Re: row filtering for logical replication

On Mon, Jan 17, 2022 at 3:19 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> Some other comments:
> ==================
>

Few more comments:
==================
1.
+pgoutput_row_filter_init_expr(Node *rfnode)
+{
+ ExprState *exprstate;
+ Expr *expr;
+
+ /*
+ * This is the same code as ExecPrepareExpr() but that is not used because
+ * we have no EState to pass it.

Isn't it better to say "This is the same code as ExecPrepareExpr() but
that is not used because we want to cache the expression"? I feel if
we want we can allocate Estate as the patch is doing in
pgoutput_row_filter(), no?

2.
+ elog(DEBUG3, "row filter evaluates to %s (isnull: %s)",
+ DatumGetBool(ret) ? "true" : "false",
+ isnull ? "true" : "false");
+
+ if (isnull)
+ return false;

Won't the isnull condition's result in elog should be reversed?

3.
+ /*
+ * If the publication is FOR ALL TABLES IN SCHEMA and it overlaps
+ * with the current relation in the same schema then this is also
+ * treated same as if this table has no row filters (even if for
+ * other publications it does).
+ */
+ else if (list_member_oid(schemaPubids, pub->oid))
+ pub_no_filter = true;

The code will appear better if you can move the comments inside else
if. There are other places nearby this comment where we can follow the
same style.

4.
+ * Multiple ExprState entries might be used if there are multiple
+ * publications for a single table. Different publication actions don't
+ * allow multiple expressions to always be combined into one, so there is
+ * one ExprState per publication action. The exprstate array is indexed by
+ * ReorderBufferChangeType.
+ */
+ bool exprstate_valid;
+
+ /* ExprState array for row filter. One per publication action. */
+ ExprState *exprstate[NUM_ROWFILTER_PUBACTIONS];

It is not clear from comments here or at other places as to why we
need an array for row filter expressions? Can you please add comments
to explain the same? IIRC, it is primarily due to the reason that we
don't want to add the restriction that the publish operation 'insert'
should also honor RI columns restriction. If there are other reasons
then let's add those to comments as well.

--
With Regards,
Amit Kapila.