Re: Support logical replication of DDLs

Alvaro Herrera <alvherre@alvh.no-ip.org>

From: Alvaro Herrera <alvherre@alvh.no-ip.org>

To: vignesh C <vignesh21@gmail.com>

Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Japin Li <japinli@hotmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, rajesh singarapu <rajesh.rs0541@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Zheng Li <zhengli10@gmail.com>

Date: 2022-06-26T17:50:27Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Add a run_as_owner option to subscriptions.
- 482675987bcd 16.0 cited
Refactor pgoutput_change().
- da324d6cd45b 16.0 cited
Print the correct aliases for DML target tables in ruleutils.
- df931e9ab35b 11.20 landed
- c8a5f1685fb7 15.3 landed
- 4efb4f0d4878 13.11 landed
- 3dd287c14fac 12.15 landed
- 393430f57544 16.0 landed
- 14345f3c6a7b 14.8 landed
Fix object identity string for transforms
- 9a312562314a 16.0 landed
Add grantable MAINTAIN privilege and pg_maintain role.
- 60684dd834a2 16.0 cited
Get rid of recursion-marker values in enum AlterTableType
- 840ff5f451cd 16.0 cited
Release cache tuple when no longer needed
- ed0fbc8e5ac9 15.0 cited
Empty search_path in logical replication apply worker and walsender.
- 11da97024abb 14.0 cited
Refactor format_type APIs to be more modular
- a26116c6cbf4 11.0 cited
Use wrappers of PG_DETOAST_DATUM_PACKED() more.
- 3a0d473192b2 10.0 cited

On 2022-Jun-22, vignesh C wrote:

> 1) Creation of temporary table fails infinitely in the subscriber.
> CREATE TEMPORARY TABLE temp1 (a int primary key);
> 
> The above statement is converted to the below format:
> CREATE TEMPORARY TABLE  pg_temp.temp1 (a pg_catalog.int4   ,
> CONSTRAINT temp1_pkey PRIMARY KEY (a));
> While handling the creation of temporary table in the worker, the
> worker fails continuously with the following error:
> 2022-06-22 14:24:01.317 IST [240872] ERROR:  schema "pg_temp" does not exist

Perhaps one possible fix is to change the JSON format string used in
deparse_CreateStmt.  Currently, the following is used:

+       if (node->ofTypename)
+               fmtstr = "CREATE %{persistence}s TABLE %{if_not_exists}s %{identity}D "
+                       "OF %{of_type}T %{table_elements}s "
+                       "%{with_clause}s %{on_commit}s %{tablespace}s";
+       else
+               fmtstr = "CREATE %{persistence}s TABLE %{if_not_exists}s %{identity}D "
+                       "(%{table_elements:, }s) %{inherits}s "
+                       "%{with_clause}s %{on_commit}s %{tablespace}s";
+
+       createStmt =
+               new_objtree_VA(fmtstr, 1,
+                                          "persistence", ObjTypeString,
+                                          get_persistence_str(relation->rd_rel->relpersistence));

(Note that the word for the "persistence" element here comes straight
from relation->rd_rel->relpersistence.)  Maybe it would be more
appropriate to set the schema to empty when the table is temp, since the
temporary-ness is in the %{persistence} element, and thus there is no
need to schema-qualify the table name.

However, that would still replicate a command that involves a temporary
table, which perhaps should not be considered fit for replication.  So
another school of thought is that if the %{persistence} is set to
TEMPORARY, then it would be better to skip replicating the command
altogether.  I'm not sure how to plug that in the replication layer,
however.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"At least to kernel hackers, who really are human, despite occasional
rumors to the contrary" (LWN.net)