Horton

Re: row filtering for logical replication

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.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>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-11-05T08:49:01Z
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 at 10:44 AM Peter Smith <smithpb2250@gmail.com> wrote:
>
> PSA new set of v37* patches.
>

Few comments about changes made to the patch to rebase it:
1.
+#if 1
+ // FIXME - can we do a better job if integrating this with the schema changes
+ /*
+ * Remove all publication-table mappings.  We could possibly remove (i)
+ * tables that are not found in the new table list and (ii) tables that
+ * are being re-added with a different qual expression. For (ii),
+ * simply updating the existing tuple is not enough, because of qual
+ * expression dependencies.
+ */
+ foreach(oldlc, oldrelids)
+ {
+ Oid oldrelid = lfirst_oid(oldlc);
+ PublicationRelInfo *oldrel;
+
+ oldrel = palloc(sizeof(PublicationRelInfo));
+ oldrel->relid = oldrelid;
+ oldrel->whereClause = NULL;
+ oldrel->relation = table_open(oldrel->relid,
+   ShareUpdateExclusiveLock);
+ delrels = lappend(delrels, oldrel);
+ }
+#else
  CheckObjSchemaNotAlreadyInPublication(rels, schemaidlist,
    PUBLICATIONOBJ_TABLE);

I think for the correct merge you need to just call
CheckObjSchemaNotAlreadyInPublication() before this for loop. BTW, I
have a question regarding this implementation. Here, it has been
assumed that the new rel will always be specified with a different
qual, what if there is no qual or if the qual is the same?

2.
+preprocess_pubobj_list(List *pubobjspec_list, core_yyscan_t
yyscanner, bool alter_drop)
 {
  ListCell   *cell;
  PublicationObjSpec *pubobj;
@@ -17341,7 +17359,15 @@ preprocess_pubobj_list(List *pubobjspec_list,
core_yyscan_t yyscanner)
  errcode(ERRCODE_SYNTAX_ERROR),
  errmsg("invalid table name at or near"),
  parser_errposition(pubobj->location));
- else if (pubobj->name)
+
+ /* cannot use WHERE w-filter for DROP TABLE from publications */
+ if (pubobj->pubtable && pubobj->pubtable->whereClause && alter_drop)
+ ereport(ERROR,
+ errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("invalid use of WHERE row-filter in ALTER PUBLICATION ... DROP TABLE"),
+ parser_errposition(pubobj->location));
+

This change looks a bit ad-hoc to me. Can we handle this at a later
point of time in publicationcmds.c?

3.
- | ColId
+ | ColId OptWhereClause
  {
  $$ = makeNode(PublicationObjSpec);
  $$->pubobjtype = PUBLICATIONOBJ_CONTINUATION;
- $$->name = $1;
+ if ($2)
+ {
+ $$->pubtable = makeNode(PublicationTable);
+ $$->pubtable->relation = makeRangeVar(NULL, $1, @1);
+ $$->pubtable->whereClause = $2;
+ }
+ else
+ {
+ $$->name = $1;
+ }

Again this doesn't appear to be the right way. I think this should be
handled at a later point.

-- 
With Regards,
Amit Kapila.