RE: Support logical replication of DDLs - Mailing list pgsql-hackers

On Mon, Mar 6, 2023 14:34 AM Ajin Cherian <itsajin@gmail.com> wrote:
> Changes are in patch 1 and patch 2

Thanks for updating the patch set.

Here are some comments:

For v-75-0002* patch.
1. In the function deparse_AlterRelation.
+        if ((sub->address.objectId != relId &&
+             sub->address.objectId != InvalidOid) &&
+            !(subcmd->subtype == AT_AddConstraint &&
+              subcmd->recurse) &&
+            istable)
+            continue;

I think when we execute the command "ALTER TABLE ... ADD (index)" (subtype is
AT_AddIndexConstraint or AT_AddIndex), this command will be skipped for parsing.
I think we need to parse both types of commands here.

===
For v-75-0003* patch.
2. In the function deparse_CreateSeqStmt.
It seems that we are not deparsing the "AS data_type" clause (CREATE SEQUENCE
... AS data_type). I think this causes all data_type to be default (bigint)
after executing the parsed CreateSeq command.

~~~

3. In the function deparse_CreateTrigStmt
+        tgargs = DatumGetByteaP(fastgetattr(trigTup,
+                                            Anum_pg_trigger_tgargs,
+                                            RelationGetDescr(pg_trigger),
+                                            &isnull));
+        if (isnull)
+            elog(ERROR, "null tgargs for trigger \"%s\"",
+                 NameStr(trigForm->tgname));
+        argstr = (char *) VARDATA(tgargs);
+        lentgargs = VARSIZE_ANY_EXHDR(tgargs);
a.
I think it might be better to invoke the function DatumGetByteaP after checking
the flag "isnull". Because if "isnull" is true, I think an unexpected pointer
((NULL)->va_header) will be used when invoking macro VARATT_IS_4B_U.

b.
Since commit 3a0d473 recommends using macro DatumGetByteaPP instead of
DatumGetByteaP, and the function pg_get_triggerdef_worker also uses macro
DatumGetByteaPP, I think it might be better to use DatumGetByteaPP here.

~~~

4. In the function deparse_CreateTrigStmt
+    append_object_object(ret, "EXECUTE PROCEDURE %{function}s", tmp_obj);

Since the use of the keyword "PROCEDURE" is historical, I think it might be
better to use "FUNCTION".

===
For v-75-0004* patch.
5. File src/test/modules/test_ddl_deparse_regress/README.md
+1. Test that the generated JSON blob is expected using SQL tests.
+2. Test that the re-formed DDL command is expected using SQL tests.
+3. Test    that the re-formed DDL command has the same effect as the original command
+   by comparing    the results of pg_dump,    using the SQL tests in 1 and 2.
+4. Test    that new DDL syntax is handled by the DDL deparser by capturing and deparing
+   DDL commands    ran by pg_regress.

Inconsistent spacing:
\t -> blank space

Regards,
Wang wei