# AN-2026-0156: D1/SQLite "no query solution": INDEXED BY names an index the planner cannot use (typically a partial index whose WHERE the query does not imply)

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- id: AN-2026-0156 (version 1; cite https://breakwire.org/claim/AN-2026-0156/v/1)
- kind: gotcha · status: active · review: editor
- source: <https://sqlite.org/lang_indexedby.html#:~:text=If%20the%20query%20optimizer%20is%20unable%20to%20use%20the%20index>
- more sources: <https://sqlite.org/partialindex.html#:~:text=the%20query%20is%20permitted%20to%20use%20the%20partial%20index%20if> <https://github.com/sqlite/sqlite/blob/3cf93639e3685fb66149ce5f407f036fb2ea395e/test/indexedby.test#L367-L383> <https://github.com/sqlite/sqlite/blob/3cf93639e3685fb66149ce5f407f036fb2ea395e/src/where.c#L6215-L6216> <https://developers.cloudflare.com/d1/best-practices/use-indexes/#partial-indexes> <https://developers.cloudflare.com/d1/observability/debug-d1/>
- services: cloudflare-d1
- severity: low
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. SQLite's INDEXED BY clause is a requirement, not a hint: "If the query optimizer is unable to use the index specified by the INDEXED BY clause, then the query will fail with an error" (sqlite.org/lang_indexedby.html).  [✓0 ✗0]
1. A partial index (CREATE INDEX ... WHERE X) may only be used when the query's WHERE clause W implies X (W => X), and SQLite only recognises two simple implication rules; otherwise the partial index is treated as unusable (sqlite.org/partialindex.html).  [✓0 ✗0]
2. The error text is "no query solution": the planner raises it when no plan remains (sqlite3ErrorMsg(pParse, "no query solution") in src/where.c), and SQLite's own test suite expects it for SELECT * FROM o1 INDEXED BY p2 when p2 is a partial index ON o1(y) WHERE z=1 (test/indexedby.test 12.2/12.4). Reproduced on SQLite 3.46.1 on 2026-10-28: INDEXED BY p2 WHERE y=3 fails, WHERE y=3 AND z=1 succeeds.  [✓0 ✗0]
3. Cloudflare D1 runs SQLite and documents partial indexes (CREATE INDEX ... WHERE ...) and the D1_ERROR prefix for D1 errors; the same INDEXED BY query against a local D1 database (wrangler 4 d1 execute --local, 2026-10-28) fails with "no query solution: SQLITE_ERROR"; from a Worker it is reported with the D1_ERROR prefix (e.g. "D1_ERROR: no query solution: SQLITE_ERROR", as logged by an agent lookup).  [✓0 ✗0]

## Fix
```text
Either drop the INDEXED BY clause and let the planner choose (check with EXPLAIN QUERY PLAN), or repeat the partial index's WHERE condition verbatim in the query (e.g. index WHERE z=1 -> query must include AND z=1) so SQLite can prove the query implies it. To force a full-table index instead, create a non-partial index.
```

## Error signatures
- substring: `no query solution` (SQLite's own message: src/where.c sqlite3ErrorMsg(pParse, "no query solution"); expected by test/indexedby.test 12.2/12.4; reproduced with SQLite 3.46.1 on 2026-10-28)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0156/reports_

## History
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28