[Monetdb-developers] Parallel insertions in monetdb table - some records do not insert

Martin Kersten Martin.Kersten at cwi.nl
Mon Jun 14 20:46:38 CEST 2010


Hello,

This 'issue' is raised several times,e.g.

http://www.mail-archive.com/monetdb-developers@lists.sourceforge.net/msg02219.html

Google: monetdb optimistic concurrency

for more references about how optimistic concurrency control
can not support your intended OLTP behavior. You probably have
to serialize the updates through a master or use independent
servers.

regards, Martin

kss ram wrote:
> Hello Everyone!
> 
> Brief Overview of the issue
> 
> 1. Sample Data that erlang program tries to insert in monetdb
>  
> {data,
>    [{"a","string"}, {"b","string"}], %% a,b are column names
> [         
>    [{"a","a1"}, {"b","b1"}], %% key, value pair of the data - 
> {columnname, data}
>    [{"a","a2"}, {"b","b2"}],
>    [{"a","a3"}, {"b","b3"}],
>    [{"a","a4"}, {"b","b4"}],
>    [{"a","a5"}, {"b","b5"}],
>    [{"a","a6"}, {"b","b6"}],
>    [{"a","a7"}, {"b","b7"}],
>    [{"a","a8"}, {"b","b8"}],
>    [{"a","a9"}, {"b","b9"}],
>    [{"a","a10"}, {"b","b10"}],
>    [{"a","a11"}, {"b","b11"}]
> ],      
>    {"no_of_records","12"}
> }
> 
> 2. no of threads/processes that would do parallel inserts would be 
> determined by the thread size i.e how many of records the thread would 
> insert, if say 5 records then 3 threads, if 3 records then 4 threads.
> 
> 3. in order to connect to monetdb from erlang, the monetdb ODBC driver 
> is specified in ODBCConfig utility of ubuntu, driver file is 
> /usr/lib/libMonetODBC.so
> 
> 4. threads are successfully created and the ODBC module quits 
> successfully after inserting in the erlang program, but when we look in 
> the monetdb table, some of the rows get missed, for example row from 1 
> to 11 get inserted without row 3 or 4 getting inserted.
> 
> could this be a problem with the ODBC driver?, am I missing any 
> configuration?, any help would be deeply appreciated.
> 
> Thank you,
> 
> Ram.
> 
> 
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