Re: BUG #19382: Server crash at __nss_database_lookup

Hi Surya Poondla:

After applying the patch on the master branch, I debugged it and the type mismatch issue is indeed not as bad as before. I haven't looked at this patch much, but I'm a little worried about performance issues here.

I have one more question: Can we iterate through the code first to get the value of `need_conversion`, and then allocate memory and perform subsequent operations only if necessary? Of course, this is just my opinion. Thank you.

Regards,
songjinzhou

songjinzhou
tsinghualucky912(at)foxmail(dot)com

原始邮件


发件人：surya poondla <suryapoondla4(at)gmail(dot)com&gt;
发件时间：2026年3月19日 13:00
收件人：dllggyx <dllggyx(at)outlook(dot)com&gt;, pgsql-bugs <pgsql-bugs(at)lists(dot)postgresql(dot)org&gt;
主题：Re: BUG #19382: Server crash at __nss_database_lookup

Hi All,

I was able to reproduce the crash on laster master (19), the above patch applies cleanly on postgres 19 and doesn't crash the server.

psql (19devel)
Type "help" for help.

postgres=# DROP FUNCTION IF EXISTS bar();
NOTICE: &nbsp;function bar() does not exist, skipping
DROP FUNCTION
postgres=# &nbsp; DROP TYPE IF EXISTS foo CASCADE;
NOTICE: &nbsp;type "foo" does not exist, skipping
DROP TYPE
postgres=# &nbsp; CREATE TYPE foo AS (a INT, b INT);
CREATE TYPE
postgres=# &nbsp; CREATE FUNCTION bar() RETURNS RECORD AS $$
postgres$# &nbsp; DECLARE
postgres$# &nbsp; &nbsp; &nbsp; r foo := ROW(123, power(2, 30));
postgres$# &nbsp; BEGIN
postgres$# &nbsp; &nbsp; &nbsp; ALTER TYPE foo ALTER ATTRIBUTE b TYPE TEXT;
postgres$# &nbsp; &nbsp; &nbsp; RETURN r;
postgres$# &nbsp; END;
postgres$# &nbsp; $$ LANGUAGE plpgsql;
CREATE FUNCTION
postgres=# SELECT bar();
&nbsp; &nbsp; &nbsp; &nbsp;bar
------------------
&nbsp;(123,1073741824)
(1 row)

postgres=# DROP FUNCTION IF EXISTS bar1();
NOTICE: &nbsp;function bar1() does not exist, skipping
DROP FUNCTION
postgres=# &nbsp; DROP TYPE IF EXISTS foo1 CASCADE;
NOTICE: &nbsp;type "foo1" does not exist, skipping
DROP TYPE
postgres=# &nbsp; CREATE TYPE foo1 AS (a INT, b INT);
CREATE TYPE
postgres=# &nbsp; CREATE FUNCTION bar1(OUT r1 foo1) AS $$
postgres$# &nbsp; BEGIN
postgres$# &nbsp; &nbsp; &nbsp; r1 := ROW(1, 2);
postgres$# &nbsp; &nbsp; &nbsp; ALTER TYPE foo1 ALTER ATTRIBUTE b TYPE TEXT;
postgres$# &nbsp; &nbsp; &nbsp; RETURN;
postgres$# &nbsp; END;
postgres$# &nbsp; $$ LANGUAGE plpgsql;
CREATE FUNCTION
postgres=# SELECT bar1();
&nbsp;bar1
-------
&nbsp;(1,2)
(1 row)

postgres=# DROP FUNCTION IF EXISTS bar2();
NOTICE: &nbsp;function bar2() does not exist, skipping
DROP FUNCTION
postgres=# &nbsp; DROP TYPE IF EXISTS foo2 CASCADE;
NOTICE: &nbsp;type "foo2" does not exist, skipping
DROP TYPE
postgres=# &nbsp; CREATE TYPE foo2 AS (a INT, b TEXT);
CREATE TYPE
postgres=# &nbsp; CREATE FUNCTION bar2() RETURNS foo2 AS $$
postgres$# &nbsp; DECLARE
postgres$# &nbsp; &nbsp; &nbsp; r foo2 := ROW(1, 'hello');
postgres$# &nbsp; BEGIN
postgres$# &nbsp; &nbsp; &nbsp; ALTER TYPE foo2 ALTER ATTRIBUTE b TYPE INT;
postgres$# &nbsp; &nbsp; &nbsp; RETURN r;
postgres$# &nbsp; END;
postgres$# &nbsp; $$ LANGUAGE plpgsql;
CREATE FUNCTION
postgres=# &nbsp; SELECT bar2();
ERROR: &nbsp;invalid input syntax for type integer: "hello"
CONTEXT: &nbsp;PL/pgSQL function bar2() line 6 at RETURN
postgres=# DROP FUNCTION bar();
DROP FUNCTION
postgres=# &nbsp; DROP FUNCTION bar1();
DROP FUNCTION
postgres=# &nbsp; DROP FUNCTION bar2();
DROP FUNCTION
postgres=# &nbsp; DROP TYPE IF EXISTS foo CASCADE;
DROP TYPE
postgres=# &nbsp; DROP TYPE IF EXISTS foo1 CASCADE;
DROP TYPE
postgres=# &nbsp; DROP TYPE IF EXISTS foo2 CASCADE;
DROP TYPE
postgres=# quit

Regards,
Surya Poondla