Which is better - one query with two JOINs or three queries?

Question

PHP

When programming in PHP, the question arose: is it better to make a more complete query to get all the data from three tables at once, or to make three different queries?
In the first request by date, information containing two identifiers is selected, for which detailed data corresponding to these identifiers is pulled out.
That is, in one request, information can be duplicated in the returned data (in different lines, part of the data corresponding to the identifier can be repeated).
The query is unlikely to return more than a hundred rows, most likely up to twenty. Is there a noticeable performance difference when making three queries?
Simplified structure:

t1 [ time, t2_id, t3_id ]
t2 [ t2_id, t2_info ]
t3 [ t3_id, t3_info ]

Answer 1

If the tables are conditionally large (> 1,000,000), and little data is expected in the query results ( < 1,000 ), it will be noticeably faster to make 3 queries of the form where id in (1,2,3)explicitly listing the necessary id in the queries

Answer 2

It can be different, it is necessary to measure in each specific case separately.

Answer 3

With a small number of rows, JOIN is better. There is another question here - if you create a connection to the database after each request and then disconnect - there will be just ballast operations that can be avoided like 2 fingers.

Answer 4

In general, one is better. You need to start with it. When it starts to slow down, then only then start profiling, look at query plans and start optimizing. Premature optimization is evil.