DP44/GIT Migration.md

# SVN → Git Migration Plan: BRANCH_MAINT_4_04

## Overview

**Source:** `http://build:8080/svn/Software/Views/DTS.Suite/branches/BRANCH_MAINT_4_04`
**Target:** New Git repository
**Scope:** Single project branch, full history preservation
**Estimated Time:** 1-2 hours

---

## SVN Repository Structure

```
http://build:8080/svn/Software/
└── Views/
    └── DTS.Suite/
        └── branches/
            └── BRANCH_MAINT_4_04/   ← This working copy
                ├── Common/
                ├── DataPRO/
                ├── DataPRO_sql/
                ├── DTS Viewer/
                └── ...
```

Note: Non-standard SVN layout (Views/... instead of trunk/branches at root).

---

## Prerequisites

```bash
# Install tools on macOS
brew install git svn

# Verify network access
ping build
```

---

## Phase 1: Author Mapping (~10 min)

### 1.1 Extract SVN Authors

```bash
svn log http://build:8080/svn/Software/Views/DTS.Suite/branches/BRANCH_MAINT_4_04 --quiet | grep "^r" | awk '{print $3}' | sort -u > svn-authors.txt
```

### 1.2 Create authors.txt

Transform the extracted list into Git format:

```
svn_username = Full Name <email@example.com>
jdoe = John Doe <john@company.com>
tsmith = Tom Smith <tom@company.com>
```

**Format:** `svn_username = Git Name <email>`

---

## Phase 2: Binary Exclusion Strategy

### 2.1 Patterns to Exclude

Based on repository analysis (366 binary files identified):

| Category | Pattern | Reason |
|----------|---------|--------|
| Build outputs | `**/bin/`, `**/obj/` | Generated by build |
| DLLs | `*.dll` | NuGet restore or build output |
| Executables | `*.exe` | Build output or redistributable |
| Installers | `*.msi` | Build artifact |
| Packages | `*.nupkg`, `**/packages/` | NuGet restore |
| Debug files | `*.pdb` | Build output |
| Database files | `*.mdf`, `*.ldf` | Development data |
| PDFs (large) | `*.pdf` | Documentation, not source |

### 2.2 .gitignore Template

```gitignore
# Build outputs
**/bin/
**/obj/
*.dll
*.exe
*.pdb

# Installers & redistributables
**/DataPRO Installer/**/*.msi
**/DataPRO Installer/**/*.exe
**/Redistributables/

# Database files
*.mdf
*.ldf

# Packages (restore via NuGet)
**/packages/
*.nupkg

# IDE & OS files
.vs/
.idea/
*.user
*.suo
.DS_Store

# Generated files
*.Designer.cs
*.g.cs
*.g.i.cs

# AI enrichment (optional)
enriched/
enriched-qwen3-coder-next/
.vectordb/
```

### 2.3 Third-Party DLLs Decision

**Question:** Are any third-party DLLs required in source control (not available via NuGet)?

If yes, track exceptions:
```
!Common/DTS.CommonCore/lib/ThirdParty/required.dll
```

---

## Phase 3: Migration (~30-90 min)

### 3.1 Clone SVN to Git

```bash
git svn clone \
  --authors-file=authors.txt \
  --no-metadata \
  --prefix=svn/ \
  http://build:8080/svn/Software/Views/DTS.Suite/branches/BRANCH_MAINT_4_04 \
  BRANCH_MAINT_4_04-git
```

**Flags:**
- `--authors-file`: Maps SVN users → Git identities
- `--no-metadata`: Cleaner commits (no `git-svn-id` lines)
- `--prefix=svn/`: Remote-tracking branch naming

### 3.2 Alternative: git svn init + fetch (for better control)

If the clone is interrupted or you need more control:

```bash
mkdir BRANCH_MAINT_4_04-git
cd BRANCH_MAINT_4_04-git
git svn init --authors-file=../authors.txt --no-metadata \
  http://build:8080/svn/Software/Views/DTS.Suite/branches/BRANCH_MAINT_4_04
git svn fetch
```

---

## Phase 4: Post-Clone Cleanup (~15 min)

### 4.1 Navigate to New Repo

```bash
cd BRANCH_MAINT_4_04-git
```

### 4.2 Add .gitignore

```bash
# Create .gitignore with content from Phase 2.2
```

### 4.3 Remove Binaries from Git Tracking

```bash
# Remove build outputs (keep locally)
git rm -r --cached '**/bin/'
git rm -r --cached '**/obj/'
git rm -r --cached '**/packages/'

# Remove binaries
git rm --cached '*.dll'
git rm --cached '*.exe'
git rm --cached '*.msi'
git rm --cached '*.pdb'
git rm --cached '*.mdf'

# Commit cleanup
git add .gitignore
git commit -m "Add .gitignore, remove binaries from tracking"
```

### 4.4 Clean Repository Size (Optional)

```bash
# Remove large files from entire history (destructive)
git filter-branch --force --index-filter \
  'git rm --cached --ignore-unmatch *.dll *.exe *.msi *.mdf' \
  --prune-empty --tag-name-filter cat -- --all
```

Then garbage collect:
```bash
git reflog expire --expire=now --all
git gc --prune=now --aggressive
```

---

## Phase 5: Push to Remote (~5 min)

### 5.1 Create Remote Repository

Options:
- **GitHub:** `gh repo create datapro --private`
- **GitLab:** Create via UI
- **Self-hosted:** `git init --bare` on server

### 5.2 Push

```bash
git remote add origin git@github.com:your-org/datapro.git
git branch -M main
git push -u origin main
```

---

## Phase 6: Verification

```bash
# Check history
git log --oneline | head -20

# Check file count
git ls-files | wc -l

# Check for missed binaries
git ls-files | grep -E '\.(dll|exe|msi|mdf)$'

# Verify author mapping
git log --format='%an <%ae>' | sort -u
```

---

## Timeline Summary

| Step | Time | Risk |
|------|------|------|
| Install tools | 5 min | Low |
| Extract authors & create mapping | 10 min | Low |
| git svn clone | 30-90 min | Medium (network) |
| Cleanup & .gitignore | 15 min | Low |
| Push to remote | 5 min | Low |

**Total:** ~1-2 hours

---

## Open Questions

1. **Migration machine:** Run on Mac or machine on same network as SVN server?
2. **Git hosting:** GitHub, GitLab, or self-hosted?
3. **Third-party DLLs:** Any that must stay in source control?
4. **Private files:** Any secrets/configs to exclude before push?

---

## Rollback Plan

If migration fails:
1. Original SVN working copy is unaffected
2. Delete `BRANCH_MAINT_4_04-git/` and retry
3. SVN server remains authoritative until Git push succeeds

---

## Post-Migration

- [ ] Update CI/CD pipelines to use Git
- [ ] Notify team of new repository location
- [ ] Set SVN branch to read-only (optional)
- [ ] Document new workflow in team wiki