docs: add detailed architecture overview to README

README.md

@@ -4,6 +4,51 @@ Implementation of the SimpleDB database system in Go.
 
 http://www.cs.bc.edu/~sciore/simpledb/
 
+## Architecture Overview
+
+SimpleDB is a teaching database system that implements core database functionality with a PostgreSQL-compatible interface. Here's an overview of its key components:
+
+### Core Components
+
+1. **Storage Layer**
+   - File management for block-level operations
+   - Buffer pool for caching data blocks in memory
+   - Record management and schema definitions
+   - Write-ahead logging for transaction recovery
+
+2. **Index Management**
+   - B-tree indexing implementation
+   - Support for creating and using indexes on table columns
+   - Efficient index scan operations
+
+3. **Query Processing**
+   - SQL parser and lexer
+   - Query planning and optimization with heuristic approach
+   - Various join strategies including merge join
+   - Support for materialization and sorting
+
+4. **Transaction Management**
+   - ACID compliance
+   - BEGIN, COMMIT, and ROLLBACK support
+   - Recovery mechanisms
+
+5. **Metadata Management**
+   - System catalogs management
+   - Table and index definitions tracking
+
+6. **Client Interface**
+   - PostgreSQL wire protocol implementation
+   - Compatible with standard `psql` client
+
+### Features
+
+- Basic SQL operations (CREATE TABLE, INSERT, SELECT, UPDATE, DELETE)
+- JOIN operations and complex queries
+- GROUP BY and aggregation
+- Index-based query optimization
+- Transaction management
+- Block-based storage with buffer management
+
 ## Usage
 
 Launch the SimpleDB server with the following command:
@@ -20,6 +65,6 @@ psql -h localhost -p 45432
 
 ## Supported SQL Commands / Examples
 
-See below files:
+See below files for detailed SQL examples and usage:
 - [internal/testdata/example.sql](internal/testdata/example.sql)
 - [internal/postgres/server_test.go](internal/postgres/server_test.go)