---
id: "bug-1903"
status: "fixed"
status_updated: "2026-10-02"
status_note: ""
component: "apiserver"
severity: "wrong-result"
timestamp: "2026-10-01T12:21:25Z"
last_seen: "2026-10-01T12:21:25Z"
occurrences: 1
files: ["src/frontend/apiserver/controllers/jobs.go", "src/frontend/apiserver/store/query.go"]
tags: ["apiserver", "query", "pagination", "code-review"]
related: []
fix_commits: ["efff6b65", "ffb3e098"]
---

# bug-1903: apiserver GetJobsInfo page_token does not advance: the next page repeats the first

## Description
**Observed:** found by the reviewer of task 7.3 (spec job-array-one-based-index) while comparing handler behaviour with HEAD in a unit-test harness: following the `page_token` returned by `GET /xce/v1/jobs` (`GetJobsInfo`) returns the same page again instead of the next one. Reproduced at HEAD (before task 7.3) with a plain filter `{submit_user:eq:all}` and a small `limit`, so it is not caused by the element-selection work.
**Expected:** passing the returned `page_token` yields the next page of rows, and the last page returns no token.
**Impact:** wrong result: clients that page through job listings (`xcecli jobs list` with paging, REST callers) see the first page repeatedly and never reach later jobs.
**Found by:** review (task 7.3 of spec job-array-one-based-index, 2026-10-01)

## Environment
- OS: no /etc/os-release; Docker container; NixOS kernel; kernel Linux 6.18.33 x86_64
- libc: n/a (pure-Go handler path); host glibc 2.40
- Toolchain: gcc (GCC) 15.2.0, meson 1.9.1, Go from the nix dev shell
- Build: asan (build.jai); exercised through the non-cgo Go unit-test build of src/frontend/apiserver (the defect is in pure Go)
- Code: scheduler-framework @ c30e5f1d (HEAD before task 7.3) and 3457d892
- Deployment: none (controllers handler test with an in-memory store); any apiserver with more jobs than the page limit

## Reproduction
1. In a controllers handler test (non-cgo, `jobs_handler_test.go` fixture), seed more jobs than the page limit.
2. `GET /xce/v1/jobs?filter={submit_user:eq:all}&limit=2`; read `page_token` from the response.
3. Repeat the request adding `&page_token=<token>`: the rows are the same as the first page.
- Frequency: deterministic (reviewer probe, 2026-10-01)
- Evidence: not kept (reviewer's temporary probe test, deleted)

## Root cause
`store/query.go` `findPageTokenIndex` decoded the token with `json.Unmarshal` into `interface{}`, so the token's `unique_job_id` became a float64. Array element IDs set bit 62, where float64 spacing is 1024, so the token no longer named the page's last row: with no exact match `findPageTokenIndex` returned 0 and every page restarted at row 0 -- the reported repeat-the-first-page (the review fixture's rows are array elements); with a near match it skipped rows instead. `queryControlRowsByJobID`, `FetchJobList` and `GetJobByIDs` page until the token is empty, so the restart case also looped forever on arrays over 1000 elements.

## Fix
efff6b65: `findPageTokenIndex` decodes with `json.Decoder.UseNumber()` and converts integers to int64 (floats stay float64), so 63-bit job IDs compare exactly. ffb3e098 adds the handler-level regression test.

## Verification
- Test: `TestJobHandler_QueryPagination` in `src/frontend/apiserver/controllers/jobs_handler_test.go` (GetJobsInfo, limit=3, follows `page_token`): RED with efff6b65's parent `store/query.go` (the same three rows returned on every page until the loop guard stopped it), GREEN after; `TestPaginateRowsArrayElementIDsRoundTripPageToken` in `store/query_test.go` (2500 array elements, limit 1000): RED before efff6b65 (2452 of 2500 rows), GREEN after
- Suites: apiserver store/utils/controllers go test ok (CGO_ENABLED=0)
- Live: n/a (unit/handler level: the REST handler runs against the real store in the fixture)

## References
- Related: bug-1898 (found while fixing it)