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RE: Column Filtering in Logical Replication

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

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From: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: vignesh C <vignesh21@gmail.com>, Rahila Syed <rahilasyed90@gmail.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2021-09-25T01:54:12Z
Lists: pgsql-hackers 
From Fri, Sep 24, 2021 9:25 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> On 2021-Sep-23, Amit Kapila wrote:
> 
> > Alvaro, do you have any thoughts on these proposed grammar changes?
> 
> Yeah, I think pubobj_name remains a problem in that you don't know its return
> type -- could be a String or a RangeVar, and the user of that production can't
> distinguish.  So you're still (unnecessarily, IMV) stashing an object of
> undetermined type into ->object.
> 
> I think you should get rid of both pubobj_name and pubobj_expr and do
> somethine like this:
> PublicationObjSpec:	TABLE ColId
> 					{
> 						$$ = makeNode(PublicationObjSpec);
> 						$$->pubobjtype = PUBLICATIONOBJ_TABLE;
> 						$$->rangevar = makeRangeVarFromQualifiedName($1, NULL, @1, yyscanner);
> 					}
> 			| TABLE ColId indirection
> 					{
> 						$$ = makeNode(PublicationObjSpec);
> 						$$->pubobjtype = PUBLICATIONOBJ_TABLE;
> 						$$->rangevar = makeRangeVarFromQualifiedName($1, $2, @1, yyscanner);
> 					}

Hi,

IIRC, the above grammar doesn't support extended relation expression (like:
"tablename * ", "ONLY tablename", "ONLY '( tablename )") which is part of rule
relation_expr. I think we should add these too. And if we move forward with the
design you proposed, we should do something like the following:

/* FOR TABLE and FOR ALL TABLES IN SCHEMA specifications */
PublicationObjSpec:
			TABLE relation_expr
							{
								$$ = makeNode(PublicationObjSpec);
								$$->pubobjtype = PUBLICATIONOBJ_TABLE;
								$$->rangevar = $2;
							}
			| ALL TABLES IN_P SCHEMA ColId
							{
								$$ = makeNode(PublicationObjSpec);
								$$->pubobjtype = PUBLICATIONOBJ_REL_IN_SCHEMA;
								$$->name = $5;
							}
			| ALL TABLES IN_P SCHEMA CURRENT_SCHEMA
							{
								$$ = makeNode(PublicationObjSpec);
								$$->pubobjtype = PUBLICATIONOBJ_CURRSCHEMA;
								$$->name = $5;
							}
			| extended_relation_expr	/* grammar like tablename * , ONLY tablename, ONLY ( tablename )*/
							{
								$$ = makeNode(PublicationObjSpec);
								$$->rangevar = makeRangeVarFromQualifiedName($1, $2, @1, yyscanner);
								$$->pubobjtype = PUBLICATIONOBJ_CONTINUATION;
							}
			| ColId
							{
								$$ = makeNode(PublicationObjSpec);
								$$->name = $1;
								$$->pubobjtype = PUBLICATIONOBJ_CONTINUATION;

							}
			| ColId indirection
							{
								$$ = makeNode(PublicationObjSpec);
								$$->rangevar = makeRangeVarFromQualifiedName($1, $2, @1, yyscanner);
								$$->pubobjtype = PUBLICATIONOBJ_CONTINUATION;

							}

Best regards,
Hou zj

Commits

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

  1. Doc: Explain about Column List feature.

  2. Doc: fix column list vs. replica identity rules.

  3. Prohibit combining publications with different column lists.

  4. Fix the check to limit sync workers.

  5. Wait for subscription to sync in t/031_column_list.sql

  6. Move prattrs to the pg_publication_rel section in docs

  7. Allow specifying column lists for logical replication

  8. Fix row filters with multiple publications

  9. Fix publish_as_relid with multiple publications

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

  11. Add index on pg_publication_rel.prpubid

  12. Avoid using DefElemAction in AlterPublicationStmt

  13. Small cleanups related to PUBLICATION framework code

  14. Add PublicationTable and PublicationRelInfo structs

  15. Fix various concurrency issues in logical replication worker launching