From: Tom Lane <tgl@sss.pgh.pa.us>
To: Zhihong Yu <zyu@yugabyte.com>
cc: PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>,
        Richard Guo <guofenglinux@gmail.com>,
        "Finnerty,
    Jim" <jfinnert@amazon.com>
Subject: Re: Making Vars outer-join aware
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Comments: In-reply-to Zhihong Yu <zyu@yugabyte.com>
	message dated "Mon, 01 Aug 2022 13:28:37 -0700"
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Date: Mon, 01 Aug 2022 16:26:30 -0400
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Zhihong Yu <zyu@yugabyte.com> writes:
> For v3-0003-label-Var-nullability-in-parser.patch :

> +   if (rtindex > 0 && rtindex <= list_length(pstate->p_nullingrels))
> +       relids = (Bitmapset *) list_nth(pstate->p_nullingrels, rtindex - 1);
> +   else
> +       relids = NULL;
> +
> +   /*
> +    * Merge with any already-declared nulling rels.  (Typically there won't
> +    * be any, but let's get it right if there are.)
> +    */
> +   if (relids != NULL)

> It seems the last if block can be merged into the previous if block. That
> way `relids = NULL` can be omitted.

No, because the list entry we fetch could be NULL.

			regards, tom lane