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Show HN: SQL-tap – Real-time SQL traffic viewer for PostgreSQL and MySQL

Real-time SQL traffic viewer — proxy daemon + TUI client.

sql-tap sits between your application and your database (PostgreSQL or MySQL), capturing every query and displaying it in an interactive terminal UI. Inspect queries, view transactions, and run EXPLAIN — all without changing your application code.

demo

brew install --cask mickamy/tap/sql-tap
go install github.com/mickamy/sql-tap@latest
go install github.com/mickamy/sql-tap/cmd/sql-tapd@latest
git clone https://github.com/mickamy/sql-tap.git
cd sql-tap
make install

PostgreSQL

FROM postgres:18-alpine
ARG SQL_TAP_VERSION=0.0.1
ARG TARGETARCH
ADD https://github.com/mickamy/sql-tap/releases/download/v${SQL_TAP_VERSION}/sql-tap_${SQL_TAP_VERSION}_linux_${TARGETARCH}.tar.gz /tmp/sql-tap.tar.gz
RUN tar -xzf /tmp/sql-tap.tar.gz -C /usr/local/bin sql-tapd && rm /tmp/sql-tap.tar.gz
ENTRYPOINT ["sql-tapd", "--driver=postgres", "--listen=:5433", "--upstream=localhost:5432", "--grpc=:9091"]

MySQL

FROM mysql:8
ARG SQL_TAP_VERSION=0.0.1
ARG TARGETARCH
ADD https://github.com/mickamy/sql-tap/releases/download/v${SQL_TAP_VERSION}/sql-tap_${SQL_TAP_VERSION}_linux_${TARGETARCH}.tar.gz /tmp/sql-tap.tar.gz
RUN tar -xzf /tmp/sql-tap.tar.gz -C /usr/local/bin sql-tapd && rm /tmp/sql-tap.tar.gz
ENTRYPOINT ["sql-tapd", "--driver=mysql", "--listen=:3307", "--upstream=localhost:3306", "--grpc=:9091"]

1. Start the proxy daemon

# PostgreSQL: proxy listens on :5433, forwards to PostgreSQL on :5432
DATABASE_URL="postgres://user:pass@localhost:5432/db?sslmode=disable" \
  sql-tapd --driver=postgres --listen=:5433 --upstream=localhost:5432

# MySQL: proxy listens on :3307, forwards to MySQL on :3306
DATABASE_URL="user:pass@tcp(localhost:3306)/db" \
  sql-tapd --driver=mysql --listen=:3307 --upstream=localhost:3306

2. Point your application at the proxy

Connect your app to the proxy port instead of the database port. No code changes needed — sql-tapd speaks the native wire protocol.

3. Launch the TUI

All queries flowing through the proxy appear in real-time.

sql-tapd — SQL proxy daemon for sql-tap

Usage:
  sql-tapd [flags]

Flags:
  -driver    database driver: postgres, mysql (required)
  -listen    client listen address (required)
  -upstream  upstream database address (required)
  -grpc      gRPC server address for TUI (default: ":9091")
  -dsn-env   env var holding DSN for EXPLAIN (default: "DATABASE_URL")
  -version   show version and exit

Set DATABASE_URL (or the env var specified by -dsn-env) to enable EXPLAIN support. Without it, the proxy still captures queries but EXPLAIN is disabled.

sql-tap — Watch SQL traffic in real-time

Usage:
  sql-tap [flags] <addr>

Flags:
  -version  Show version and exit

<addr> is the gRPC address of sql-tapd (e.g. localhost:9091).

Key Action
j / ↓ Move down
k / ↑ Move up
Ctrl+d / PgDn Half-page down
Ctrl+u / PgUp Half-page up
/ Incremental search
s Toggle sort (chronological/duration)
Enter Inspect query / transaction
Space Toggle transaction expand / collapse
Esc Clear search filter
x EXPLAIN
X EXPLAIN ANALYZE
e Edit query, then EXPLAIN
E Edit query, then EXPLAIN ANALYZE
a Analytics view
c Copy query
C Copy query with bound args
q Quit
Key Action
j / ↓ Scroll down
k / ↑ Scroll up
x EXPLAIN
X EXPLAIN ANALYZE
e / E Edit and EXPLAIN / ANALYZE
c Copy query
C Copy query with bound args
q Back to list
Key Action
j / ↓ Move down
k / ↑ Move up
Ctrl+d Half-page down
Ctrl+u Half-page up
h / ← Scroll left
l / → Scroll right
s Cycle sort (total/count/avg)
c Copy query
q Back to list
Key Action
j / ↓ Scroll down
k / ↑ Scroll up
h / ← Scroll left
l / → Scroll right
c Copy explain plan
e / E Edit and re-explain / re-analyze
q Back to list 
┌─────────────┐      ┌───────────────────────┐      ┌────────────────────┐
│ Application │─────▶│  sql-tapd (proxy)     │─────▶│ PostgreSQL / MySQL │
└─────────────┘      │                       │      └────────────────────┘
                     │  captures queries     │
                     │  via wire protocol    │
                     └───────────┬───────────┘
                                 │ gRPC stream
                     ┌───────────▼───────────┐
                     │  sql-tap (TUI)        │
                     └───────────────────────┘

sql-tapd parses the database wire protocol (PostgreSQL or MySQL) to intercept queries transparently. It tracks prepared statements, parameter bindings, transactions, execution time, rows affected, and errors. Events are streamed to connected TUI clients via gRPC.

MIT