db-noop

A no-op database server: PostgreSQL and MySQL/MariaDB wire protocols, answering every statement with a valid, empty response. It exists so that a benchmark client can be measured against a server that does no work. Against a real database, two clients make the server do the same work and the comparison measures the server; against db-noop it measures them.

Quickstart

cargo build --release
./target/release/dbnoop --port 5432 --mysql-port 3306 --workers 16

psql  -h 127.0.0.1 -p 5432 -U any_user
mysql -h 127.0.0.1 -P 3306 -u any_user

The PostgreSQL listener is on by default; the MySQL listener only when --mysql-port is given. --profile tpcc turns on the numbers a TPC-C client reads its throughput from - off by default.

docker run --network host --security-opt seccomp=unconfined \
  ghcr.io/stroppy-io/db-noop:0.3.0 --port 5432 --mysql-port 3306 --profile tpcc

io_uring needs the seccomp profile opened; without it the server says so and serves the same codec over epoll. --network host keeps the kernel's SO_REUSEPORT balancing in the loop, with no proxy in the measurement.

Which clients it measures

Client	Runs	Needs
HammerDB, PostgreSQL TPROC-C (function mode)	yes	--profile tpcc
HammerDB, MySQL TPROC-C (stored procedures)	yes	--profile tpcc
stroppy-rust, both protocols	yes	--no-verify --profile tpcc
stroppy-go	no - it validates the rows it reads, and there are none
HammerDB, MySQL client-side SQL arm	no - it needs point lookups, and there is no data

An unsupported client gets no number, not a low one. Every db-noop figure is published next to a real-server run: it says how much of a client's cost the database was not, and it is not a TPC-C result.

What it answers

A SELECT answers its columns and no rows; INSERT/UPDATE/DELETE answer INSERT 0 0/UPDATE 0/DELETE 0; a constant select (select 1, select @@version) answers one row of exactly those values. A failure a benchmark injects (SIGNAL, RAISE, an unknown CALL) is answered as the error it is, so the client's rollback path runs and counts nothing; a NULL written into a NOT NULL column is one too, under --profile tpcc only, where writing one is the injection rather than the data.

--profile tpcc adds the numbers a TPC-C client reads: the district sum, the population counts, pg_stat_database's transaction totals and show global status's commit counters, all derived from --warehouses. The counters run whether the profile does or not, and the stats line says synthetic NOPM when it is on.

Where to read more

• docs/protocols.md - every command and statement, and what it is answered with, on both protocols.
• docs/measurements.md - throughput, the io_uring ring, and how to reproduce it with saturate.
• DESIGN.md - why these answers, and the rules behind them.
• docs/review/2026-10-28-design-panel.md
  • the design review, verbatim.
• TODO.md - the hot path and the logging, with their costs.

Configuration and build

--help lists every flag; DBNOOP_* (or the older PGNOOP_*) sets each from the environment, and dbnoop.json (or pgnoop.json) from a file. dbnoop and pgnoop are the same program under two names. scripts/release-local.sh builds the static musl artifacts and their checksums; dist builds them in CI.