Horton

Re: row filtering for logical replication

Peter Smith <smithpb2250@gmail.com>

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From: Peter Smith <smithpb2250@gmail.com>
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, vignesh C <vignesh21@gmail.com>, Greg Nancarrow <gregn4422@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Ajin Cherian <itsajin@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 Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-12-08T06:03:37Z
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 Thu, Dec 2, 2021 at 2:59 PM houzj.fnst@fujitsu.com
<houzj.fnst@fujitsu.com> wrote:
>
...
> Attach the v44-0005 top-up patch.
> This version addressed all the comments received so far,
> mainly including the following changes:
> 1) rename rfcol_valid_for_replica to rfcol_valid
> 2) Remove the struct PublicationInfo and add the rfcol_valid flag directly in relation
> 3) report the invalid column number in the error message.
> 4) Rename some function to match the usage.
> 5) Fix some typos and add some code comments.
> 6) Fix a miss in testcase.

Below are my review comments for the most recent v44-0005 (top-up) patch:

======

1. src/backend/executor/execReplication.c
+ invalid_rfcol = RelationGetInvalRowFilterCol(rel);
+
+ /*
+ * It is only safe to execute UPDATE/DELETE when all columns of the row
+ * filters from publications which the relation is in are part of the
+ * REPLICA IDENTITY.
+ */
+ if (invalid_rfcol != InvalidAttrNumber)
+ {

It seemed confusing that when the invalid_rfcol is NOT invalid at all
then it is InvalidAttrNumber, so perhaps this code would be easier to
read if instead the condition was written just as:
---
if (invalid_rfcol)
{
...
}
---

====

2. invalid_rfcol var name
This variable name is used in a few places but I thought it was too
closely named with the "rfcol_valid" variable even though it has a
completely different meaning. IMO "invalid_rfcol" might be better
named "invalid_rfcolnum" or something like that to reinforce that it
is an AttributeNumber.

====

3. src/backend/utils/cache/relcache.c - function comment
+ * If not all the row filter columns are part of REPLICA IDENTITY, return the
+ * invalid column number, InvalidAttrNumber otherwise.
+ */

Minor rewording:
"InvalidAttrNumber otherwise." --> "otherwise InvalidAttrNumber."

====

4. src/backend/utils/cache/relcache.c - function name
+AttrNumber
+RelationGetInvalRowFilterCol(Relation relation)

IMO nothing was gained by saving 2 chars of the name.
"RelationGetInvalRowFilterCol" --> "RelationGetInvalidRowFilterCol"

====

5. src/backend/utils/cache/relcache.c
+/* For invalid_rowfilter_column_walker. */
+typedef struct {
+ AttrNumber invalid_rfcol;
+ Bitmapset  *bms_replident;
+} rf_context;
+

The members should be commented.

====

6. src/include/utils/rel.h
  /*
+ * true if the columns of row filters from all the publications the
+ * relation is in are part of replica identity.
+ */
+ bool rd_rfcol_valid;

I felt the member comment is not quite telling the full story. e.g.
IIUC this member is also true when pubaction is something other than
update/delete - but that case doesn't even do replica identity
checking at all. There might not even be any replica identity.

====

6. src/test/regress/sql/publication.sql
 CREATE PUBLICATION testpub6 FOR TABLE rf_tbl_abcd_pk WHERE (a > 99);
+-- fail - "a" is in PK but it is not part of REPLICA IDENTITY INDEX
+update rf_tbl_abcd_pk set a = 1;
+DROP PUBLICATION testpub6;
 -- ok - "c" is not in PK but it is part of REPLICA IDENTITY INDEX
-SET client_min_messages = 'ERROR';
 CREATE PUBLICATION testpub6 FOR TABLE rf_tbl_abcd_pk WHERE (c > 99);
 DROP PUBLICATION testpub6;
-RESET client_min_messages;
--- fail - "a" is not in REPLICA IDENTITY INDEX
 CREATE PUBLICATION testpub6 FOR TABLE rf_tbl_abcd_nopk WHERE (a > 99);
+-- fail - "a" is not in REPLICA IDENTITY INDEX
+update rf_tbl_abcd_nopk set a = 1;

The "update" DML should be uppercase "UPDATE" for consistency with the
surrounding tests.

------
Kind Regards,
Peter Smith.
Fujitsu Australia