Enable reWriteBatchedInserts in sonar-db-copy to improve Postgres performance

 a significant performance gain was due to enabling reWriteBatchedInserts :

• reWriteBatchedInserts = booleanThis will change batch inserts from insert into foo (col1, col2, col3) values (1,2,3) into insert into foo (col1, col2, col3) values (1,2,3), (4,5,6) this provides 2-3x performance improvement

So, combining, similar INSERT statements into one BIG INSERT (limiting the network packets etc and multiple transactions overhead on db side).

According to what the customer stated in the ticket 2

performance went from avg. 2000 rows per second to 15000-20000

It can be set as a JDBC connection string param however maybe enabling this, in the DBCopy context, at code level makes sense as well.