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

Hi,

On Thu, Feb 9, 2023 at 6:55 PM Ajin Cherian <itsajin@gmail.com> wrote:
>
(v67)

I have some questions about adding the infrastructure for DDL deparsing.

Apart from the changes made by 0001 patch to add infrastructure for
DDL deparsing, 0002 patch seems to add some variables that are not
used in 0002 patch:

@@ -2055,6 +2055,7 @@ typedef struct AlterTableStmt
        List       *cmds;                       /* list of subcommands */
        ObjectType      objtype;                /* type of object */
        bool            missing_ok;             /* skip error if table
missing */
+       bool        table_like;         /* internally generated for
TableLikeClause */
 } AlterTableStmt;

@@ -39,6 +40,7 @@ typedef struct CollectedATSubcmd
 {
        ObjectAddress address;          /* affected column,
constraint, index, ... */
        Node       *parsetree;
+       char       *usingexpr;
 } CollectedATSubcmd;

 typedef struct CollectedCommand
@@ -62,6 +64,7 @@ typedef struct CollectedCommand
                {
                        Oid                     objectId;
                        Oid                     classId;
+                       bool            rewrite;
                        List       *subcmds;
                }                       alterTable;

These three variables are used in 0006 patch.

Looking at 0006 patch (Support DDL replication), it seems to me that
it includes not only DDL replication support but also changes for the
event trigger. For instance, the patch adds
EventTriggerAlterTypeStart() and EventTriggerAlterTypeEnd(). If these
changes are required for DDL deparse, should we include them in 0001
patch? Perhaps the same is true for
EventTriggerCollectCreatePublication() and friends. IIUC the DDL
deparse and DDL replication are independent features, so I think 0006
patch should not include any changes for DDL deparse infrastructure.

Also, 0003 and 0006 patches introduce SCT_Create/AlterPublication and
change DDL deparse so that it deparse CREATE/ALTER PUBLICATION in a
different way from other simple commands. Is there any reason for
that? I mean, since EventTriggerCollectCreatePublication() collects
the information from the parse tree, I wonder if we could use
SCT_Simple for them.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com