Codegen does not support certain kind of selects on scalar subqueries

[monetdb-team]

Date: 2016-11-09 11:10:43 +0100
From: Dean De Leo <>
To: SQL devs <>
Version: -- development
CC: @njnes

Last updated: 2016-12-21 13:07:22 +0100

Comment 24661

Date: 2016-11-09 11:10:43 +0100
From: Dean De Leo <>

User-Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36
Build Identifier:

The server crashes due to an assertion when issuing certain kind of scalar subqueries.

Reproducible: Always

Steps to Reproduce:

1. Load the attached schema
2. Issue the attached query
3. Assertion hit

Actual Results:

See attached backtrace

Expected Results:

Server failures are bad. Assuming they should never occur.

Comment 24662

Date: 2016-11-09 11:11:32 +0100
From: Dean De Leo <>

Created attachment 497
DBMS schema

Attached file: schema.sql (application/sql, 7731 bytes)
Description: DBMS schema

Comment 24663

Date: 2016-11-09 11:11:53 +0100
From: Dean De Leo <>

Created attachment 498
Repro query (query3.sql)

Attached file: query3.sql (application/sql, 520 bytes)
Description: Repro query (query3.sql)

Comment 24664

Date: 2016-11-09 11:12:24 +0100
From: Dean De Leo <>

Created attachment 499
Backtrace

Attached file: backtrace3.txt (text/plain, 4271 bytes)
Description: Backtrace

Comment 24665

Date: 2016-11-09 11:12:45 +0100
From: Dean De Leo <>

On Linux, tip of the default branch, debug build, empty tables.

Comment 24672

Date: 2016-11-09 23:07:12 +0100
From: MonetDB Mercurial Repository <>

Changeset bfc05edc1fa1 made by Niels Nes niels@cwi.nl in the MonetDB repo, refers to this bug.

For complete details, see http//devmonetdborg/hg/MonetDB?cmd=changeset;node=bfc05edc1fa1

Changeset description:

fixes for bugs 6114, 6115, 6116 and 6117

improved dead code elimination for cases with references to sub queries (ie its a dag)
push simple select like expressions downs

split_project test is added here but only crashes in the dec2016/default.

Comment 24676

Date: 2016-11-10 08:06:08 +0100
From: @njnes

fixed a problem with semijoin and select expressions (ie they get pushed down more now)