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Disallow COPY FREEZE on foreign tables.

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This didn't actually work: the COPY succeeds, but the FREEZE
optimization isn't applied.  There doesn't seem to be an easy way
to support FREEZE on foreign tables, so let's follow the precedent
established by commit 5c9a5513a3 by raising an error early.  This
is arguably a bug fix, but due to the lack of reports, the minimal
discussion on the mailing list, and the potential to break existing
scripts, I am not back-patching it for now.

Author: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Zhang Mingli <zmlpostgres@gmail.com>
Discussion: https://postgr.es/m/CAA5RZ0ujeNgKpE3OrLtR%3DeJGa5LkGMekFzQTwjgw%3DrzaLufQLQ%40mail.gmail.com
This commit is contained in:
Nathan Bossart 2025-02-06 15:23:40 -06:00
parent a99a32e43e
commit 401a6956fa
4 changed files with 25 additions and 1 deletions
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2
doc/src/sgml/ref/copy.sgml
View File

@ -237,7 +237,7 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
or truncated in the current subtransaction, there are no cursors
open and there are no older snapshots held by this transaction. It is
currently not possible to perform a <command>COPY FREEZE</command> on
a partitioned table.
a partitioned table or foreign table.
This option is only allowed in <command>COPY FROM</command>.
</para>
<para>

6
src/backend/commands/copyfrom.c
View File

@ -740,6 +740,12 @@ CopyFrom(CopyFromState cstate)
errmsg("cannot perform COPY FREEZE on a partitioned table")));
}
/* There's currently no support for COPY FREEZE on foreign tables. */
if (cstate->rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot perform COPY FREEZE on a foreign table")));
/*
* Tolerate one registration for the benefit of FirstXactSnapshot.
* Scan-bearing queries generally create at least two registrations,

8
src/test/regress/expected/copy.out
View File

@ -325,3 +325,11 @@ SELECT tableoid::regclass, id % 2 = 0 is_even, count(*) from parted_si GROUP BY
(2 rows)
DROP TABLE parted_si;
-- ensure COPY FREEZE errors for foreign tables
begin;
create foreign data wrapper copytest_wrapper;
create server copytest_server foreign data wrapper copytest_wrapper;
create foreign table copytest_foreign_table (a int) server copytest_server;
copy copytest_foreign_table from stdin (freeze);
ERROR: cannot perform COPY FREEZE on a foreign table
rollback;

10
src/test/regress/sql/copy.sql
View File

@ -348,3 +348,13 @@ COPY parted_si(id, data) FROM :'filename';
SELECT tableoid::regclass, id % 2 = 0 is_even, count(*) from parted_si GROUP BY 1, 2 ORDER BY 1;
DROP TABLE parted_si;
-- ensure COPY FREEZE errors for foreign tables
begin;
create foreign data wrapper copytest_wrapper;
create server copytest_server foreign data wrapper copytest_wrapper;
create foreign table copytest_foreign_table (a int) server copytest_server;
copy copytest_foreign_table from stdin (freeze);
1
\.
rollback;