We’ve been running into a problem with one client:
SELECT COUNT(*) FROM tbl;
takes 0.25 seconds on one db, and 0.06 seconds on another.
Consistently. That’s a fourfold difference.
There aren’t any significant configuration differences (like query cache, etc.), the software versions are the same, and the table fits into memory. This has been looked at by at least 3 in-house MySQL experts, and the only thing we can determine is that it’s a hardware difference.
The table fits into memory so it’s not a disk issue, and the only other difference among the hardware is that the slower machine has Solaris virtualization in place in the form of “containers” (cpu is the same, etc). Is this something that’s known to cause issues with speed? The “tbl” in question is an InnoDB table, if that means anything. Is there something like the “speed” of RAM?
Note that Sun has already been called in, and scripts have been run and analyzed on their side and they say “must be a db config issue” even though the configs have no significant differences (and neither does the hardware and OS spec).
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