# How the search index works — and how to rebuild it

One index per catalog, kept current by the Catalog Service — what's in it, the four failure patterns and which one actually calls for a rebuild, and the Catalog Manager rebuild that runs in the background while search stays up.

Product: content-central · Versions: 7.x · Audience: system-administrator · Time: 15 minute read · Last verified: 2026-09-05

Canonical: https://help.ademero.com/content-central/search-and-find/how-the-search-index-works

**By the end of this page you'll know what the index holds and who keeps it current — and, before you reach for the rebuild, which of the four index failure patterns you're actually looking at, because a rebuild fixes exactly one of them.**

## The shape of it

- **One index per catalog**, stored under the index root (Configuration Manager > **System Folders** > **Index root folder:**). A catalog's searchability is its index's health — one catalog searching badly while others are fine points at *its* index.
- **What's indexed:** each document's full text *and* its field values, names, and dates — which is why both content search and field search answer from the same machinery.
- **Who keeps it current:** the **Ademero Content Central Catalog Service** on the server. New and changed documents queue for indexing and the service works the queue continuously — plus each catalog's own update schedule if one is set. No service, no fresh index.

## Four failure patterns, one of which wants a rebuild

| Pattern | What's really wrong | The fix |
| --- | --- | --- |
| **Recent documents missing** from results, older ones fine | The Catalog Service is stopped or backlogged — documents are *waiting*, not lost | Start the service; the backlog drains. A rebuild does nothing while the service is down |
| **A document's text you can see isn't searchable** | The document has no text layer — an OCR gap, not an index gap | [The searchability article](/content-central/search-and-find/why-text-you-can-see-isnt-searchable), and the [Make Searchable backfill](/content-central/search-and-find/make-already-captured-documents-text-searchable) at scale |
| **A whole catalog returns nothing**, silently | The index path is unreachable — moved disk, permissions | Fix the path/permissions (System Health flags this) |
| **Search-engine errors in the event log**, documents erratically findable | The index itself has bad entries — and failed documents are **not** retried automatically | **This is the rebuild.** |

## Rebuilding

1. In **Catalog Manager** (on the server), select the catalog, choose **Rebuild selected catalog's index** in the action drop-down at the bottom, and click **Go** (**Rebuild all catalogs' indexes** for the sweep).

2. Read the confirmation as a schedule note, not a threat: "During an index rebuild, documents will become available as they are reindexed. Also, an index rebuild may take a long time if there are many documents in the catalog." Search stays up throughout — results are simply incomplete until the rebuild finishes.

3. The dialog then says the part people miss: "The catalog should update shortly. **Check the Windows Event Log for completion status.**" The rebuild is queued for the Catalog Service and runs in the background — the dialog closing means *started*, and the Event Log is where *finished* shows.

A rebuild re-flags every document and reindexes from stored text — it doesn't re-OCR anything, which is why it can't fix the missing-text pattern above.

> **NOTE:** Catalog Manager's **Details...** for a catalog shows the index's vitals — Updated, Documents, Words, Size, Fragmentation — worth a glance before and after: "Updated: Never" or a document count far below reality tells its own story.

**Success check:** after the Event Log reports the update complete, search for a phrase from a recently added document and from an old one — both hitting means the index covers its whole span again.

## What's next

- [Why text you can see isn't searchable](https://help.ademero.com/content-central/search-and-find/why-text-you-can-see-isnt-searchable)
- [Make already-captured documents text-searchable](https://help.ademero.com/content-central/search-and-find/make-already-captured-documents-text-searchable)