Something does not make sense, when creating a new install you have the option of Hollaex Mainnet, Hollaex Testnet, and Custom Network, linking to the Hollaex Mainnet you get all the liquidity of the assets and pairs for trading, these are synched to dash.hollaex.com.
All the documentation and comments state when you create a DIY you can avoid the hollaex network and run everything locally for your own liquidity, but, when you create a custom asset via the mainnet it syncs to dash.hollaex.com, and presume the OTC deal also does the same, the postgres database is never used, we looked in the docker container and there is nothing there.
According to the comments in the forum you can make a DIY exchange with no connection to the hollaex network, how because we tried and it does not work.
When you create an asset on the mainnet there is an approval process and XHT staking, there are fourm posts that you do not need to go through this process, but even the OTC are synced to the dash, where do you create an asset in the exchange off the network bypassing the approval, basically a Darkpool.
It appears if you choose mainnet then everything is synched to the dash, it is not clear but seems the only way to use the local postgres database for assets/markets is to have a custom network, where is the information about activating this.