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Re: row filtering for logical replication

Greg Nancarrow <gregn4422@gmail.com>

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From: Greg Nancarrow <gregn4422@gmail.com>
To: Euler Taveira <euler@eulerto.com>
Cc: Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.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: 2021-07-14T11:21:36Z
Lists: pgsql-hackers

Commits

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  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 Wed, Jul 14, 2021 at 6:38 AM Euler Taveira <euler@eulerto.com> wrote:
>
> Peter, thanks for quickly check the new patch. I'm attaching a new patch (v19)
> that addresses (a) this new review, (b) Tomas' review and (c) Greg's review. I
> also included the copy/equal node support for the new node (PublicationTable)
> mentioned by Tomas in another email.
>

Some minor v19 patch review points you might consider for your next
patch version:
(I'm still considering the other issues raised about WHERE clauses and
filtering)


(1) src/backend/commands/publicationcmds.c
OpenTableList

Some suggested abbreviations:

BEFORE:
if (IsA(lfirst(lc), PublicationTable))
   whereclause = true;
else
   whereclause = false;

AFTER:
whereclause = IsA(lfirst(lc), PublicationTable);


BEFORE:
if (whereclause)
   pri->whereClause = t->whereClause;
else
   pri->whereClause = NULL;

AFTER:
pri->whereClause = whereclause? t->whereClause : NULL;


(2) src/backend/parser/parse_expr.c

I think that the check below:

/* Functions are not allowed in publication WHERE clauses */
if (pstate->p_expr_kind == EXPR_KIND_PUBLICATION_WHERE &&
nodeTag(expr) == T_FuncCall)
    ereport(ERROR,
        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
        errmsg("functions are not allowed in publication WHERE expressions"),
        parser_errposition(pstate, exprLocation(expr))));

should be moved down into the "T_FuncCall" case of the switch
statement below it, so that "if (pstate->p_expr_kind ==
EXPR_KIND_PUBLICATION_WHERE" doesn't get checked every call to
transformExprRecurse() regardless of the expression Node type.


(3) Save a nanosecond when entry->exprstate is already NIL:

BEFORE:
if (entry->exprstate != NIL)
   list_free_deep(entry->exprstate);
entry->exprstate = NIL;

AFTER:
if (entry->exprstate != NIL)
{
   list_free_deep(entry->exprstate);
   entry->exprstate = NIL;
}


Regards,
Greg Nancarrow
Fujitsu Australia