Paul Trowbridge
8cdd88d053
Changes: - Rename app/ directory to jrunner/ (preserves git history) - Update settings.gradle to reference jrunner module - Update readme.md with new paths (jrunner/build/, /opt/jrunner) - Update CLAUDE.md documentation with new file paths Build outputs now named jrunner.zip, jrunner.jar, bin/jrunner instead of generic "app" names. This makes the project structure clearer and aligns module name with project name. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
91 lines
3.4 KiB
Markdown
91 lines
3.4 KiB
Markdown
# CLAUDE.md
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This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
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## Project Overview
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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.
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## Build and Test Commands
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Build the project:
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```bash
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gradle build
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# or use wrapper
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./gradlew build
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```
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Run tests:
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```bash
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gradle test
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# or use wrapper
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./gradlew test
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```
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Build distribution package:
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```bash
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gradle build
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# Creates jrunner/build/distributions/jrunner.zip
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```
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Deploy to /opt (as documented in readme.md):
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```bash
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sudo unzip jrunner/build/distributions/jrunner.zip -d /opt/
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sudo ln -sf /opt/jrunner/bin/jrunner /usr/local/bin/jrunner
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```
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## Architecture
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### Single-File Design
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The entire application logic resides in `jrunner/src/main/java/jrunner/jrunner.java`. This is a monolithic command-line tool with no abstraction layers or separate modules.
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### Data Flow
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1. Parse command-line arguments (-scu, -scn, -scp for source; -dcu, -dcn, -dcp for destination)
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2. Read SQL query from file specified by -sq flag
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3. Connect to source and destination databases via JDBC
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4. Execute source query and fetch results (fetch size: 10,000 rows)
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5. Build batched INSERT statements (250 rows per batch)
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6. Execute batches against destination table specified by -dt flag
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7. Optionally clear target table before insert if -c flag is set
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### Type Handling
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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.
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### Database Drivers
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JDBC drivers are configured in `jrunner/build.gradle`:
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- PostgreSQL: org.postgresql:postgresql:42.5.0
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- IBM AS/400 (JT400): net.sf.jt400:jt400:11.0
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- Microsoft SQL Server: com.microsoft.sqlserver:mssql-jdbc:9.2.0.jre8
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- SQL Server Integrated Auth: com.microsoft.sqlserver:mssql-jdbc_auth:9.2.0.x64
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The AS/400 driver requires explicit Class.forName() registration (line 144).
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## Configuration
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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.
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Command-line flags:
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- `-scu` - source JDBC URL
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- `-scn` - source username
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- `-scp` - source password
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- `-dcu` - destination JDBC URL
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- `-dcn` - destination username
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- `-dcp` - destination password
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- `-sq` - path to source SQL query file
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- `-dt` - fully qualified destination table name
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- `-t` - trim text fields (default: true)
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- `-c` - clear target table before insert (default: true)
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## Key Implementation Details
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### Batch Size
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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.
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### Error Handling
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SQLException handling prints stack trace and exits immediately with System.exit(0). There is no transaction rollback or partial failure recovery.
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### Performance Considerations
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- Result set fetch size is set to 10,000 rows (line 173)
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- Progress counter prints with carriage return for real-time updates
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- Timestamps captured at start (line 174) and end (line 368) for duration tracking
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