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identifier ambiguous when grouping and selecting the same column twice #6207

monetdb-team opened this issue Nov 30, 2020 · 0 comments


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@monetdb-team monetdb-team commented Nov 30, 2020

Date: 2017-02-09 10:59:42 +0100
From: @swingbit
To: SQL devs <>
Version: 11.25.5 (Dec2016-SP1)
CC: @njnes

Last updated: 2017-10-26 14:01:33 +0200

Comment 24993

Date: 2017-02-09 10:59:42 +0100
From: @swingbit

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36
Build Identifier:

Starting from this, which works fine :

sql>select name,name from sys.functions group by name limit 2;
| name | name |
| mbr_overlap | mbr_overlap |
| mbr_above | mbr_above |
2 tuples (2.994ms)

The following, though pointless, should be allowed (group twice on the same column):

sql>select name, name from sys.functions group by name,name limit 2;
SELECT: identifier 'name' ambiguous

By using table qualifiers, it works again:

sql>select, from sys.functions AS f group by name,name limit 2;
| name | name |
| mbr_overlap | mbr_overlap |
| mbr_above | mbr_above |
2 tuples (4.035ms)

Not a serious issue, but table qualifiers should not be needed. The second attempt has no ambiguous identifiers, as far as I can see.

Reproducible: Always

$ mserver5 --version
MonetDB 5 server v11.25.6 (64-bit, 128-bit integers)
This is an unreleased version
Copyright (c) 1993-July 2008 CWI
Copyright (c) August 2008-2017 MonetDB B.V., all rights reserved
Visit for further information
Found 15.6GiB available memory, 8 available cpu cores
libpcre: 8.40 2017-01-11 (compiled with 8.40)
openssl: OpenSSL 1.0.2j 26 Sep 2016 (compiled with OpenSSL 1.0.2j-fips 26 Sep 2016)
libxml2: 2.9.3 (compiled with 2.9.3)
Compiled by: (x86_64-unknown-linux-gnu)
Compilation: gcc -g -Werror -Wall -Wextra -W -Werror-implicit-function-declaration -Wpointer-arith -Wdeclaration-after-statement -Wundef -Wformat=2 -Wno-format-nonliteral -Winit-self -Winvalid-pch -Wmissing-declarations -Wmissing-format-attribute -Wmissing-prototypes -Wold-style-definition -Wpacked -Wunknown-pragmas -Wvariadic-macros -fstack-protector-all -Wstack-protector -Wpacked-bitfield-compat -Wsync-nand -Wjump-misses-init -Wmissing-include-dirs -Wlogical-op -Wunreachable-code
Linking : /usr/bin/ld -m elf_x86_64

Comment 25738

Date: 2017-10-16 08:55:38 +0200
From: MonetDB Mercurial Repository <>

Changeset 02c08819c11f made by Niels Nes in the MonetDB repo, refers to this bug.

For complete details, see https//devmonetdborg/hg/MonetDB?cmd=changeset;node=02c08819c11f

Changeset description:

fixed bug #6207, remove duplicate expressions in group by list.
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