Horton

Re: TRUNCATE on foreign table

Kazutaka Onishi <onishi@heterodb.com>

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From: Kazutaka Onishi <onishi@heterodb.com>
To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Cc: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Zhihong Yu <zyu@yugabyte.com>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>, Kohei KaiGai <kaigai@heterodb.com>
Date: 2021-02-09T14:15:03Z
Lists: pgsql-hackers 
> IIUC, "truncatable" would be set to "false" for relations which do not
> have physical storage e.g. views but will be true for regular tables.

"truncatable" option is just for the foreign table and it's not related
with whether it's on a physical storage or not.
"postgres_fdw" already has "updatable" option to make the table read-only.
However, "updatable" is for DML, and it's not suitable for TRUNCATE.
Therefore new options "truncatable" was added.

Please refer to this message for details.
https://www.postgresql.org/message-id/20200128040346.GC1552%40paquier.xyz

> DELETE is very different from TRUNCATE. Application may want to DELETE
> based on a join with a local table and hence it can not be executed on
> a foreign server. That's not true with TRUNCATE.

Yeah, As you say, Applications doesn't need  TRUNCATE.
We're focusing for analytical use, namely operating huge data.
TRUNCATE can erase rows faster than DELETE.

Commits

  1. doc: Review for "Allow TRUNCATE command to truncate foreign tables".

  2. Don't pass "ONLY" options specified in TRUNCATE to foreign data wrapper.

  3. Support tab-complete for TRUNCATE on foreign tables.

  4. Allow TRUNCATE command to truncate foreign tables.

  5. Add support for asynchronous execution.