BUG #14864: PostgresSQL script is skipping to process random records

The following bug has been logged on the website:

Bug reference: 14864
Logged by: bharti bhandari
Email address: bharti(dot)bhandari(at)gmail(dot)com
PostgreSQL version: 9.4.10
Operating system: Heroku Env
Description:

We are using salesforce heroku connection in our project.
We have an object in Salesforce named WorkRota ( It captures
resource/contact availability for a particular time period ) and our goal
was to split every workrota in 10 - 10 minutes slot. We store these 10-10
minutes slots in another table in Postgres named ContactAvailability and we
wrote a stored procedure for the conversion process.

There is one more object from Salesforce to Heroku named Assignment is used
for making the contactavailality unavailable.

The problem is when the records comes in bulk then the script is skipping
random record. The behaviour is not frequent as well.

Please let me know if any one can help. Happy come on GTM/ Call to explain
in detail.