Why I am not able to find any database tables of survey data in collect schema in PostgreSQL database?

Hi Milan,
The table you are looking for is called ofc_record (the prefix ofc stays for Open Foris Collect...), under the schema Collect. Every record (a cluster or a plot, depending on your survey...) corresponds to a row in that table. You can see different interesting columns... key1, key2, key3 contain the values of the key attributes and will help you to find a record. Data1 and data2 contain the actual collected data. They are binary columns and the only way to read the real data is to use Collect. This can be seen as a limit, because the only way to read and modify the data is to use the application, but it makes the process of reading and writing of the records very fast... even if we cannot guarantee that we won't change the way the data is stored into the database soon... This fact of having the data in a sort of "black box" sometimes makes the things more difficult to manage even for us.
If you need to see and work with the raw data, you can use Collect to export it to CSV or to a relational database.
I hope that now everything looks a bit clearer.
For more information about the structure of the database, please have a look to the documentation we have on GitHub.
Many thanks,
Open Foris Team