Sqlitelogictest crash in complex SQL query

[monetdb-team]

Date: 2017-06-26 11:11:10 +0200
From: @PedroTadim
To: SQL devs <>
Version: -- development
CC: @njnes

Last updated: 2017-10-26 14:01:28 +0200

Comment 25394

Date: 2017-06-26 11:11:10 +0200
From: @PedroTadim

User-Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.109 Safari/537.36
Build Identifier:

Mserver takes too long processing a single but complex SQL query. After a certain time, it receives a SIGKILL signal.

Reproducible: Always

Steps to Reproduce:

1. SELECT DISTINCT 8 * + + CASE + NULLIF ( - - CASE - ( 52 ) WHEN + 18 - - COUNT ( * ) THEN + 4 WHEN + + 93 - - ( - 40 ) THEN - - 1 * 27 * MIN ( DISTINCT - 85 ) + - - 29 * - + CASE - CASE - 66 WHEN - + 87 / 51 THEN 25 * 78 END WHEN - 12 * - 38 / + - 64 * - - CASE - - 61 WHEN + - 84 + 83 + + 36 * NULLIF ( - 46, - 21 ) * 21 + - 18 + - 21 THEN + 8 * 45 WHEN + 40 THEN NULL END * 7 THEN NULL WHEN - 8 THEN SUM ( + 62 ) * 44 WHEN - ( - ( + ( 6 ) ) ) THEN + 91 + + 38 ELSE NULL END END, + 57 ) WHEN - CAST ( NULL AS INTEGER ) THEN ( 46 ) ELSE NULL END * - 77;

Actual Results:

The server receives a SIGKILL signal after a while.

Expected Results:

A single NULL value.

The merovingian.log only shows the SIGKILL line:

2017-06-26 10:49:42 MSG merovingian[2946]: database 'db' (26839) was killed by signal SIGKILL

Comment 25529

Date: 2017-07-31 09:58:36 +0200
From: @sjoerdmullender

Something goes seiously wrong in the SQL optimizer. I stopped the execution at a point where the MAL variable stack was 3853412 entries big and still growing. That seems excessive for this query.

Comment 25589

Date: 2017-08-18 13:37:33 +0200
From: MonetDB Mercurial Repository <>

Changeset 484ca02b0773 made by Pedro Ferreira pedro.ferreira@monetdbsolutions.com in the MonetDB repo, refers to this bug.

For complete details, see https//devmonetdborg/hg/MonetDB?cmd=changeset;node=484ca02b0773

Changeset description:

Added test for Bug #6335

Comment 25637

Date: 2017-09-17 09:26:27 +0200
From: @njnes

fixed crash, we now rewrite large expressions into smaller onces (which solves
the explosion when rewriting for division by zero and similar problems)

Comment 25641

Date: 2017-09-17 18:01:40 +0200
From: MonetDB Mercurial Repository <>

Changeset 9ccae5c8d830 made by Niels Nes niels@cwi.nl in the MonetDB repo, refers to this bug.

For complete details, see https//devmonetdborg/hg/MonetDB?cmd=changeset;node=9ccae5c8d830

Changeset description:

re-implemented declared tables, to solve the side-effect bug #6397.

also lots of fixes for the sqllitelogistest_case bug #6335 (doesn't
crash (or run out of memory) anymore).

Comment 25662

Date: 2017-09-20 12:20:31 +0200
From: @PedroTadim

The crash does not happen anymore, but a MAL error occurs:

!TypeException:user.main[236]:'calc.' undefined in: X_26992:sht := calc.(X_26990:int, X_26991:bte);

So I guess the calc operations are not implemented across numeric data types.

Comment 25724

Date: 2017-10-15 18:57:27 +0200
From: @njnes

The function type problem was caused in the inplace type casting code.

Comment 25725

Date: 2017-10-15 20:25:51 +0200
From: MonetDB Mercurial Repository <>

Changeset b1efe52241ae made by Niels Nes niels@cwi.nl in the MonetDB repo, refers to this bug.

For complete details, see https//devmonetdborg/hg/MonetDB?cmd=changeset;node=b1efe52241ae

Changeset description:

fixed bug #6335, ie don't do inplace conversions on shared atoms