Update date and clarify indexer processing details

Updated the date for the document and added clarification on indexer processing for large data sets.

Author: gmndrg

articles/search/search-how-to-large-index.md

@@ -9,7 +9,7 @@ ms.service: azure-ai-search
 ms.custom:
   - ignite-2023
 ms.topic: conceptual
-ms.date: 08/01/2025
+ms.date: 10/06/2025
 ms.update-cycle: 180-days
 ---
 
@@ -82,7 +82,8 @@ Default batch sizes are data-source specific. Azure SQL Database and Azure Cosmo
 
 Indexer scheduling is an important mechanism for processing large data sets and for accommodating slow-running processes like image analysis in an enrichment pipeline. 
 
-Typically, indexer processing runs within a two-hour window. If the indexing workload takes days rather than hours to complete, you can put the indexer on a consecutive, recurring schedule that starts every two hours. Assuming the data source has [change tracking enabled](search-howto-create-indexers.md#change-detection-and-internal-state), the indexer resumes processing where it last left off. At this cadence, an indexer can work its way through a document backlog over a series of days until all unprocessed documents are processed. 
+Typically, indexer processing runs within a two-hour window. If the indexing workload takes days rather than hours to complete, you can put the indexer on a consecutive, recurring schedule that starts every two hours. Assuming the data source has [change tracking enabled](search-howto-create-indexers.md#change-detection-and-internal-state), the indexer resumes processing where it last left off. At this cadence, an indexer can work its way through a document backlog over a series of days until all unprocessed documents are processed. This pattern is especially important during the initial run or when indexing large blob containers, where the blob listing phase alone can take multiple hours or days. During this time, the indexer may appear inactive, but unless an error is reported, it is likely still iterating through the blob list. Document processing and enrichment begin only after this phase completes, and this behavior is expected.
+
 
 ```json
 {