[analeis]

Replaces the PostgreSQL backend with SQLite, measured against the database server it replaces.

Both sides were benchmarked with the internal/db package taken from the respective commit, driven by the same harness over the same public API, on the same 8-core host. PostgreSQL 18.3 ran locally over a unix socket, so it was not charged for network latency. Figures are the median of three runs against a freshly created database, after a warm-up run excluded the cold-start checkpoint storm.

Query latency

Query latency, p50 (lower is better)

  GetGuild, p50                PostgreSQL █████████████████        60 µs
                               SQLite     ████        15 µs

  GetUser, p50                 PostgreSQL ██████████████████████████        89 µs
                               SQLite     ██████        22 µs

  GetModerationLogs page, p50  PostgreSQL ████████████████████████████████       110 µs
                               SQLite     █████████████        46 µs

  UpsertGuild, p50             PostgreSQL ██████████████████████████████████       118 µs
                               SQLite     █████████        30 µs

  LogModeration insert, p50    PostgreSQL █████████████████████        72 µs
                               SQLite     ████████        29 µs

  Median of three runs, 8-core host, 5k users and 50k moderation logs.

Operation	PostgreSQL	SQLite
GetGuild, mean	75 µs	15 µs	5.00x
GetGuild, p50	60 µs	15 µs	4.00x
GetUser, mean	92 µs	23 µs	4.00x
GetUser, p50	89 µs	22 µs	4.05x
GetModerationLogs page, mean	112 µs	48 µs	2.33x
GetModerationLogs page, p50	110 µs	46 µs	2.39x
UpsertGuild, mean	114 µs	34 µs	3.35x
UpsertGuild, p50	118 µs	30 µs	3.93x
LogModeration insert, mean	79 µs	32 µs	2.47x
LogModeration insert, p50	72 µs	29 µs	2.48x

Startup and bulk load

Startup and bulk load (lower is better)

  Startup (open + migrate)  PostgreSQL █         8 ms
                            SQLite     █         1 ms

  Seed 5k users + 50k logs  PostgreSQL ██████████████████████████████████     4,609 ms
                            SQLite     ████████████████     2,109 ms

  Median of three runs against a freshly created database.

	PostgreSQL	SQLite
Startup, open and migrate	8 ms	1 ms	8.00x
Seed 5k users and 50k moderation logs	4,609 ms	2,109 ms	2.19x

Concurrent load

Concurrent mixed load (higher is better)

  Concurrent mixed (8 goroutines)  PostgreSQL ███████████████ 13,640 ops/s
                                   SQLite     ██████████████████████████████████ 31,309 ops/s

  One third reads, two thirds writes. No errors in either engine.

	PostgreSQL	SQLite
Throughput	13,640 ops/s	31,309 ops/s	2.30x
Errors	0	0

SQLite serialises writes, so this is one writer against seven readers. The write-ahead log and a busy timeout keep the readers off the writer's path, and the pool is small on purpose.

Footprint

Data on disk (lower is better)

  Data on disk  PostgreSQL ██████████████████████████████████     91.1 MiB
                SQLite     ████      9.5 MiB

  After the same 5k users and 50k moderation logs were written.

	PostgreSQL	SQLite
Data on disk	91.1 MiB	9.5 MiB	9.59x
Server process	~31 MiB resident, separate container	none
Containers per instance	2	1
Images to pull	app + postgres:16-alpine (297 MiB)	app only (3 MiB)
Credentials	DB_USER, DB_PASSWORD, POSTGRES_PASSWORD	none
Healthcheck	required	none
Bot binary	11.0 MiB	14.1 MiB	+3.1 MiB

The binary grows because the SQLite engine is a pure Go port rather than a C library, which is what keeps the build at CGO_ENABLED=0 and the runtime image unchanged.

AI Usage disclosure

OpenCode with MiniMax M3.1 was used to migrate the backend, write the tests and the documentation, and produce the benchmarks above. The driver choice was settled by measuring the three candidates against the placeholder binding this codebase relies on: mattn/go-sqlite3 and ncruces/go-sqlite3 both bind $1-style placeholders by order of appearance rather than by index, which would have put the wrong values in the wrong place in the queries that build their argument list.

The implementation was reviewed or redirected atleast three times after the initial prompt for a thorough evaluation and feasibility of the migration.

sqlc was also evaluated and rejected due to being otherwise feasible but still in beta for SQLite, especially $ values.

Tested with go test ./..., custom-gcl including NilAway, and the Sphinx -W build, plus the container image built and run against a named volume.

[Vuks69]

no concerns from me