RE: row filtering for logical replication

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

From: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: Ajin Cherian <itsajin@gmail.com>, Greg Nancarrow <gregn4422@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Euler Taveira <euler@eulerto.com>, Rahila Syed <rahilasyed90@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Önder Kalacı <onderkalaci@gmail.com>, japin <japinli@hotmail.com>, Michael Paquier <michael@paquier.xyz>, David Steele <david@pgmasters.net>, Craig Ringer <craig@2ndquadrant.com>, Amit Kapila <amit.kapila16@gmail.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2021-11-08T06:53:45Z
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 →
  1. Release cache tuple when no longer needed

  2. Add some additional tests for row filters in logical replication.

  3. Fix one of the tests introduced in commit 52e4f0cd47.

  4. Allow specifying row filters for logical replication of tables.

  5. Move scanint8() to numutils.c

  6. Replace Test::More plans with done_testing

  7. Reduce relcache access in WAL sender streaming logical changes

  8. Small cleanups related to PUBLICATION framework code

  9. Add a view to show the stats of subscription workers.

  10. Allow publishing the tables of schema.

  11. Doc: improve documentation of CREATE/ALTER SUBSCRIPTION.

  12. Add PublicationTable and PublicationRelInfo structs

  13. Remove unused argument "txn" in maybe_send_schema().

  14. Add prepare API support for streaming transactions in logical replication.

  15. Unify PostgresNode's new() and get_new_node() methods

  16. Use l*_node() family of functions where appropriate

  17. Add support for prepared transactions to built-in logical replication.

  18. Restore the portal-level snapshot after procedure COMMIT/ROLLBACK.

  19. Rename a parse node to be more general

  20. Remove unused column atttypmod from initial tablesync query

  21. SEARCH and CYCLE clauses

On Fri, Nov 5, 2021 1:14 PM Peter Smith <smithpb2250@gmail.com> wrote:
> PSA new set of v37* patches.

Thanks for updating the patches.
Few comments:

1) v37-0001

I think it might be better to also show the filter expression in '\d+
tablename' command after publication description.

2) v37-0004

+	/* Scan the expression tree for referenceable objects */
+	find_expr_references_walker(expr, &context);
+
+	/* Remove any duplicates */
+	eliminate_duplicate_dependencies(context.addrs);
+

The 0004 patch currently use find_expr_references_walker to get all the
reference objects. I am thinking do we only need get the columns in the
expression ? I think maybe we can check the replica indentity like[1].

3) v37-0005

- no parse nodes of any kind other than Var, OpExpr, Const, BoolExpr, FuncExpr

I think there could be other node type which can also be considered as simple
expression, for exmaple T_NullIfExpr.

Personally, I think it's natural to only check the IMMUTABLE and
whether-user-defined in the new function rowfilter_walker. We can keep the
other row-filter errors which were thrown for EXPR_KIND_PUBLICATION_WHERE in
the 0001 patch.

[1]
rowfilter_expr_checker
...
			if (replica_identity == REPLICA_IDENTITY_DEFAULT)
				context.bms_replident = RelationGetIndexAttrBitmap(rel, INDEX_ATTR_BITMAP_PRIMARY_KEY);
			else
				context.bms_replident = RelationGetIndexAttrBitmap(rel, INDEX_ATTR_BITMAP_IDENTITY_KEY);

			(void) rowfilter_expr_replident_walker(rfnode, &context);

...
static bool
rowfilter_expr_replident_walker(Node *node, rf_context *context)
{
	if (node == NULL)
		return false;

	if (IsA(node, Var))
	{
		Oid			relid = RelationGetRelid(context->rel);
		Var		   *var = (Var *) node;
		AttrNumber 	attnum = var->varattno - FirstLowInvalidHeapAttributeNumber;

		if (!bms_is_member(attnum, context->bms_replident))
		{
			const char *colname = get_attname(relid, attnum, false);
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
					errmsg("cannot add relation \"%s\" to publication",
							RelationGetRelationName(context->rel)),
					errdetail("Row filter column \"%s\" is not part of the REPLICA IDENTITY",
								colname)));

			return false;
		}

		return true;
	}

	return expression_tree_walker(node, rowfilter_expr_replident_walker,
								  (void *) context);
}

Best regards,
Hou zj