July 2016 - users-list

Is there any scan sharing technique in MonetDB?
by Xu,Wenjian 07 Jul '16

07 Jul '16

Hi all, I understand that MonetDB would recycle intermediate results to accelerate subsequent OLAP queries that involve common sub-queries as previous ones. I am wondering that, 1. Does MonetDB implement any scan sharing techniques (or generally, multi-query optimization techniques) in the context of concurrent workloads? For example, two concurrent queries Q1 and Q2 both require scanning column X. Is it possible for their query plans to share the scan operation? 2. If no, what is the reason? too complex to implement? or any reason related to MonetDB's execution paradigm that prevents such sharing techniques? Any comments would be helpful, thanks. Best regards, Wenjian

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R UDFs
by Anderson, David B 06 Jul '16

06 Jul '16

All, Quick question, how many R interpreters are running within MonetDB if you are using R UDFs? Is there a single shared interpreter or are there multiple copies running? Thanks, Dave

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DATABASE NOT STARTING
by Ariel Abadi 04 Jul '16

04 Jul '16

Guys! Im desperate... the DB is not starting anymore... Can someone help me? Im starting the DB but I receive the following msg: starting database 'sb_traf'... FAILED start: starting 'sb_traf' failed: database 'sb_traf' appears to shut itself down after starting, check monetdbd's logfile for possible hints This is part of the log... maybe somebody has a clue. 2016-07-02 22:15:30 MSG merovingian[28268]: proxying client static.10-10-10-225.clients.your-server.de:47462 for database 'sb_traf' to mapi:monetdb:///opt/monetdb/CUSTOMERnew/sb_traf/.mapi.sock?database=sb_traf 2016-07-02 22:15:30 MSG merovingian[28268]: target connection is on local UNIX domain socket, passing on filedescriptor instead of proxying 2016-07-02 22:15:30 MSG merovingian[28268]: proxying client static.10-10-10-225.clients.your-server.de:47463 for database 'sb_traf' to mapi:monetdb:///opt/monetdb/CUSTOMERnew/sb_traf/.mapi.sock?database=sb_traf 2016-07-02 22:15:30 MSG merovingian[28268]: target connection is on local UNIX domain socket, passing on filedescriptor instead of proxying 2016-07-02 22:20:29 MSG merovingian[28268]: proxying client static.10-10-10-225.clients.your-server.de:47726 for database 'sb_traf' to mapi:monetdb:///opt/monetdb/CUSTOMERnew/sb_traf/.mapi.sock?database=sb_traf 2016-07-02 22:20:29 MSG merovingian[28268]: target connection is on local UNIX domain socket, passing on filedescriptor instead of proxying 2016-07-02 22:20:29 MSG merovingian[28268]: database 'sb_traf' (28351) was killed by signal SIGSEGV 2016-07-02 22:20:36 MSG merovingian[28268]: starting database 'sb_traf', up min/avg/max: 11s/1d/3w, crash average: 1.00 0.40 0.50 (69-25=44) 2016-07-02 22:20:36 MSG sb_traf[29578]: arguments: /usr/bin/mserver5 --dbpath=/opt/monetdb/CUSTOMERnew/sb_traf --set merovingian_uri=mapi:monetdb://CUSTOMER-monetbd:54321/sb_traf --set mapi_open=false --set mapi_port=0 --set mapi_usock=/opt/monetdb/CUSTOMERnew/sb_traf/.mapi.sock --set monet_vault_key=/opt/monetdb/CUSTOMERnew/sb_traf/.vaultkey --set gdk_nr_threads=8 --set max_clients=64 --set sql_optimizer=default_pipe --set monet_daemon=yes 2016-07-02 22:20:36 MSG sb_traf[29578]: # MonetDB 5 server v11.21.19 "Jul2015-SP4" 2016-07-02 22:20:36 MSG sb_traf[29578]: # Serving database 'sb_traf', using 8 threads 2016-07-02 22:20:36 MSG sb_traf[29578]: # Compiled for x86_64-redhat-linux-gnu/64bit with 64bit OIDs and 128bit integers dynamically linked 2016-07-02 22:20:36 MSG sb_traf[29578]: # Found 20.000 GiB available main-memory. 2016-07-02 22:20:36 MSG sb_traf[29578]: # Copyright (c) 1993-July 2008 CWI. 2016-07-02 22:20:36 MSG sb_traf[29578]: # Copyright (c) August 2008-2015 MonetDB B.V., all rights reserved 2016-07-02 22:20:36 MSG sb_traf[29578]: # Visit http://www.monetdb.org/ for further information 2016-07-02 22:20:36 MSG sb_traf[29578]: # Listening for UNIX domain connection requests on mapi:monetdb:///opt/monetdb/CUSTOMERnew/sb_traf/.mapi.sock 2016-07-02 22:20:36 MSG sb_traf[29578]: # Start processing logs sql/sql_logs version 52200 2016-07-02 22:20:36 MSG sb_traf[29578]: # Start reading the write-ahead log 'sql_logs/sql/log.81841' 2016-07-02 22:20:36 MSG sb_traf[29578]: # Finished reading the write-ahead log 'sql_logs/sql/log.81841' 2016-07-02 22:20:36 MSG sb_traf[29578]: # Finished processing logs sql/sql_logs 2016-07-02 22:20:36 MSG merovingian[28268]: database 'sb_traf' (29578) was killed by signal SIGSEGV 2016-07-02 22:20:36 ERR merovingian[28268]: client error: database 'sb_traf' appears to shut itself down after starting, check monetdbd's logfile for possible hints 2016-07-02 22:20:37 MSG merovingian[28268]: starting database 'sb_traf', up min/avg/max: 11s/1d/3w, crash average: 1.00 0.50 0.50 (70-25=45) 2016-07-02 22:20:37 MSG sb_traf[29582]: arguments: /usr/bin/mserver5 --dbpath=/opt/monetdb/CUSTOMERnew/sb_traf --set merovingian_uri=mapi:monetdb://CUSTOMER-monetbd:54321/sb_traf --set mapi_open=false --set mapi_port=0 --set mapi_usock=/opt/monetdb/CUSTOMERnew/sb_traf/.mapi.sock --set monet_vault_key=/opt/monetdb/CUSTOMERnew/sb_traf/.vaultkey --set gdk_nr_threads=8 --set max_clients=64 --set sql_optimizer=default_pipe --set monet_daemon=yes 2016-07-02 22:20:37 MSG sb_traf[29582]: # MonetDB 5 server v11.21.19 "Jul2015-SP4" 2016-07-02 22:20:37 MSG sb_traf[29582]: # Serving database 'sb_traf', using 8 threads 2016-07-02 22:20:37 MSG sb_traf[29582]: # Compiled for x86_64-redhat-linux-gnu/64bit with 64bit OIDs and 128bit integers dynamically linked 2016-07-02 22:20:37 MSG sb_traf[29582]: # Found 20.000 GiB available main-memory. 2016-07-02 22:20:37 MSG sb_traf[29582]: # Copyright (c) 1993-July 2008 CWI. 2016-07-02 22:20:37 MSG sb_traf[29582]: # Copyright (c) August 2008-2015 MonetDB B.V., all rights reserved 2016-07-02 22:20:37 MSG sb_traf[29582]: # Visit http://www.monetdb.org/ for further information 2016-07-02 22:20:37 MSG sb_traf[29582]: # Listening for UNIX domain connection requests on mapi:monetdb:///opt/monetdb/CUSTOMERnew/sb_traf/.mapi.sock 2016-07-02 22:20:37 MSG sb_traf[29582]: # Start processing logs sql/sql_logs version 52200 2016-07-02 22:20:37 MSG sb_traf[29582]: # Start reading the write-ahead log 'sql_logs/sql/log.81841' 2016-07-02 22:20:37 MSG sb_traf[29582]: # Finished reading the write-ahead log 'sql_logs/sql/log.81841' 2016-07-02 22:20:37 MSG sb_traf[29582]: # Finished processing logs sql/sql_logs 2016-07-02 22:20:37 MSG merovingian[28268]: database 'sb_traf' (29582) was killed by signal SIGSEGV 2016-07-02 22:20:37 ERR merovingian[28268]: client error: database 'sb_traf' appears to shut itself down after starting, check monetdbd's logfile for possible hints

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python map
by Stefano Fioravanzo 04 Jul '16

04 Jul '16

Hello, I have a long and complex embedded python function. This function depends on the single rows of the input columns, so I would like to parallelize it. I’ve read about the post on embedded python and python_map. I understand that using python_map should automatically split (in a not specified way) the input columns and fire different (how many?) python processes executing on their input slice. Finally it should pack all the partial results. Well, I have tried to use python_map, but nothing different happened. Is there something more I have to do apart from setting LANGUAGE PYTHON_MAP? Regards, Stefano

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