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AWS amazondynamodb: Clarify vector index backfilling behavior and status checks

Service: amazondynamodb · 2026-08-19 · Documentation low

File: amazondynamodb/latest/developerguide/VectorSearchDataSync.md

Summary

Updated explanation of index status transitions during backfilling and added operational guidance.

Security assessment

Enhanced operational documentation about index creation process without security implications.

Evidence

-When you add a vector index to a table that already contains items, DynamoDB backfills the index with the existing data. The index first transitions to `IndexStatus` `CREATING` while DynamoDB sets up the index infrastructure. It then moves to `IndexStatus` `ACTIVE` with `Backfilling` set to `true` while DynamoDB populates the index from existing base table data. New writes to the base table are replicated to the index during this phase, but `SearchVectors` returns an error until backfilling finishes. Use `DescribeTable` and wait until `IndexStatus` is `ACTIVE` and `Backfilling` is `false` before you search. See [Adding a vector index to an existing table](./VectorSearchWorkingWith.html#VectorSearchWorkingWith.Create.ExistingTable).

Diff

diff --git a/amazondynamodb/latest/developerguide/VectorSearchDataSync.md b/amazondynamodb/latest/developerguide/VectorSearchDataSync.md
index ac8a792d4..cf073b781 100644
--- a//amazondynamodb/latest/developerguide/VectorSearchDataSync.md
+++ b//amazondynamodb/latest/developerguide/VectorSearchDataSync.md
@@ -15 +15,5 @@ DynamoDB keeps a vector index synchronized with its base table automatically. Un
-When you add a vector index to a table that already contains items, DynamoDB backfills the index with the existing data. The index first transitions to `IndexStatus` `CREATING` while DynamoDB sets up the index infrastructure. It then moves to `IndexStatus` `ACTIVE` with `Backfilling` set to `true` while DynamoDB populates the index from existing base table data. New writes to the base table are replicated to the index during this phase, but `SearchVectors` returns an error until backfilling finishes. Use `DescribeTable` and wait until `IndexStatus` is `ACTIVE` and `Backfilling` is `false` before you search. See [Adding a vector index to an existing table](./VectorSearchWorkingWith.html#VectorSearchWorkingWith.Create.ExistingTable).
+When you add a vector index to a table that already contains items, DynamoDB backfills the index with the existing data. The index first transitions to `IndexStatus` `CREATING` while DynamoDB provisions the index infrastructure. It remains `CREATING` while DynamoDB populates the index from existing base table data, and reports `Backfilling` as `true` during that phase. New writes to the base table are replicated to the index while it backfills, but `SearchVectors` returns a `ValidationException` until backfilling finishes. When the index is ready, `IndexStatus` becomes `ACTIVE` and the `Backfilling` field is no longer reported. Use `DescribeTable` and wait until `IndexStatus` is `ACTIVE` and `Backfilling` is not `true` before you search.
+
+Index construction drives backfill duration, not the number of items in the base table. Even a table with very few items can take a substantial amount of time to finish backfilling. Poll `DescribeTable` rather than assuming a small table will be ready quickly.
+
+See [Adding a vector index to an existing table](./VectorSearchWorkingWith.html#VectorSearchWorkingWith.Create.ExistingTable).