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strLength assertion on join and concat #3311

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

strLength assertion on join and concat #3311

monetdb-team opened this issue Nov 30, 2020 · 0 comments
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bug Something isn't working normal SQL

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Date: 2013-06-20 11:13:44 +0200
From: @swingbit
To: SQL devs <>
Version: 11.15.3 (Feb2013-SP1)
CC: @mlkersten, @njnes

Last updated: 2013-09-27 13:47:16 +0200

Comment 18866

Date: 2013-06-20 11:13:44 +0200
From: @swingbit

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.93 Safari/537.36
Build Identifier:

I could not really pinpoint the exact cause for this bug, however I have a reproducible test and a few remarks.

The query triggering the bug:

SELECT x.idstr, '{ "pid":"'||x.idstr||'" }' as json
FROM y, x
WHERE y.subject=x.id;

The assertion: src/monetdb5/modules/atoms/str.c:1357: strLength: Assertion `l <2147483647' failed.

gdb sais:
Thread 10 (Thread 0x7f99a5a5d700 (LWP 1209)):
0 0x0000003d8dc35ba5 in raise () from /lib64/libc.so.6
1 0x0000003d8dc37358 in abort () from /lib64/libc.so.6
2 0x0000003d8dc2e972 in __assert_fail_base () from /lib64/libc.so.6
3 0x0000003d8dc2ea22 in __assert_fail () from /lib64/libc.so.6
4 0x00007f99c0058743 in strLength (res=0x7f99a5a5c430, s=0x7f998418a7f0 "{ "pid":"\310\064" }") at /opt/spinque/MonetDBServer/MonetDB.Spinque_Feb2013/src/monetdb5/modules/atoms/str.c:1357
5 0x00007f99b77ea23f in bat_max_strlength (b=0x7f9984003e50) at /opt/spinque/MonetDBServer/MonetDB.Spinque_Feb2013/src/sql/backends/monet5/sql_result.c:219
6 0x00007f99b77ef6a4 in export_length (s=0x7f99a0004b00, mtype=12, eclass=4, digits=0, scale=0, tz=0, bid=4194, p=0x0) at /opt/spinque/MonetDBServer/MonetDB.Spinque_Feb2013/src/sql/backends/monet5/sql_result.c:1189
7 0x00007f99b77f06ba in mvc_export_head (m=0x7f9998005470, s=0x7f99a0004b00, res_id=2, only_header=1) at /opt/spinque/MonetDBServer/MonetDB.Spinque_Feb2013/src/sql/backends/monet5/sql_result.c:1477
8 0x00007f99b77f0aff in mvc_export_result (m=0x7f9998005470, s=0x7f99a0004b00, res_id=2) at /opt/spinque/MonetDBServer/MonetDB.Spinque_Feb2013/src/sql/backends/monet5/sql_result.c:1546
...

Note that:

  • The string "pid":"\310\064", for which strLength fails, DOES NOT exist in the data. It must be the wrong outcome of previous intermediate results.
  • removing the join with y, it works
  • removing the concatenation bit, it works
  • removing the first column from the target list, it works
  • disabling mitosis, it works
  • with less data, it works

Reproducible: Always

Actual Results:

/src/monetdb5/modules/atoms/str.c:1357: strLength: Assertion `l <2147483647' failed.

changeset: 47997:918b41d7564d
branch: Feb2013
parent: 47995:223fee7295a2
user: Hannes Muehleisen hannes@cwi.nl
date: Wed Jun 19 15:23:34 2013 +0200
summary: Post release build.

$ mserver5 --version
MonetDB 5 server v11.15.10 (64-bit, 64-bit oids)
This is an unreleased version
Copyright (c) 1993-July 2008 CWI
Copyright (c) August 2008-2013 MonetDB B.V., all rights reserved
Visit http://www.monetdb.org/ for further information
Found 15.6GiB available memory, 8 available cpu cores
Libraries:
libpcre: 8.31 2012-07-06 (compiled with 8.31)
openssl: OpenSSL 1.0.1e 11 Feb 2013 (compiled with OpenSSL 1.0.1e-fips 11 Feb 2013)
libxml2: 2.9.1 (compiled with 2.9.1)
Compiled by: roberto@photon.spinque.com (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 18867

Date: 2013-06-20 11:16:21 +0200
From: @swingbit

I cannot make the test with real data public. I can send the file if you ask me by email.

Comment 18869

Date: 2013-06-20 11:41:41 +0200
From: @mlkersten

Could you run it with valgrind? It seems there might be an issue much earlier in the process.

Comment 18875

Date: 2013-06-22 15:46:53 +0200
From: @njnes

Fixed. This was a very interesting bug. The problem was caused by a concurrent mat pack which triggered a BATappend, which again called string_insert_bat.
That string_insert_bat has a nice optimization for the case when we don't eliminate duplicates anymore, ie its simply copies the var-heap.
This is all fine, but the bun (offset) copying was done by disabling
the varsized atom marker. Which caused the concurrent string concat function to see the offset as strings.

@monetdb-team monetdb-team added bug Something isn't working normal SQL labels Nov 30, 2020
@sjoerdmullender sjoerdmullender added this to the Ancient Release milestone Feb 7, 2022
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