Thread: pgsql: Split ExecUpdate and ExecDelete into reusable pieces

pgsql: Split ExecUpdate and ExecDelete into reusable pieces

From
Alvaro Herrera
Date:
Split ExecUpdate and ExecDelete into reusable pieces

Create subroutines ExecUpdatePrologue / ExecUpdateAct /
ExecUpdateEpilogue, and similar for ExecDelete.

Introduce a new struct to be used internally in nodeModifyTable.c,
dubbed ModifyTableContext, which contains all context information needed
to perform these operations, as well as ExecInsert and others.

This allows using a different schedule and a different way of evaluating
the results of these operations, which can be exploited by a later
commit introducing support for MERGE.  It also makes ExecUpdate and
ExecDelete proper shorter and (hopefully) simpler.

Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Amit Langote <amitlangote09@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Reviewed-by: Zhihong Yu <zyu@yugabyte.com>
Discussion: https://postgr.es/m/202202271724.4z7xv3cf46kv@alvherre.pgsql

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/25e777cf8e547d7423d2e1e9da71f98b9414d59e

Modified Files
--------------
src/backend/executor/nodeModifyTable.c | 781 ++++++++++++++++++++-------------
src/tools/pgindent/typedefs.list       |   2 +
2 files changed, 484 insertions(+), 299 deletions(-)


Re: pgsql: Split ExecUpdate and ExecDelete into reusable pieces

From
Amit Langote
Date:
Hi Alvaro,

On Thu, Mar 17, 2022 at 7:47 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> Split ExecUpdate and ExecDelete into reusable pieces
>
> Create subroutines ExecUpdatePrologue / ExecUpdateAct /
> ExecUpdateEpilogue, and similar for ExecDelete.
>
> Introduce a new struct to be used internally in nodeModifyTable.c,
> dubbed ModifyTableContext, which contains all context information needed
> to perform these operations, as well as ExecInsert and others.
>
> This allows using a different schedule and a different way of evaluating
> the results of these operations, which can be exploited by a later
> commit introducing support for MERGE.  It also makes ExecUpdate and
> ExecDelete proper shorter and (hopefully) simpler.

I noticed that we failed to update a comment mentioning a now obsolete
parameter of ExecCrossPartitionUpdate().  Attached a patch to fix that
and an old typo in the same sentence.

-- 
Amit Langote
EDB: http://www.enterprisedb.com

Attachment

Re: pgsql: Split ExecUpdate and ExecDelete into reusable pieces

From
Amit Langote
Date:
On Sat, Mar 19, 2022 at 12:59 PM Amit Langote <amitlangote09@gmail.com> wrote:
> On Thu, Mar 17, 2022 at 7:47 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> >
> > Split ExecUpdate and ExecDelete into reusable pieces
> >
> > Create subroutines ExecUpdatePrologue / ExecUpdateAct /
> > ExecUpdateEpilogue, and similar for ExecDelete.
> >
> > Introduce a new struct to be used internally in nodeModifyTable.c,
> > dubbed ModifyTableContext, which contains all context information needed
> > to perform these operations, as well as ExecInsert and others.
> >
> > This allows using a different schedule and a different way of evaluating
> > the results of these operations, which can be exploited by a later
> > commit introducing support for MERGE.  It also makes ExecUpdate and
> > ExecDelete proper shorter and (hopefully) simpler.
>
> I noticed that we failed to update a comment mentioning a now obsolete
> parameter of ExecCrossPartitionUpdate().  Attached a patch to fix that
> and an old typo in the same sentence.

Actually, I also noticed that the v16 patch you posted in the "Re: a
misbehavior of partition row movement (?)" thread contained this same
fix.  I like the wording in that patch, though I guess it's better to
commit the fix separately from the big patch there, which I guess may
have been your intention anyway.  So, here's a v2.

-- 
Amit Langote
EDB: http://www.enterprisedb.com

Attachment

Re: pgsql: Split ExecUpdate and ExecDelete into reusable pieces

From
Alvaro Herrera
Date:
On 2022-Mar-19, Amit Langote wrote:

> Actually, I also noticed that the v16 patch you posted in the "Re: a
> misbehavior of partition row movement (?)" thread contained this same
> fix.  I like the wording in that patch, though I guess it's better to
> commit the fix separately from the big patch there, which I guess may
> have been your intention anyway.  So, here's a v2.

Yeah, I was of two minds about pushing it separately -- and you
mentioning it now pushed me to do that.  So, it's done now.

-- 
Álvaro Herrera              Valdivia, Chile  —  https://www.EnterpriseDB.com/
"Hay que recordar que la existencia en el cosmos, y particularmente la
elaboración de civilizaciones dentro de él no son, por desgracia,
nada idílicas" (Ijon Tichy)