Hello Andres,
14.09.2021 08:05, Andres Freund wrote:
>
>> With LLVM 9 on the same Centos 7 I don't get such segfault. Also it
>> doesn't happen on different OSes with LLVM 7.
> That just like an llvm bug to me. Rather than the usage issue addressed in this thread.
But Justin seen this strangeness too:
>
> I couldn't crash on ubuntu either, so maybe they have a patch which
> fixes this,
> or maybe RH applied a patch which caused it...
>
The script that Justin presented:
> postgres=# CREATE TABLE t AS SELECT i FROM generate_series(1,999999)i;
> VACUUM ANALYZE t;
> postgres=# SET client_min_messages=debug; SET statement_timeout=333;
> SET jit_above_cost=0; SET jit_optimize_above_cost=-1; SET
> jit_inline_above_cost=-1; explain analyze SELECT sum(i) FROM t a
> NATURAL JOIN t b;
causes the server crash on Centos 7 with LLVM 7 (even with the fix
applied) and doesn't crash with LLVM 9 (I used llvm-toolset-9* and
devtoolset-9* packages from
https://buildlogs.centos.org/c7-llvm-toolset-9.0.x86_64/ and
https://buildlogs.centos.org/c7-devtoolset-9.x86_64/ repositories).
The another script:
>
> python3 -c "import pg; db=pg.DB('dbname=postgres host=/tmp
> port=5678'); db.query('SET jit_above_cost=0; SET
> jit_inline_above_cost=-1; SET jit=on; SET client_min_messages=debug');
> db.query('begin'); db.query_formatted('SELECT 1 FROM
> generate_series(1,99)a WHERE a=%s', [1], inline=False);"
>
also causes the server crash with LLVM 7, and doesn't crash with LLVM 9.
So I wonder, isn't the fixed usage issue specific to LLVM 7, which is
not going to be supported as having some bugs?
Best regards,
Alexander
