comments clarified

docker/README.md

@@ -9,7 +9,7 @@ All images are available at https://hub.docker.com/r/tinode/
 	$ docker network create tinode-net
 	```
 
-3. Decide which database backend you want to use: RethinkDB, MySQL or MongoDB. Run the selected database container, attaching it to `tinode-net` network:
+3. Decide which database backend you want to use: MySQL, PostgreSQL, MongoDB or RethinkDB. Run the selected database container, attaching it to `tinode-net` network:
 
 	1. **MySQL**: If you've decided to use MySQL backend, run the official MySQL Docker container:
 	```

server/auth/code/auth_code.go

@@ -195,7 +195,7 @@ func (authenticator) GetResetParams(uid types.Uid) (map[string]interface{}, erro
 	return nil, nil
 }
 
-// Replace all occurences of % with / to ensure SQL LIKE query works correctly.
+// Replace all occurrences of '%' with '/' to ensure SQL LIKE query works correctly.
 func sanitizeKey(key string) string {
 	return strings.ReplaceAll(key, "%", "/")
 }

server/db/rethinkdb/adapter.go

@@ -2734,8 +2734,9 @@ func (a *adapter) FileDeleteUnused(olderThan time.Time, limit int) ([]string, er
 	return locations, err
 }
 
-// Given a select query against 'messages' table, decrement corresponding use counter in 'fileuploads' table.
-func (a *adapter) decFileUseCounter(msgQuery rdb.Term) error {
+// Given a select query, decrement corresponding use counter in 'fileuploads' table.
+// The 'query' must return an array, i.e. GetAll, not Get.
+func (a *adapter) decFileUseCounter(query rdb.Term) error {
 	/*
 		r.db("test").table("one")
 			.getAll(
@@ -2753,7 +2754,7 @@ func (a *adapter) decFileUseCounter(msgQuery rdb.Term) error {
 	*/
 	_, err := rdb.DB(a.dbName).Table("fileuploads").GetAll(
 		rdb.Args(
-			msgQuery.
+			query.
 				// Fetch messages with attachments only
 				Filter(rdb.Row.HasFields("Attachments")).
 				// Flatten arrays

server/tinode.conf

@@ -304,8 +304,8 @@
 			// MongoDB configuration.
 			"mongodb": {
 				// Connection string https://www.mongodb.com/docs/manual/reference/connection-string/
-				// Options configured with the connection string override any other options
-				// (only 'uri' is used to the server, all other options ignored).
+				// Options configured with the 'uri' connection string override all other options
+				// (only 'uri' is sent to the server, all other options are ignored).
 				// If you are using Atlas, then you MUST use 'uri' to connect. See here:
 				// https://www.mongodb.com/docs/manual/reference/connection-string/#std-label-connections-dns-seedlist
 				// Something like