Bugs item #2771052, was opened at 2009-04-17 18:55
Message generated for change (Comment added) made by mlkersten
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Category: SQL/Core
Group: SQL "stable"
>Status: Open
>Resolution: Accepted
Priority: 5
Private: No
Submitted By: Stefan Manegold (stmane)
>Assigned to: Martin Kersten (mlkersten)
Summary: M5/SQL: parallel bulk-load (copy into) incorrect

Initial Comment:
With a simple CSV file containing 100000000 rows, each holding just a single 
'1', I get the following when running a (default) 4-threaded mserver5 on my 
4-core machine:

$ mserver5 --dbinit='include sql;'
# MonetDB server v5.10.3, based on kernel v1.28.3
# Serving database 'demo', using 4 threads
# Compiled for x86_64-unknown-linux-gnu/64bit with 64bit OIDs dynamically linked
# Copyright (c) 1993-July 2008 CWI.
# Copyright (c) August 2008-2009 MonetDB B.V., all rights reserved
# Visit http://monetdb.cwi.nl/ for further information
#warning: please don't forget to set your vault key!
#(see 
/ufs/manegold/_/scratch0/Monet/Testing/Stable/prefix.--enable-strict_--disable-optimize_--enable-debug_--enable-assert/etc/monetdb5.conf)
# Listening for connection requests on mapi:monetdb://127.0.0.1:50000/
# MonetDB/SQL module v2.28.3 loaded

$ mclient -lsql
sql>create table i0 (a integer);
0 tuples
sql>create table i1 (a integer);
0 tuples
sql>create table i2 (a integer);
0 tuples
sql>create table i3 (a integer);
0 tuples
sql>create table i4 (a integer);
0 tuples
sql>create table i5 (a integer);
0 tuples
sql>create table i6 (a integer);
0 tuples
sql>create table i7 (a integer);
0 tuples
sql>create table i8 (a integer);
0 tuples

$ mclient -lsql
sql>copy 1 records into i0 from '/tmp/1.csv';
Rows affected 1
sql>copy 10 records into i1 from '/tmp/1.csv';
Rows affected 10
sql>copy 100 records into i2 from '/tmp/1.csv';
Rows affected 100
sql>copy 1000 records into i3 from '/tmp/1.csv';
Rows affected 1000
sql>copy 10000 records into i4 from '/tmp/1.csv';
Rows affected 40000
sql>copy 100000 records into i5 from '/tmp/1.csv';
Rows affected 400000
sql>copy 1000000 records into i6 from '/tmp/1.csv';
Rows affected 4000000
sql>copy 10000000 records into i7 from '/tmp/1.csv';
Rows affected 40000000
sql>copy 100000000 records into i8 from '/tmp/1.csv';
Rows affected 100000000

(Mind the '4's where '1's are expected.)

The problem is analogously reproducible with `mserver5 --set gdk_nr_threads=3` 
& `mserver5 --set gdk_nr_threads=2`;
bulk-loading works fine with `mserver5 --set gdk_nr_threads=1`.


----------------------------------------------------------------------

>Comment By: Martin Kersten (mlkersten)
Date: 2009-08-09 13:15

Message:
The bug should have been left open, as it is a BUG part of at least two
releases and should be fixed.

----------------------------------------------------------------------

Comment By: Stefan Manegold (stmane)
Date: 2009-07-31 06:54

Message:
Clean-up:
This one is no longer relevant, as parallel bulk loading has been disabled
due to inherent design flaws:
===================================================================
2009/05/25 - sjoerd: MonetDB5/src/modules/mal/tablet.mx,1.194.2.3
Set nway to 1 since parallel import *cannot* work with the current
implementation: there is an inherent bug when the number of records to
be imported is smaller than what is available in the file.
===================================================================


----------------------------------------------------------------------

Comment By: Stefan Manegold (stmane)
Date: 2009-04-17 19:13

Message:
added test in
sql/src/test/BugTracker-2009/Tests/parallel_bulk-load.SF-2771052.{unpack_csv,test}.*
(Feb2009 release branch)


----------------------------------------------------------------------

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