric) PARTITION BY RANGE(a);
   CREATE TABLE pt_part1 PARTITION OF pt FOR VALUES FROM (0) TO (10);
   INSERT INTO pt SELECT 5, 0.1;
   INSERT INTO pt SELECT 6, 0.2;
   
   CREATE FOREIGN TABLE ext (a int, b numeric) SERVER file_server OPTIONS (filename '/Users/sshirisha/workspace/postgres/src/test/regress/data/test_data_float.csv', format 'csv', delimiter ',');
   ALTER TABLE pt ATTACH PARTITION ext FOR VALUES FROM (10) TO (20);
   postgres=# SELECT * FROM pt;
    a  |  b
   ----+-----
     5 | 0.1
     6 | 0.2
    15 | 0.3
    21 | 0.4
   (4 rows)
   ```
   
   ** Before Fix: **
   ```
   postgres=# DELETE FROM pt WHERE b = 0.2;
   ERROR:  cannot delete from foreign table "ext"
   postgres=# DELETE FROM pt;
   ERROR:  cannot delete from foreign table "ext"
   
   postgres=# UPDATE pt set b = 0.5 WHERE b = 0.1;
   ERROR:  cannot update foreign table "ext"
   postgres=# UPDATE pt SET b = 0.5;
   ERROR:  cannot update foreign table "ext"
   ```
   
   ** After Fix: **
   ```
   postgres=# DELETE FROM pt WHERE b = 0.2;
   DELETE 1
   postgres=# DELETE FROM pt;
   ERROR:  cannot delete from foreign table "ext"
   
   postgres=# UPDATE pt SET b = 0.5 WHERE b = 0.1;
   UPDATE 1
   postgres=# UPDATE pt SET b = 0.5;
   ERROR:  cannot update foreign table "ext"
   ```
   
   Co-authored-by: Ashwin Agrawal <[email protected]>

   

   2 people authored and Commitfest Bot committed Jul 30, 2025
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2. [CF 5901] v1 - Proposal to allow DELETE/UPDATE on partitioned tables … …

   …with unsupported foreign partitions
   
   This branch was automatically generated by a robot using patches from an
   email thread registered at:
   
   https://commitfest.postgresql.org/patch/5901
   
   The branch will be overwritten each time a new patch version is posted to
   the thread, and also periodically to check for bitrot caused by changes
   on the master branch.
   
   Patch(es): https://www.postgresql.org/message-id/CAP3-t0-s-O8sV8bk85QYw-ancYOMrvf+3RieS5zd_qYxYJtTKg@mail.gmail.com
   Author(s): Shirisha V

   Commitfest Bot committed Jul 30, 2025
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