Startup sequence repair scans all historical orders and bills #1182

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Summary and measured startup impact

initDatabase() calls repairSequences() unconditionally after migrations and the startup integrity checks. On each call, the repair reads every non-NULL order_number and bill_number into JavaScript, parses the values, then checks/updates sequence state by date. This includes a normal desktop launch, not just a migration or recovery.

The synthetic 10-year workload below (365,000 orders and 365,000 bills) measured a median repairSequences() time of 337 ms on the test host. initDatabase() took 2.07 s total, so the repair accounted for about 16% of database initialization. Each scan materialized about 28.6 MiB of live JS heap after a forced GC while keeping its result array live. Beyond the scans, the repair does a sequence-state lookup for each recognized date and number type (7,300 lookups at 3,650 dates). This is a measurable delay and memory cost for a plausible high-volume, long-lived store. Smaller 50k/100k histories cost 41/79 ms respectively. These are database-initialization results, not end-to-end Electron launch timings; the integrity check and other startup work also contribute to the totals.

Audited source, commit, and environment

• Repository branch: main
• Audited commit: 7ca68a0a14e8be8557d0038af4977f144251320a
• Test host: Node v26.9.0, macOS 25.6, arm64, 16 GiB RAM; better-sqlite3 / SQLite 3.53.4.
• Source was cloned to a dedicated /tmp checkout. All benchmark rows lived in disposable databases under /tmp; no production or user database was opened or changed.
• Startup path: main/index.ts calls initDatabase() during app initialization. main/db.ts runs migrations, integrity checks, then sequence repair and other repairs. (The audited SHA is 7ca68a0a14e8be8557d0038af4977f144251320a.)
• The scans and repair contract are in repairSequences. Orders and bills have unique, non-NULL number columns (orders, bills); sequence state has a composite (name, date) key (migration v10).
• getNextSequence() atomically increments the (name, date) high-water value (source).

Repair requirements and invariants

Migration v10 drops and recreates sequences to change its key to (name, date), discarding old sequence rows. The repair exists to rebuild counters from persisted orders/bills after that reset and to recover missing or stale counters without reusing an existing number.

Current behavior is:

• Recognize only ORD-<8 digits>-<digits> and INV-<8 digits>-<digits>.
• For each recognized date bucket, derive the greatest numeric suffix from history.
• Insert a missing counter or raise a counter that is below history; never lower a higher counter. Thus gaps do not cause reuse: the next value must exceed the maximum, not the row count.
• Ignore nonmatching/legacy/custom formats. In particular, this regex does not reconstruct counters for customized prefixes or monthly/financial-year/no-period bill formats. Any replacement should make this coverage boundary explicit rather than claiming all configured formats are recovered.

Dataset and benchmark methodology

The current schema was created by initDatabase() in the isolated checkout. Synthetic normal histories were inserted transactionally at 100 orders/day, one bill per order, with matching daily sequence rows and generated-format identifiers. Each size was then reopened repeatedly through the real initDatabase() path. Timings are medians over 4 warm reopens for sizes through 100k and 3 for 365k. The actual repairSequences() body was timed in-memory; no repository source was edited. Query time measures each exact .all() scan. Full init time includes migrations/checks/other startup repairs, not just sequence repair.

For heap measurement, a separate run forced GC before and after each scan while retaining the returned array. This estimates live JS heap for that array, not total process peak/RSS. Reopen runs were warm-cache measurements on this host.

Query plans and source references

EXPLAIN QUERY PLAN on the initialized schema returned:

SCAN orders USING COVERING INDEX sqlite_autoindex_orders_1
SCAN bills USING COVERING INDEX sqlite_autoindex_bills_1

So these are full scans of the unique-number covering indexes, not table-row scans. The .all() calls still transfer and instantiate every indexed number in JavaScript. The existing explicit indexes cover other order/bill fields, not these number columns; the unique constraints provide the covering indexes.

Pinned references: initDatabase() and unconditional call, repairSequences(), v10 sequence-table reset, and atomic sequence generation.

Recovery coverage and existing tests

The reason for processing history is valid: after v10 or another loss/staleness of sequence state, the persisted number is authoritative and a counter reset to 1 can collide with the unique order/bill number. The repair safely raises counters, but performs the same work again on every successful initialization even when state is already correct.

The existing tests/sequence-generation.test.ts verifies the composite key, default generation, 50 generated orders, and supported numbering settings; it does not exercise startup repair over historical rows or scale. tests/upgrade-path.test.ts covers old-schema migration and data preservation but not sequence recovery or large histories. No sequence-repair performance test or documented history-size limit was found. npm run test:sequence (22/22), npm run test:order-numbering-settings (18/18), and npm run test:upgrade-path passed on the audited checkout.

Behavior checks against disposable history passed: normal counters stayed correct; a 1,3 gap with stored counter 1 repaired to 3 and next generated 0004; missing state was seeded to 8; existing high-water 25 stayed 25; zero/non-numeric/mixed/overflow suffixes were ignored; nonmatching legacy/custom formats were not seeded.

Alternatives worth evaluating

• A plain MAX(order_number) or row count is not equivalent: counters are per date, suffixes are numeric (not lexical), gaps matter, and existing higher counters must not be lowered.
• A strict SQL aggregate grouped by parsed date and numeric suffix could preserve the current recognized-format semantics for normal in-range numbers while avoiding N JavaScript result objects. It would still traverse the covering index, and its matching/cast behavior must be tested against the current regex and numeric parsing.
• To avoid all-history work on ordinary boots, consider rebuilding only when sequence state is known to have been reset (migration/import/restore) or using a durable repair-needed/high-water marker. That must retain a reliable recovery trigger for every path that can replace or lose sequence state.

Acceptance criteria

• Preserve the no-reuse contract: counters are per (name, date), missing/lower state advances to the greatest persisted recognized suffix, higher state is never lowered, gaps do not reuse values, and next-number generation remains atomic.
• Preserve recovery after migration v10 and any supported restore/import path; add regression coverage for clean history, gaps, absent/lower/higher counters, malformed suffixes, and explicit behavior for legacy/configured numbering formats (including the current regex coverage boundary).
• Add repeatable startup-repair performance and heap coverage at 100k and at least 365k rows per table. Demonstrate that ordinary startup avoids materializing all historical identifiers into JS, or document measured bounds if a scan remains.
• Keep database initialization correctness and unique-number behavior intact on recovery; do not solve this by discarding history or resetting counters.

Duplicate check and reference

Searches across open and closed issues found no matching startup-performance report. Closed #29 is about replacing fixed substr extraction with regex, and merged #28 introduced the repair for the v10 reset; neither reports recurring scan cost.

Reference: ARCH-012b.