Schema Management

/**
 * Interface for managing graph database schema
 */
public interface Schema {
    
    /**
     * Create an index builder for the specified label
     * @param label Label to create index for
     * @return Index creator for building the index
     */
    IndexCreator indexFor(Label label);
    
    /**
     * Create a constraint builder for the specified label
     * @param label Label to create constraint for
     * @return Constraint creator for building the constraint
     */
    ConstraintCreator constraintFor(Label label);
    
    /**
     * Create a constraint builder for the specified relationship type
     * @param relationshipType Relationship type to create constraint for
     * @return Constraint creator for building the constraint
     */
    ConstraintCreator constraintFor(RelationshipType relationshipType);
    
    /**
     * Get all indexes in the database
     * @return Iterable of all index definitions
     */
    Iterable<IndexDefinition> getIndexes();
    
    /**
     * Get indexes for a specific label
     * @param label Label to get indexes for
     * @return Iterable of index definitions for the label
     */
    Iterable<IndexDefinition> getIndexes(Label label);
    
    /**
     * Get all constraints in the database
     * @return Iterable of all constraint definitions
     */
    Iterable<ConstraintDefinition> getConstraints();
    
    /**
     * Get constraints for a specific label
     * @param label Label to get constraints for
     * @return Iterable of constraint definitions for the label
     */
    Iterable<ConstraintDefinition> getConstraints(Label label);
    
    /**
     * Get constraints for a specific relationship type
     * @param relationshipType Relationship type to get constraints for
     * @return Iterable of constraint definitions for the relationship type
     */
    Iterable<ConstraintDefinition> getConstraints(RelationshipType relationshipType);
    
    /**
     * Get the state of a specific index
     * @param index Index to check state for
     * @return Current index state
     */
    IndexState getIndexState(IndexDefinition index);
    
    /**
     * Get the population progress of an index
     * @param index Index to check progress for
     * @return Population progress percentage (0.0 to 1.0)
     */
    double getIndexPopulationProgress(IndexDefinition index);
    
    /**
     * Get the failure message for a failed index
     * @param index Index to get failure message for
     * @return Failure message, or null if index is not failed
     */
    String getIndexFailure(IndexDefinition index);
    
    /**
     * Wait for an index to be online
     * @param index Index to wait for
     * @param duration Maximum time to wait
     * @param unit Time unit for duration
     * @throws IllegalStateException if index fails to come online
     */
    void awaitIndexOnline(IndexDefinition index, long duration, TimeUnit unit);
    
    /**
     * Wait for all indexes to be online
     * @param duration Maximum time to wait
     * @param unit Time unit for duration
     */
    void awaitIndexesOnline(long duration, TimeUnit unit);
}

import org.neo4j.graphdb.schema.Schema;
import org.neo4j.graphdb.schema.IndexDefinition;
import org.neo4j.graphdb.schema.ConstraintDefinition;
import java.util.concurrent.TimeUnit;

try (Transaction tx = graphDb.beginTx()) {
    Schema schema = tx.schema();
    
    // List all existing indexes
    System.out.println("Existing indexes:");
    for (IndexDefinition index : schema.getIndexes()) {
        System.out.println("  " + index.getLabel() + ": " + index.getPropertyKeys());
        System.out.println("    State: " + schema.getIndexState(index));
    }
    
    // List all existing constraints
    System.out.println("Existing constraints:");
    for (ConstraintDefinition constraint : schema.getConstraints()) {
        System.out.println("  " + constraint.getLabel() + ": " + 
                          constraint.getPropertyKeys() + " (" + 
                          constraint.getConstraintType() + ")");
    }
    
    tx.commit();
}

/**
 * Builder for creating database indexes
 */
public interface IndexCreator {
    
    /**
     * Specify a property key for the index
     * @param propertyKey Property key to index
     * @return This creator for method chaining
     */
    IndexCreator on(String propertyKey);
    
    /**
     * Set the index type (if supported)
     * @param indexType Type of index to create
     * @return This creator for method chaining
     */
    IndexCreator withIndexType(IndexType indexType);
    
    /**
     * Set the index configuration
     * @param indexConfig Configuration map for the index
     * @return This creator for method chaining
     */
    IndexCreator withIndexConfiguration(Map<IndexSetting, Object> indexConfig);
    
    /**
     * Set a name for the index
     * @param indexName Name for the index
     * @return This creator for method chaining
     */
    IndexCreator withName(String indexName);
    
    /**
     * Create the index
     * @return Index definition for the created index
     */
    IndexDefinition create();
}

try (Transaction tx = graphDb.beginTx()) {
    Schema schema = tx.schema();
    
    // Create a simple property index
    IndexDefinition nameIndex = schema.indexFor(label("Person"))
        .on("name")
        .create();
    
    // Create a composite index on multiple properties
    IndexDefinition personIndex = schema.indexFor(label("Person"))
        .on("firstName")
        .on("lastName")
        .withName("person_full_name_index")
        .create();
    
    // Create a text index for full-text search
    IndexDefinition textIndex = schema.indexFor(label("Article"))
        .on("title")
        .on("content")
        .withIndexType(IndexType.FULLTEXT)
        .withName("article_fulltext_index")
        .create();
    
    tx.commit();
}

// Wait for indexes to come online
try (Transaction tx = graphDb.beginTx()) {
    Schema schema = tx.schema();
    
    // Wait for a specific index
    schema.awaitIndexOnline(nameIndex, 10, TimeUnit.SECONDS);
    
    // Wait for all indexes
    schema.awaitIndexesOnline(30, TimeUnit.SECONDS);
    
    tx.commit();
}

/**
 * Builder for creating database constraints
 */
public interface ConstraintCreator {
    
    /**
     * Assert that a property must be unique
     * @param propertyKey Property key that must be unique
     * @return This creator for method chaining
     */
    ConstraintCreator assertPropertyIsUnique(String propertyKey);
    
    /**
     * Assert that a property must exist (not null)
     * @param propertyKey Property key that must exist
     * @return This creator for method chaining
     */
    ConstraintCreator assertPropertyExists(String propertyKey);
    
    /**
     * Assert that a property must be a specific type
     * @param propertyKey Property key to type-check
     * @param propertyType Expected property type
     * @return This creator for method chaining
     */
    ConstraintCreator assertPropertyIsOfType(String propertyKey, PropertyType propertyType);
    
    /**
     * Set a name for the constraint
     * @param constraintName Name for the constraint
     * @return This creator for method chaining
     */
    ConstraintCreator withName(String constraintName);
    
    /**
     * Create the constraint
     * @return Constraint definition for the created constraint
     */
    ConstraintDefinition create();
}

try (Transaction tx = graphDb.beginTx()) {
    Schema schema = tx.schema();
    
    // Create uniqueness constraint
    ConstraintDefinition emailConstraint = schema.constraintFor(label("User"))
        .assertPropertyIsUnique("email")
        .withName("unique_user_email")
        .create();
    
    // Create existence constraint
    ConstraintDefinition nameConstraint = schema.constraintFor(label("Person"))
        .assertPropertyExists("name")
        .withName("person_must_have_name")
        .create();
    
    // Create composite uniqueness constraint
    ConstraintDefinition userConstraint = schema.constraintFor(label("User"))
        .assertPropertyIsUnique("username")
        .assertPropertyIsUnique("domain")
        .withName("unique_user_in_domain")
        .create();
    
    tx.commit();
}

/**
 * Definition of a database index
 */
public interface IndexDefinition {
    
    /**
     * Get the label this index is associated with
     * @return Label for the index
     */
    Label getLabel();
    
    /**
     * Get the property keys included in this index
     * @return Iterable of property keys
     */
    Iterable<String> getPropertyKeys();
    
    /**
     * Get the name of this index
     * @return Index name, or null if not named
     */
    String getName();
    
    /**
     * Get the type of this index
     * @return Index type
     */
    IndexType getIndexType();
    
    /**
     * Check if this is a composite index (multiple properties)
     * @return true if composite index, false otherwise
     */
    boolean isCompositeIndex();
    
    /**
     * Check if this is a multi-token index (multiple labels)
     * @return true if multi-token index, false otherwise
     */
    boolean isMultiTokenIndex();
    
    /**
     * Drop this index
     */
    void drop();
}

/**
 * Definition of a database constraint
 */
public interface ConstraintDefinition {
    
    /**
     * Get the label this constraint is associated with
     * @return Label for the constraint
     */
    Label getLabel();
    
    /**
     * Get the property keys included in this constraint
     * @return Iterable of property keys
     */
    Iterable<String> getPropertyKeys();
    
    /**
     * Get the name of this constraint
     * @return Constraint name, or null if not named
     */
    String getName();
    
    /**
     * Get the type of this constraint
     * @return Constraint type (UNIQUENESS, NODE_PROPERTY_EXISTENCE, etc.)
     */
    ConstraintType getConstraintType();
    
    /**
     * Check if this is a composite constraint (multiple properties)
     * @return true if composite constraint, false otherwise
     */
    boolean isCompositeConstraint();
    
    /**
     * Drop this constraint
     */
    void drop();
}

/**
 * State of an index
 */
public enum IndexState {
    /** Index is being created */
    POPULATING,
    
    /** Index is online and available for use */
    ONLINE,
    
    /** Index creation failed */
    FAILED
}

/**
 * Types of indexes supported
 */
public enum IndexType {
    /** Standard B-tree index for exact lookups */
    BTREE,
    
    /** Full-text search index */
    FULLTEXT,
    
    /** Text index for string operations */
    TEXT,
    
    /** Range index for numeric and temporal data */
    RANGE,
    
    /** Point index for spatial data */
    POINT
}

/**
 * Types of constraints supported
 */
public enum ConstraintType {
    /** Uniqueness constraint */
    UNIQUENESS,
    
    /** Node property existence constraint */
    NODE_PROPERTY_EXISTENCE,
    
    /** Relationship property existence constraint */
    RELATIONSHIP_PROPERTY_EXISTENCE,
    
    /** Node key constraint (unique + existence) */
    NODE_KEY,
    
    /** Property type constraint */
    PROPERTY_TYPE
}

/**
 * Property types for type constraints
 */
public enum PropertyType {
    BOOLEAN,
    BYTE,
    SHORT,
    INT,
    LONG,
    FLOAT,
    DOUBLE,
    STRING,
    BYTE_ARRAY,
    SHORT_ARRAY,
    INT_ARRAY,
    LONG_ARRAY,
    FLOAT_ARRAY,
    DOUBLE_ARRAY,
    STRING_ARRAY,
    BOOLEAN_ARRAY,
    POINT,
    DATE,
    TIME,
    LOCAL_TIME,
    DATETIME,
    LOCAL_DATETIME,
    DURATION
}

// Complete schema management workflow
try (Transaction tx = graphDb.beginTx()) {
    Schema schema = tx.schema();
    
    // Create indexes for performance
    IndexDefinition userEmailIndex = schema.indexFor(label("User"))
        .on("email")
        .withName("user_email_index")
        .create();
    
    IndexDefinition productNameIndex = schema.indexFor(label("Product"))
        .on("name")
        .withIndexType(IndexType.TEXT)
        .create();
    
    // Create constraints for data integrity
    ConstraintDefinition userEmailUnique = schema.constraintFor(label("User"))
        .assertPropertyIsUnique("email")
        .create();
    
    ConstraintDefinition userNameExists = schema.constraintFor(label("User"))
        .assertPropertyExists("name")
        .create();
    
    tx.commit();
}

// Monitor index creation progress
try (Transaction tx = graphDb.beginTx()) {
    Schema schema = tx.schema();
    
    for (IndexDefinition index : schema.getIndexes()) {
        IndexState state = schema.getIndexState(index);
        System.out.println("Index " + index.getName() + ": " + state);
        
        if (state == IndexState.POPULATING) {
            double progress = schema.getIndexPopulationProgress(index);
            System.out.println("  Progress: " + (progress * 100) + "%");
        } else if (state == IndexState.FAILED) {
            String failure = schema.getIndexFailure(index);
            System.out.println("  Failure: " + failure);
        }
    }
    
    tx.commit();
}

// Drop indexes and constraints
try (Transaction tx = graphDb.beginTx()) {
    Schema schema = tx.schema();
    
    // Find and drop specific index
    for (IndexDefinition index : schema.getIndexes(label("User"))) {
        if (index.getPropertyKeys().iterator().next().equals("email")) {
            index.drop();
            System.out.println("Dropped index on User.email");
            break;
        }
    }
    
    // Find and drop specific constraint
    for (ConstraintDefinition constraint : schema.getConstraints(label("User"))) {
        if (constraint.getConstraintType() == ConstraintType.UNIQUENESS) {
            constraint.drop();
            System.out.println("Dropped uniqueness constraint");
            break;
        }
    }
    
    tx.commit();
}