Paul Trowbridge
1392e0a6d8
Documents build commands, architecture, and implementation details to help Claude Code instances understand the codebase structure and data flow. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
94 lines
3.5 KiB
Markdown
94 lines
3.5 KiB
Markdown
# CLAUDE.md
|
|
|
|
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
|
|
|
|
## Project Overview
|
|
|
|
jrunner is a Java CLI tool for migrating data between databases. It reads data from a source database using SQL queries and writes it to a destination table, batching inserts for performance. The tool supports multiple database types via JDBC drivers including PostgreSQL, IBM AS/400, and Microsoft SQL Server.
|
|
|
|
## Build and Test Commands
|
|
|
|
Build the project:
|
|
```bash
|
|
gradle build
|
|
# or use wrapper
|
|
./gradlew build
|
|
```
|
|
|
|
Run tests:
|
|
```bash
|
|
gradle test
|
|
# or use wrapper
|
|
./gradlew test
|
|
```
|
|
|
|
Build distribution package:
|
|
```bash
|
|
gradle build
|
|
# Creates app/build/distributions/app.zip
|
|
```
|
|
|
|
Deploy to /opt (as documented in readme.md):
|
|
```bash
|
|
sudo cp app/build/distributions/app.zip /opt/
|
|
sudo rm -rf /opt/app/
|
|
sudo unzip /opt/app.zip -d /opt/
|
|
sudo rm /opt/app.zip
|
|
sudo chown ptrowbridge:ptrowbridge -R /opt/app/
|
|
```
|
|
|
|
## Architecture
|
|
|
|
### Single-File Design
|
|
The entire application logic resides in `app/src/main/java/jrunner/jrunner.java`. This is a monolithic command-line tool with no abstraction layers or separate modules.
|
|
|
|
### Data Flow
|
|
1. Parse command-line arguments (-scu, -scn, -scp for source; -dcu, -dcn, -dcp for destination)
|
|
2. Read SQL query from file specified by -sq flag
|
|
3. Connect to source and destination databases via JDBC
|
|
4. Execute source query and fetch results (fetch size: 10,000 rows)
|
|
5. Build batched INSERT statements (250 rows per batch)
|
|
6. Execute batches against destination table specified by -dt flag
|
|
7. Optionally clear target table before insert if -c flag is set
|
|
|
|
### Type Handling
|
|
The tool includes explicit handling for different SQL data types in a switch statement (lines 229-312). Supported types include VARCHAR, TEXT, CHAR, CLOB, DATE, TIME, TIMESTAMP, and BIGINT. String types get quote escaping and optional trimming.
|
|
|
|
### Database Drivers
|
|
JDBC drivers are configured in `app/build.gradle`:
|
|
- PostgreSQL: org.postgresql:postgresql:42.5.0
|
|
- IBM AS/400 (JT400): net.sf.jt400:jt400:11.0
|
|
- Microsoft SQL Server: com.microsoft.sqlserver:mssql-jdbc:9.2.0.jre8
|
|
- SQL Server Integrated Auth: com.microsoft.sqlserver:mssql-jdbc_auth:9.2.0.x64
|
|
|
|
The AS/400 driver requires explicit Class.forName() registration (line 144).
|
|
|
|
## Configuration
|
|
|
|
The project uses a YAML configuration format (run.yml) to specify database connections, SQL script paths, and runtime options. However, the main application currently uses command-line arguments instead of parsing this YAML file.
|
|
|
|
Command-line flags:
|
|
- `-scu` - source JDBC URL
|
|
- `-scn` - source username
|
|
- `-scp` - source password
|
|
- `-dcu` - destination JDBC URL
|
|
- `-dcn` - destination username
|
|
- `-dcp` - destination password
|
|
- `-sq` - path to source SQL query file
|
|
- `-dt` - fully qualified destination table name
|
|
- `-t` - trim text fields (default: true)
|
|
- `-c` - clear target table before insert (default: true)
|
|
|
|
## Key Implementation Details
|
|
|
|
### Batch Size
|
|
INSERT statements are batched at 250 rows (hardcoded at line 324). When the batch threshold is reached, sql is prepended with "INSERT INTO {table} VALUES" and executed.
|
|
|
|
### Error Handling
|
|
SQLException handling prints stack trace and exits immediately with System.exit(0). There is no transaction rollback or partial failure recovery.
|
|
|
|
### Performance Considerations
|
|
- Result set fetch size is set to 10,000 rows (line 173)
|
|
- Progress counter prints with carriage return for real-time updates
|
|
- Timestamps captured at start (line 174) and end (line 368) for duration tracking
|