[LeeroyHannigan]

Part of #489 (row O3).

Select=ALL_PROJECTED_ATTRIBUTES without an IndexName now answers with the 1 validation error detected: prefix DynamoDB uses, on Query and on Scan.

What the service answers

Measured on 2026-10-25 at 21:13 and 21:53 UTC in us-east-1, each request sent twice with the same answer:

Request	Answer
Query, KeyConditionExpression, no ConsistentRead	1 validation error detected: ALL_PROJECTED_ATTRIBUTES can be used only when Querying using an IndexName
Query, KeyConditionExpression, ConsistentRead false	same
Query, KeyConditionExpression, ConsistentRead true	same
Query, legacy KeyConditions	same
Scan	same

Main sends the sentence without the prefix on all five.

The change

Query and Scan share the refusal in validate_select_projection (crates/core/src/validation/mod.rs), so the text changes there. handle_scan holds a second copy of the sentence after the index lookup. The shared check always answers first for these requests, so that copy is not reached today; it gets the same text so a later reorder of the Scan checks cannot bring the old one back.

Tests

tests/test_select_all_projected_attributes.py: 4 dual-target wire tests, one per measured Query form and one for Scan, asserting the full message.

Run locally on 2026-10-25 against SQLite release builds:

• at the first commit: the new file 4 passed; on main 4 failed, each on the missing prefix alone;
• tests/test_query_scan.py (116) and tests/test_wording_parity_validation.py (7) pass at the head and on main; they assert the sentence as a substring;
• at the head, with the second copy changed: the new file, tests/test_query_scan.py, tests/test_wording_parity_validation.py and every test whose name contains test_scan, 158 passed;
• cargo +1.97.0 fmt --all -- --check, cargo +1.97.0 clippy -p extenddb-engine -p extenddb-core --all-targets -- -D warnings, and cargo test -p extenddb-engine -p extenddb-core (698 passed).

CI runs the new file in run-integration, run-integration-sqlite, mongodb-pytest and cassandra-pytest.

Not changed here

Measured in the same runs, on main and unchanged by this PR:

• Query with ALL_PROJECTED_ATTRIBUTES on a table that does not exist: the service answers the sentence above, ExtendDB answers ResourceNotFoundException, because it resolves the table first.
• Query with ALL_PROJECTED_ATTRIBUTES and AttributesToGet: the service answers 1 validation error detected: Cannot specify the AttributesToGet when choosing to get ALL_PROJECTED_ATTRIBUTES; ExtendDB answers the IndexName sentence.
• A FilterExpression syntax fault next to ALL_PROJECTED_ATTRIBUTES: both report the filter first, with different wording (Syntax error; token: "=", near: "=" on the service).
• Scan with ALL_PROJECTED_ATTRIBUTES and a ProjectionExpression: the service prefixes Cannot specify the ProjectionExpression when choosing to get ALL_PROJECTED_ATTRIBUTES; ExtendDB leaves it bare on Scan, and the code comment beside it says the service does. ALL_ATTRIBUTES and COUNT with a ProjectionExpression on Scan were not measured.

Merging

git merge-tree --write-tree adds no conflict against any of the 13 open PRs that change crates/core/src/validation/mod.rs, nor #562, which changes it through its base. #416, #395 and #200 conflict with main in the same files with or without this commit. #481 and #479 assert this sentence with endswith, so their tests pass after this lands; their comments saying ExtendDB omits the prefix become stale.