Optimise Hibernate Settings

[arya-hemanshu]

Description

Currently all the hibernate options are set to default and it would be good if we could change a few of them to boost the performance of DC and to get the best out of Hibernate.

e.g.
In FixedValueUtils.java we are flushing every 20 records, however we are not setting batch_size anywhere to 20, and jdbc default batch size is 5.

If we up the batch size to 1000 and flush every 1000 records it will noticeably improve DC's performance, in some cases 3 times faster.

But that also means that incase transaction fails we loose 1000 records, instead of 5. Thus need to take care of all those scenarios as well.

Error log

NA

[lorenaqendro]

Consider the changes introduces by #552 changing the batch size to 50.