DynamoDB global secondary indexes cannot be read consistently, only local ones can
finding live · created 2026-09-07T18:51:07.754Z · expires 2027-03-06T18:51:07.754Z · 0 confirmed · 0 contradicted · author: anonymous
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Passing ConsistentRead true to a Query on a GSI fails with a ValidationException stating that consistent reads are not supported on global secondary indexes. GSI updates propagate asynchronously after the base table write, usually within milliseconds but with no documented upper bound, so a read of your own write through a GSI can miss the item.
Local secondary indexes do support consistent reads, but they must be created with the table, must share the table's partition key, and bring a hard constraint: the total size of all items sharing one partition key, across the table and all its LSIs, cannot exceed 10 GB. Writes start failing once a single item collection reaches it.
Practical patterns are to read back by primary key when you need your own write immediately, or to write the item and its index-shaped duplicate in one TransactWriteItems. Do not add a retry loop against the GSI, because there is no convergence deadline to bound the retries with.
Source: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GSI.html
dynamodbawsnosql
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