Spotlight is supposed to find anything in seconds. In practice, a file you know is there doesn't show up. Or your Mac slows down, the fan spins up, and Activity Monitor shows mds_stores and mdworker_shared at the top.
I've been building Mac software for years, including a document search app of my own, so I deal with Spotlight constantly, both as a tool and as a benchmark. This article explains what happens in the background, how to find the actual culprit, and where Spotlight hits a limit that no index rebuild will fix.
Quick fix: five steps
- Check the status. Run
mdutil -s /in Terminal. If it says "Indexing disabled", indexing is off. - Wait after updates. After a macOS update, Spotlight rebuilds its index. Apple says this can take hours or even days. Keep the Mac plugged in and don't restart it.
- Check exclusions. System Settings → Spotlight → Search Privacy: is the folder or drive you're searching listed there?
- Check search categories. In Spotlight settings, "Documents", "Folders" and "PDF Documents" need to be enabled.
- Rebuild the index, but only if steps 1 to 4 didn't help. See below.
What Spotlight does in the background
Spotlight isn't one program but a chain of processes:
- mdworker / mdworker_shared open new and changed files and extract text and metadata, using a plugin (an "importer") for each file type.
- mds_stores writes the results to the index, which lives in a hidden
.Spotlight-V100folder on each volume and easily grows to several gigabytes. - mds answers search queries.
- mediaanalysisd recognises text in images (Live Text), much later and at its own priority.
- corespotlightd handles what apps like Mail and Notes report themselves.
Normally a new file is in the index within seconds. That works as long as not too much happens at once.
Memory figures are misleading
Many people get worried when Activity Monitor shows mds using several gigabytes. On my development Mac (32 GB RAM, macOS 26.6), top reported 3.4 GB for mds. What was actually resident in RAM: 62 MB. The figure includes compressed and swapped memory. The bigger chunk was mds_stores at about 530 MB, still far from "Spotlight is eating my RAM".
The more useful question is what Spotlight is indexing right now.
Why your Mac slows down, and how to find the culprit
On my Mac, new mdworker_shared processes kept appearing, most of them only a second or two old. Something was writing files constantly, and Spotlight read every one of them. You can find out what without admin rights. This command lists the folders in which Spotlight picked up changed files during the last hour:
mdfind 'kMDItemFSContentChangeDate >= $time.now(-3600)' \
| awk -F/ '{print $2"/"$3"/"$4"/"$5"/"$6"/"$7}' \
| sort | uniq -c | sort -nr | head -15My result: 60,733 files in one hour, 71 % of them from a single node_modules folder in a web project, plus Xcode build output. I would never search any of those files with Spotlight.
Typical culprits:
node_modules,DerivedData,build,bin/objand other build folders- virtual machines and disk images
- folders where apps keep writing logs or caches
- large copy jobs and Time Machine backups
- a file that keeps crashing the importer
Fix: add these folders under System Settings → Spotlight → Search Privacy with "+". Developers can exclude their whole projects folder; you search code in your IDE anyway. Spotlight drops those entries from the index, and the constant load goes away.
What macOS 27 improves, and what it doesn't
macOS 27 "Golden Gate" has been available since 14 September 2026. Spotlight got a lot of attention:
- A long-standing bug is fixed. Since Mojave, plain text files weren't indexed if they started with certain character sequences. The bug is still present in macOS 26 and, according to Howard Oakley (Eclectic Light Company), fixed in macOS 27.0.
- Search understands more. Spotlight answers natural-language questions and works with Siri and Apple Intelligence. Apple also promises that new content becomes searchable almost immediately.
What remains:
- After the update, macOS reindexes everything, on top of Photos library analysis and Apple Intelligence work. A day or two of noticeable load is normal.
- In everyday use, the basic principle hasn't changed: every changed file gets read again. Initial tests on macOS 27 show no significant improvement here. If you work with developer tools, virtual machines or large archives, you still need to maintain your exclusion list.
- Scanned documents remain a blind spot. More on that below.
Checking and rebuilding the index
A rebuild is not a cure-all. If indexing is already running, starting over only makes it take longer. Rebuild when the index is demonstrably damaged, meaning files are permanently missing although nothing is excluded.
Via System Settings (Apple's way): add the affected volume to Search Privacy, wait a few seconds, then remove it. Spotlight then rebuilds the index.
In Terminal:
| Command | Effect |
|---|---|
mdutil -s / |
show status |
sudo mdutil -E / |
erase and rebuild the index |
mdimport -L |
list installed importers |
Don't switch Spotlight off entirely
A common tip online is sudo mdutil -a -i off. It does make things quiet, but search in Apple Mail, Finder search and every app that relies on the Spotlight index stop working properly. Targeted exclusions solve the same problem without the side effects.
What Spotlight can't find at all: scanned PDFs
This is the limit no rebuild will fix. A PDF from a scanner is initially just a series of images. It only becomes searchable if text recognition (OCR) added an invisible text layer during scanning. Without that layer, Spotlight finds not a single word in it, however well the index is maintained. Howard Oakley has looked into this several times: Live Text recognises the text when you view it, but doesn't create a text layer, and macOS doesn't analyse images inside PDFs for search at all.
Initial tests on macOS 27 show no significant improvement here either.
Unfortunately, these are exactly the documents you need to find later: contracts, invoices, tax notices, letters, old paper files.
There are two ways around it:
- Add text recognition after the fact. Many scanning and PDF apps can create a text layer, and then Spotlight finds the text too. With a large archive that's a lot of manual work, and every new file has to go the same route.
- Use a search tool with its own OCR and its own index. These recognise the text themselves and don't depend on the Spotlight index. Many popular search tools are built on the Spotlight index and share the same blind spot. One tool with its own text recognition is PDF Content Search, which I develop.
How PDF Content Search handles it
PDF Content Search recognises text in scanned PDFs and images using Apple's text recognition, right on your Mac, with no upload. It keeps its own index, independent of Spotlight. You can even exclude a document archive from Spotlight and still search it.
- search for words and exact phrases, exclude individual terms
- matches are highlighted in the document, one keystroke jumps to the next
- watched folders stay up to date automatically
- Apple Mail including PDF and image attachments is searchable
- text recognition, index and search run locally on your Mac, no tracking
To be fair: the initial text recognition of a large archive takes processing time in PDF Content Search too. After that the app idles and only works when new documents arrive.
€89.99 one-time purchase, no subscription.
FAQ
Why can't Spotlight find my file even though it's there?
Usually indexing is still running (after an update), the folder is listed under Search Privacy, the category is disabled in settings, or it's a scanned PDF without a text layer.
What is mds_stores, and can I quit it?
mds_stores writes indexing results to the Spotlight index. Quitting it doesn't help, macOS restarts it immediately. Find out what's being indexed and exclude the folder if appropriate.
How long does indexing take after a macOS update?
Depending on the amount of data, a few hours to two days. Higher load during that time is normal.
Will disabling Spotlight make my Mac faster?
In the short term, yes, but Mail and Finder search suffer. Targeted exclusions under Search Privacy are the better solution.
Can Spotlight find text in scanned PDFs?
Only if the PDF has a text layer, meaning OCR ran during scanning. Without one, Spotlight finds nothing in it.
Does Spotlight find files on a NAS?
Only if the server itself provides Spotlight search. macOS doesn't index network volumes locally.
Sources
- Apple Support: Rebuild the Spotlight index on your Mac
- Eclectic Light Company: Are your text secrets safe in a PDF or image? (01/2024)
- Eclectic Light Company: How to search Spotlight for Live Text and objects in images (08/2025)
- Eclectic Light Company: When and how to rebuild Spotlight indexes (11/2024)
- Eclectic Light Company: In the background: Spotlight indexing (02/2026)
- Eclectic Light Company: Spotlight indexing bug fixed in Golden Gate (09/2026)
- Alfred: Excluding node_modules from Spotlight
Apple, Mac, macOS and Spotlight are trademarks of Apple Inc. This article is not affiliated with Apple.