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Date: Sun, 05 Oct 2025 11:47:59 -0300
From: "Euler Taveira" <euler@eulerto.com>
To: webbohan@qq.com, pgsql-bugs@lists.postgresql.org
Message-Id: <5b04da16-c2de-464b-8677-9e4991b28e55@app.fastmail.com>
In-Reply-To: <19073-93772b97a2f1ecf3@postgresql.org>
References: <19073-93772b97a2f1ecf3@postgresql.org>
Subject: Re: BUG #19073: there are meaningless code in _SPI_execute_plan()
 when
 canSetTag is true
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On Sat, Oct 4, 2025, at 11:29 PM, PG Bug reporting form wrote:
> In function _SPI_execute_plan(), `my_tuptable` is local variable and
> initialized as NULL.
> If plan is canSetTag subqueries, `SPI_freetuptable(my_tuptable)` is
> meaningless, because `my_tuptable` is NULL.
> We'd better remove this code.
>

There could be multiple statements. The first case will call SPI_freetuptable()
and it is a noop. The code path you are referring to is inside a foreach loop
and a previous statement might set my_tuptable and needs to be freed before
reusing it. That's exactly what the comment says.

            /*
             * The last canSetTag query sets the status values returned to the
             * caller.  Be careful to free any tuptables not returned, to
             * avoid intra-transaction memory leak.
             */
            if (canSetTag)
            {
                my_processed = _SPI_current->processed;
                SPI_freetuptable(my_tuptable);
                my_tuptable = _SPI_current->tuptable;
                my_res = res; 
            }


-- 
Euler Taveira
EDB   https://www.enterprisedb.com/