Using IN clause vs. multiple SELECTs

Question

I was wondering which of these would be faster (performance-wise) to query (on MySQL 5.x CentOS 5.x if this matters):

SELECT * FROM table_name WHERE id=1;
SELECT * FROM table_name WHERE id=2;
.
.
.
SELECT * FROM table_name WHERE id=50;

or...

SELECT * FROM table_name WHERE id IN (1,2,...,50);

I have around 50 ids to query for. I know usually DB connections are expensive, but I've seen the IN clause isn't so fast either [sometimes].

Answer 1

I'm pretty sure the second option gives you the best performance; one query, one result. You have to start looking for > 100 items before it may become an issue.

See also the accepted answer from here: MySQL "IN" operator performance on (large?) number of values

Answer 2

IMHO you should try it and measure response time: IN should give you better performances...
Anyway if your ids are sequential you could try

SELECT * FROM table_name WHERE id BETWEEN 1 AND 50