Compression problem?
 

So i replaced my battery after my old one wouldnt hold a charge
and it started right away. Next start it took a little longer and a little longer.
Brought it into canadian tire cause it was the only shop open at the time cause
of my work hours.
Anyways they diagnosed it with a compression problem so there changing
my spark plugs.
Im sorry I didnt do a better search on the problem but will this fix it?
They're gonna call me back in 8 hours but honestly cant sleep.
This car has costed me too much besides this problem and am probably
gonna sell this car for parts or something if it doesnt work.

If it's low compression, a new set of spark plugs would not help

Unless there is a guy @ the Canadian Tire that you took the car to knows how to work on Rotary Engines. I wouldn't trust him/her.

J is right on...unless the mechanic has Mazda Rotary Engine experience, he knows little what he is talking about, and PLEASE be careful, make sure he installs the correct RE Spark Plugs for the RX-8.

9.999 times out of 10, IF your RX-8 has 'REAL' low compressions then you are in the need of a new (reman) engine.

I have not looked back at your other posts, but, you could also have poor Ignition Coils/Leads...or Starter Motor.

Why does he think it is a compression issue and what tool did he use to diagnose this?

What miles has it done, years, trans.??

You may also want to make sure he's aware of leading and trailing plugs. You don't want them put in backwards...

And like mentioned above, it's just as likely the coils are going, not just the plugs. They should be inspected.

If the car starts running reliably after replacement of coils/plugs, you should invest in a compression test. If it is not too far below minimum you can try a seafoam treatment to see if it puts you back in the good range.

Otherwise, a replacement is definitely in order.