VLDB is using Slack (a chat program) for asynchronous communication, questions that go past the Q&A, and other random background chatter during the conference. Every session, sponsor, and workshop has a dedicated room in our Slack workspace. You can find links to these in the interactive VLDB program.
Before using slack you will need to sign up here: SHOHEI_REPLACE_ME_WITH_LINK
Note that Slack allows you to "Star" rooms that you're interested in to pin them to the top of the room list on the left. This can be helpful given the large number of rooms in our workspace.
Finally, be aware that your discussions on Slack will be ephemeral: Old messages will become inaccessible as the conference goes on. Make sure to preserve any content you want to keep outside of Slack.