Installation (#223)

* add installation guide

Author: ChuckHend

INSTALLATION.md

@@ -0,0 +1,56 @@
+# Installing pg_vectorize
+
+To install the pg_vectorize extension into an existing Postgres cluster, run the following on the same host as Postgres:
+
+1. Install [Rust](https://www.rust-lang.org/tools/install)
+
+```bash
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+```
+
+2. Install [pgrx](https://github.com/pgcentralfoundation/pgrx)
+
+```bash
+cargo install cargo-pgrx --version 0.13.1 --locked
+
+cargo pgrx init --pg17 $(which pg_config)
+```
+
+3. Clone the repo and install dependencies
+
+```bash
+git clone https://github.com/ChuckHend/pg_vectorize.git
+
+cd pg_vectorize/extension
+
+# install dependencies
+make setup PGRX_PG_CONFIG=$(which pg_config)
+```
+
+4. Compile and install pg_vectorize
+
+```bash
+cargo pgrx install
+```
+
+5. Update `shared_preload_libraries`
+
+Set these values in your postgresql.conf file:
+
+```
+shared_preload_libraries = 'pg_cron, vectorize'
+```
+
+or run this SQL command then restart Postgres:
+
+```sql
+ALTER SYSTEM SET shared_preload_libraries TO 'pg_cron', 'vectorize';
+```
+
+6. Enable the extension
+
+connect to your Postgres instance with something like `psql -U postgres`. Then, run:
+
+```sql
+CREATE EXTENSION vectorize CASCADE;
+```