multi instance

Author: nicoloboschi

README.md

@@ -8,6 +8,7 @@ Includes **pgvector** for AI/vector workloads out of the box.
 
 - **Zero dependencies** - single binary, no installation required
 - **Embedded PostgreSQL 16** with pgvector pre-installed
+- **Multiple instances** - run multiple PostgreSQL servers simultaneously
 - Works on macOS (Apple Silicon), Linux (x86_64), and Windows (x64)
 - Bundled `psql` client - no separate installation needed
 - Data persists between restarts
@@ -68,6 +69,19 @@ pg0 info
 
 # JSON output
 pg0 info -o json
+
+# Info for a specific instance
+pg0 info --name myapp
+```
+
+### List Instances
+
+```bash
+# List all instances
+pg0 list
+
+# JSON output
+pg0 list -o json
 ```
 
 ### Open psql Shell
@@ -104,6 +118,35 @@ INSERT INTO items (embedding) VALUES ('[0.1, 0.2, ...]');
 SELECT * FROM items ORDER BY embedding <-> '[0.1, 0.2, ...]' LIMIT 5;
 ```
 
+### Multiple Instances
+
+Run multiple PostgreSQL servers simultaneously using named instances:
+
+```bash
+# Start multiple instances on different ports
+pg0 start --name app1 --port 5432
+pg0 start --name app2 --port 5433
+pg0 start --name test --port 5434
+
+# List all instances
+pg0 list
+
+# Get info for a specific instance
+pg0 info --name app1
+
+# Connect to a specific instance
+pg0 psql --name app2
+
+# Stop a specific instance
+pg0 stop --name test
+
+# Stop all (one by one)
+pg0 stop --name app1
+pg0 stop --name app2
+```
+
+Each instance has its own data directory at `~/.pg0/instances/<name>/data/`.
+
 ### Install Additional Extensions
 
 For extensions beyond pgvector:
@@ -130,8 +173,9 @@ pg0 install-extension <name>
 pg0 start [OPTIONS]
 
 Options:
+      --name <NAME>          Instance name [default: default]
   -p, --port <PORT>          Port to listen on [default: 5432]
-  -d, --data-dir <DATA_DIR>  Data directory [default: ~/.pg0/data]
+  -d, --data-dir <DATA_DIR>  Data directory [default: ~/.pg0/instances/<name>/data]
   -u, --username <USERNAME>  Username [default: postgres]
   -P, --password <PASSWORD>  Password [default: postgres]
   -n, --database <DATABASE>  Database name [default: postgres]
@@ -141,7 +185,7 @@ Options:
 
 On first run, pg0 downloads PostgreSQL from [theseus-rs](https://github.com/theseus-rs/postgresql-binaries) and pgvector from pre-compiled binaries. These are cached in `~/.pg0/installation/` for subsequent runs.
 
-Data is stored in `~/.pg0/data/` (or your custom `--data-dir`) and persists between restarts.
+Data is stored in `~/.pg0/instances/<name>/data/` (or your custom `--data-dir`) and persists between restarts.
 
 ## Build from Source