what's the most effecient way to query all the messages in a group chat application? - sql

Question

i will use an example to illustrate my question.
you have a group-chat table that stores data about group chat.
-------------------+
id | name |owner_id|
-------------------+
33 | code | 45
you have a messages table that hold messages
-------------------------------------+
id | content | user_id | chat_room_id
-------------------------------------+
5 | "hello" | 41 | 33
2 | "hi" | 43 | 33
you have a users table that holds user information and which group chat they are part of:
-------------------------------------+
id | name | chat_room_id
-------------------------------------+
5 |"nick"| 33
2 |"mike"| 33
is this the right way to set up the database?
without joints or foreign keys. what's the most efficient way to load all the messages and user data and have it in a form that allows you to construct a ui where the user data is displayed next to the message?
My solutions:
if you query the messages database and retrieved all the messages where chat room id is equal to 33, you're gonna get an array that looks like
[
{
id : 5,
user_id : 41,
content : "hello"
},
{
id : 2,
user_id : 43,
content : "hi"
}
]
as you can see the user ids are part of the message object.
solution 1 : (naive) :
loop through the messages array and query the database using the user id.
this is a bad solution since querying the database from a loop is never a good idea.
solution 2 : (efficient but less data to send in the response) :
loop through the messages array and construct an array of user ids and use that in a query
using WHERE user_id IN
then loop through the array of users and construct a hash table using the user id as a key since it is unique.
on the front end just loop through the messages array and lookup the user.
is this solution going to be very slow if you have a large amount of messages. will it scale well since it's O(n).
solution 3 : (efficient but more data to send in the response) :
its the same as before but the difference here is adding properties to the messages object that store user data.
the problem with this solution is that you will have duplicate data since one user can publish multiple messages.
these are my solutions i hope to hear yours.
for context : system design videos on youtube don't address this part of chat apps. if you found one that does please post the link.