All, I am seeing odd behavior with Remote/Merge tables. I have a pair of servers, one of which has a merge table that combines 12 remote & 12 local tables (24 total) into a single large table. Queries from the main server on the merge table cause the remote server to crash with a SIGSEGV. If I create a merge table which only contains the remote tables (loan2) the remote server doesn't crash, but I get different responses for the same query in the same session: /opt/flash1/gnmaloan$ mclient -d loan Welcome to mclient, the MonetDB/SQL interactive terminal (Jul2015-SP4) Database: MonetDB v11.21.19 (Jul2015-SP4), 'mapi:monetdb://malxcs1p:50000/loan' Type \q to quit, \? for a list of available commands auto commit mode: on sql>select asofdate,sum(balance),count(loanseqnum) from loan2 group by asofdate; (mapi:monetdb://monetdb@malxcs2p/loan) unable to find sys.loan201402(loanseqnum) sql>select asofdate,sum(balance),count(loanseqnum) from loan2 group by asofdate; +------------+--------------------------+----------+ | asofdate | L1 | L2 | +============+==========================+==========+ | 2014-03-01 | 124075979043384 | 9177029 | | 2014-05-01 | 1.2634454179935e+14 | 9264814 | | 2014-07-01 | 126798740013672 | 9335352 | | 2014-09-01 | 126526301326951 | 9407070 | | 2014-11-01 | 1.2604434513281e+14 | 9478920 | | 2015-01-01 | 1.2644932715183e+14 | 9529639 | | 2015-03-01 | 127602153039423 | 9579604 | | 2015-05-01 | 126615476286119 | 9654842 | | 2015-07-01 | 125415108251273 | 9756258 | | 2015-09-01 | 124427385478338 | 9855118 | | 2015-11-01 | 126150962049943 | 9945919 | | 2016-01-01 | 129313947667802 | 10011556 | +------------+--------------------------+----------+ 12 tuples (0.9s) The only thing I see in the crashing server's log is: 2016-04-25 16:55:50 MSG merovingian[28226]: target connection is on local UNIX domain socket, passing on filedescriptor instead of proxying 2016-04-25 16:55:50 MSG merovingian[28226]: database 'loan' (2706) was killed by signal SIGSEGV 2016-04-25 16:56:37 MSG merovingian[28226]: starting database 'loan', up min/avg/max: 2m/1h/2h, crash average: 1.00 0.90 0.33 (12-2=10) 2016-04-25 16:56:37 MSG loan[28022]: arguments: /opt/mr/monetdb/bin/mserver5 --dbpath=/opt/flash2/monetdb2/loan --set merovingian_uri=mapi:monetdb://malxcs2p:50000/loan --set mapi_open=false --set mapi_port=0 --set mapi_usock=/opt/flash2/monetdb2/loan/.mapi.sock --set monet_vault_key=/opt/flash2/monetdb2/loan/.vaultkey --set gdk_nr_threads=24 --set max_clients=64 --set sql_optimizer=default_pipe --set monet_daemon=yes Not sure where to start debugging this. I guess I will see if this still occurs with a small number of rows in the base tables. Thanks, Dave