How macOS actually works
Every file search tool makes this choice, and it determines almost everything else about how it behaves.
Read the filesystem on every query. find does this, and so does Find Any File.
For: always correct, nothing to maintain, no background process, no memory held, works on any volume regardless of format.
Against: slow in proportion to the number of files. Seconds, not milliseconds. Which means you stop using it for casual questions, which is the real cost.
Read once, keep the answer, search that. Spotlight, locate and Everywhere all do this.
For: instant. Refinement is nearly free. Filters on size and date become possible across everything at once.
Against: the index can be stale, must be maintained, occupies disk, and needs a first scan.
An index rebuilt on a schedule is wrong between rebuilds — locate on macOS updates weekly, which is why it feels unreliable.
An index driven by filesystem change notifications is a different proposition. macOS reports every change through FSEvents, with a replayable position, so an index can be current within milliseconds of a file being saved and can catch up on everything that happened while it was closed.
That is the distinction worth asking about: not "does it use an index" but "how does it stay current".
Both are legitimate. The mistake is expecting an index to be exhaustive when it has an exclusion list, or expecting a live search to feel instant on six million files.
For the query, yes. It moves the cost to indexing time, which happens in the background.
Either by periodic rescanning or by subscribing to filesystem change events. The latter is why a good index reflects a file saved a second ago.
Everywhere keeps track of every file on your Mac — including the folders Spotlight hides and drives you have unplugged. Free for a day, then $19 once.
Download for Mac