Add unique constraints safely in SQLAlchemy

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```

Install this rule for wispbit

Add this rule to wispbit and it will run when you open a pull request

Install this rule for Coderabbit

Copy the configuration below and add it to your repository as .coderabbit.yml in your project root.

reviews:
  path_instructions:
    - path: "*.py"
      instructions: |
                
        When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
        
        Bad:
        
        ```python
        def upgrade():
            # Directly creating a unique constraint can block reads and writes
            op.create_unique_constraint('users_email_unique', 'users', ['email'])
        ```
        
        Good:
        
        ```python
        # Migration 1: Create unique index concurrently
        
        def upgrade():
            # Create the unique index concurrently (non-blocking)
            op.create_index(
                'users_email_unique_idx',
                'users',
                ['email'],
                unique=True,
                postgresql_concurrently=True
            )
        ```
        
        ```python
        # Migration 2: Add constraint using existing index
        
        def upgrade():
            # Add the unique constraint using the existing index
            op.create_unique_constraint(
                'users_email_unique',
                'users',
                ['email'],
                postgresql_using_index='users_email_unique_idx'
            )
        ```
        

Install this rule for Greptile

Greptile rules can be added through the web interface. Please see this documentation for details on how to add custom rules and context.

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```

File Path Patterns:

*.py

Install this rule for GitHub Copilot

Copilot instructions can be added through the interface. See the documentation for details on how to create coding guidelines.

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```

File Path Patterns:

*.py

Install this rule for Graphite Diamond

Diamond custom rules can be added through the interface. See the documentation for details on how to create custom rules.

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```

File Path Patterns:

*.py

Use with Cline

Copy the rule below and ask Cline to review your code using this rule

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```

Use with OpenAI Codex

Copy the rule below and ask OpenAI Codex to review your code using this rule

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```

Use with Cursor

Copy the rule below and ask Cursor to review your code using this rule

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```

Use with Claude Code

Copy the rule below and ask Claude Code to review your code using this rule

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```

Install this rule for Windsurf

To set up rules for Windsurf Reviews, please see this documentation

When adding unique constraints that could affect large tables, create the unique index concurrently first to avoid blocking reads and writes during the migration.
Bad:
```python
def upgrade():
    # Directly creating a unique constraint can block reads and writes
    op.create_unique_constraint('users_email_unique', 'users', ['email'])
```
Good:
```python
# Migration 1: Create unique index concurrently
def upgrade():
    # Create the unique index concurrently (non-blocking)
    op.create_index(
        'users_email_unique_idx',
        'users',
        ['email'],
        unique=True,
        postgresql_concurrently=True
    )
```
```python
# Migration 2: Add constraint using existing index
def upgrade():
    # Add the unique constraint using the existing index
    op.create_unique_constraint(
        'users_email_unique',
        'users',
        ['email'],
        postgresql_using_index='users_email_unique_idx'
    )
```