title: Firedac multiple pools of connections
body: <p>I'm in process of upgrading our client-server ERP app to multi-tier. We want to offer our customers the possibility having their databases in cloud(hosted in our server).So, clients are written in Delphi, server is a http IOCP server written also in Delphi (from mORMot framework), for dbs we use Firebird embedded.</p>
  
  <p>Our customers(let's say 200), can have 25-30 Firebird databases (total 5000-6000 databases), accessed by 4-5 user per each customer. This is not happening all at once. One user can work in one db, other 2 users can work in another db, but all the dbs should be available and online. So, I can have 800-1000 users working at 700-900 dbs. Databases are not big, typically 20-30 MB each but can go to 200 MB.</p>
  
  <p>This is not data sharding so please don't suggest to merge all databases together, I really need them individually with possibility to backup/restore/replace each one of them.</p>
  
  <p>So, I need multiple pools of connections - for every database I need a pool of let's say 2 connections. I read about Firedac connection pooling. It seems that TFDManager should be perfect for me. I define multiple "ConnectionDef"s with "Pooled=true" and it can maintain multiple pools of connections (each connection lasting until some minutes of inactivity).</p>
  
  <p>Questions:</p>
  
  <ol>
  <li><p>I have to create all "ConnectionDef"s before server starts serving requests?</p></li>
  <li><p>Can TFDManager "handle" requests (and time-out connections on inactivity), while in other thread I need to create a new database , so automatically I need to create a new pool of connections and start serving requests from newly created database. Practically can I call FDManager.AddConnectionDef(..) while other pools are in use?</p></li>
  </ol>