External Catalog Operations

/**
 * Hive-backed external catalog implementation for metastore operations
 * @param conf Spark configuration
 * @param hadoopConf Hadoop configuration
 */
class HiveExternalCatalog(conf: SparkConf, hadoopConf: Configuration) extends ExternalCatalog {
  lazy val client: HiveClient
}

import org.apache.spark.sql.hive.HiveExternalCatalog
import org.apache.spark.SparkConf
import org.apache.hadoop.conf.Configuration

val conf = new SparkConf()
val hadoopConf = new Configuration()
val catalog = new HiveExternalCatalog(conf, hadoopConf)

// Access the underlying Hive client
val hiveClient = catalog.client

/**
 * Create a new database in the Hive metastore
 * @param dbDefinition Database definition with metadata
 * @param ignoreIfExists If true, don't fail if database already exists
 */
def createDatabase(dbDefinition: CatalogDatabase, ignoreIfExists: Boolean): Unit

/**
 * Drop a database from the Hive metastore
 * @param db Database name
 * @param ignoreIfNotExists If true, don't fail if database doesn't exist
 * @param cascade If true, drop all tables in the database
 */
def dropDatabase(db: String, ignoreIfNotExists: Boolean, cascade: Boolean): Unit

/**
 * Modify an existing database's metadata
 * @param dbDefinition Updated database definition
 */
def alterDatabase(dbDefinition: CatalogDatabase): Unit

/**
 * Get database metadata
 * @param db Database name
 * @return Database definition
 */
def getDatabase(db: String): CatalogDatabase

/**
 * Check if a database exists
 * @param db Database name  
 * @return True if database exists
 */
def databaseExists(db: String): Boolean

/**
 * List all databases
 * @return Sequence of database names
 */
def listDatabases(): Seq[String]

/**
 * List databases matching a pattern
 * @param pattern Pattern to match (SQL LIKE pattern)
 * @return Sequence of matching database names
 */
def listDatabases(pattern: String): Seq[String]

/**
 * Set the current database
 * @param db Database name to set as current
 */
def setCurrentDatabase(db: String): Unit

import org.apache.spark.sql.catalyst.catalog.CatalogDatabase

// Create a database
val dbDef = CatalogDatabase(
  name = "my_database",
  description = "Test database",
  locationUri = new URI("hdfs://namenode:9000/user/hive/warehouse/my_database.db"),
  properties = Map.empty
)
catalog.createDatabase(dbDef, ignoreIfExists = true)

// List databases
val databases = catalog.listDatabases()
println(s"Available databases: ${databases.mkString(", ")}")

// Get database info
val dbInfo = catalog.getDatabase("my_database")
println(s"Database location: ${dbInfo.locationUri}")

/**
 * Create a new table in the Hive metastore
 * @param tableDefinition Complete table definition
 * @param ignoreIfExists If true, don't fail if table already exists
 */
def createTable(tableDefinition: CatalogTable, ignoreIfExists: Boolean): Unit

/**
 * Drop a table from the Hive metastore
 * @param db Database name
 * @param table Table name  
 * @param ignoreIfNotExists If true, don't fail if table doesn't exist
 * @param purge If true, delete table data immediately
 */
def dropTable(db: String, table: String, ignoreIfNotExists: Boolean, purge: Boolean): Unit

/**
 * Rename a table
 * @param db Database name
 * @param oldName Current table name
 * @param newName New table name
 */
def renameTable(db: String, oldName: String, newName: String): Unit

/**
 * Modify table metadata
 * @param tableDefinition Updated table definition
 */
def alterTable(tableDefinition: CatalogTable): Unit

/**
 * Alter table's data schema
 * @param db Database name
 * @param table Table name
 * @param newDataSchema New schema structure
 */
def alterTableDataSchema(db: String, table: String, newDataSchema: StructType): Unit

/**
 * Update table statistics
 * @param db Database name
 * @param table Table name
 * @param stats Optional statistics to set
 */
def alterTableStats(db: String, table: String, stats: Option[CatalogStatistics]): Unit

/**
 * Get table metadata
 * @param db Database name
 * @param table Table name
 * @return Complete table definition
 */
def getTable(db: String, table: String): CatalogTable

/**
 * Get multiple tables by name
 * @param db Database name
 * @param tables Sequence of table names
 * @return Sequence of table definitions
 */
def getTablesByName(db: String, tables: Seq[String]): Seq[CatalogTable]

/**
 * Check if a table exists
 * @param db Database name
 * @param table Table name
 * @return True if table exists
 */
def tableExists(db: String, table: String): Boolean

/**
 * List all tables in a database
 * @param db Database name
 * @return Sequence of table names
 */
def listTables(db: String): Seq[String]

/**
 * List tables matching a pattern
 * @param db Database name
 * @param pattern Pattern to match (SQL LIKE pattern)
 * @return Sequence of matching table names
 */
def listTables(db: String, pattern: String): Seq[String]

/**
 * List all views in a database
 * @param db Database name
 * @return Sequence of view names
 */
def listViews(db: String): Seq[String]

/**
 * List views matching a pattern
 * @param db Database name
 * @param pattern Pattern to match (SQL LIKE pattern)
 * @return Sequence of matching view names
 */
def listViews(db: String, pattern: String): Seq[String]

import org.apache.spark.sql.catalyst.catalog.{CatalogTable, CatalogTableType}
import org.apache.spark.sql.types._

// Create a table
val schema = StructType(Seq(
  StructField("id", IntegerType, nullable = false),
  StructField("name", StringType, nullable = true),
  StructField("created_at", TimestampType, nullable = true)
))

val tableDef = CatalogTable(
  identifier = TableIdentifier("users", Some("my_database")),
  tableType = CatalogTableType.MANAGED,
  storage = CatalogStorageFormat.empty.copy(
    inputFormat = Some("org.apache.hadoop.mapred.TextInputFormat"),
    outputFormat = Some("org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat"),
    serde = Some("org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe")
  ),
  schema = schema
)

catalog.createTable(tableDef, ignoreIfExists = true)

// List tables
val tables = catalog.listTables("my_database")
println(s"Tables: ${tables.mkString(", ")}")

// Get table info
val tableInfo = catalog.getTable("my_database", "users")
println(s"Table schema: ${tableInfo.schema}")

/**
 * Load data into a table
 * @param db Database name
 * @param table Table name
 * @param loadPath Path to data files
 * @param isOverwrite If true, overwrite existing data
 * @param isSrcLocal If true, source is local filesystem
 */
def loadTable(db: String, table: String, loadPath: String, 
              isOverwrite: Boolean, isSrcLocal: Boolean): Unit

/**
 * Load data into a partition
 * @param db Database name
 * @param table Table name
 * @param loadPath Path to data files
 * @param partition Partition specification
 * @param isOverwrite If true, overwrite existing data
 * @param inheritTableSpecs If true, inherit table specifications
 * @param isSrcLocal If true, source is local filesystem
 */
def loadPartition(db: String, table: String, loadPath: String, 
                  partition: TablePartitionSpec, isOverwrite: Boolean, 
                  inheritTableSpecs: Boolean, isSrcLocal: Boolean): Unit

/**
 * Load data into dynamic partitions
 * @param db Database name
 * @param table Table name
 * @param loadPath Path to data files
 * @param partition Partition specification
 * @param replace If true, replace existing partitions
 * @param numDP Number of dynamic partitions
 */
def loadDynamicPartitions(db: String, table: String, loadPath: String, 
                         partition: TablePartitionSpec, replace: Boolean, 
                         numDP: Int): Unit

/**
 * Create table partitions
 * @param db Database name
 * @param table Table name
 * @param parts Sequence of partition definitions
 * @param ignoreIfExists If true, don't fail if partitions already exist
 */
def createPartitions(db: String, table: String, parts: Seq[CatalogTablePartition], 
                    ignoreIfExists: Boolean): Unit

/**
 * Drop table partitions
 * @param db Database name
 * @param table Table name
 * @param parts Sequence of partition specifications
 * @param ignoreIfNotExists If true, don't fail if partitions don't exist
 * @param purge If true, delete partition data immediately
 * @param retainData If true, keep partition data files
 */
def dropPartitions(db: String, table: String, parts: Seq[TablePartitionSpec], 
                  ignoreIfNotExists: Boolean, purge: Boolean, retainData: Boolean): Unit

/**
 * Rename table partitions
 * @param db Database name
 * @param table Table name
 * @param specs Current partition specifications
 * @param newSpecs New partition specifications
 */
def renamePartitions(db: String, table: String, specs: Seq[TablePartitionSpec], 
                    newSpecs: Seq[TablePartitionSpec]): Unit

/**
 * Modify partition metadata
 * @param db Database name
 * @param table Table name
 * @param parts Updated partition definitions
 */
def alterPartitions(db: String, table: String, parts: Seq[CatalogTablePartition]): Unit

/**
 * Get partition metadata
 * @param db Database name
 * @param table Table name
 * @param spec Partition specification
 * @return Partition definition
 */
def getPartition(db: String, table: String, spec: TablePartitionSpec): CatalogTablePartition

/**
 * Get partition metadata optionally
 * @param db Database name
 * @param table Table name
 * @param spec Partition specification
 * @return Optional partition definition
 */
def getPartitionOption(db: String, table: String, spec: TablePartitionSpec): Option[CatalogTablePartition]

/**
 * List partition names
 * @param db Database name
 * @param table Table name
 * @param partialSpec Optional partial partition specification for filtering
 * @return Sequence of partition names
 */
def listPartitionNames(db: String, table: String, 
                      partialSpec: Option[TablePartitionSpec]): Seq[String]

/**
 * List partitions
 * @param db Database name
 * @param table Table name
 * @param partialSpec Optional partial partition specification for filtering
 * @return Sequence of partition definitions
 */
def listPartitions(db: String, table: String, 
                  partialSpec: Option[TablePartitionSpec]): Seq[CatalogTablePartition]

/**
 * List partitions matching filter predicates
 * @param db Database name
 * @param table Table name
 * @param predicates Filter expressions
 * @param defaultTimeZoneId Default timezone for date/time operations
 * @return Sequence of matching partition definitions
 */
def listPartitionsByFilter(db: String, table: String, predicates: Seq[Expression], 
                          defaultTimeZoneId: String): Seq[CatalogTablePartition]

/**
 * Create a user-defined function
 * @param db Database name
 * @param funcDefinition Function definition
 */
def createFunction(db: String, funcDefinition: CatalogFunction): Unit

/**
 * Drop a user-defined function
 * @param db Database name
 * @param funcName Function name
 */
def dropFunction(db: String, funcName: String): Unit

/**
 * Modify function metadata
 * @param db Database name
 * @param funcDefinition Updated function definition
 */
def alterFunction(db: String, funcDefinition: CatalogFunction): Unit

/**
 * Rename a function
 * @param db Database name
 * @param oldName Current function name
 * @param newName New function name
 */
def renameFunction(db: String, oldName: String, newName: String): Unit

/**
 * Get function metadata
 * @param db Database name
 * @param funcName Function name
 * @return Function definition
 */
def getFunction(db: String, funcName: String): CatalogFunction

/**
 * Check if a function exists
 * @param db Database name
 * @param funcName Function name
 * @return True if function exists
 */
def functionExists(db: String, funcName: String): Boolean

/**
 * List functions matching a pattern
 * @param db Database name
 * @param pattern Pattern to match (SQL LIKE pattern)
 * @return Sequence of matching function names
 */
def listFunctions(db: String, pattern: String): Seq[String]

object HiveExternalCatalog {
  // Metadata key constants
  val SPARK_SQL_PREFIX: String
  val DATASOURCE_PREFIX: String
  val DATASOURCE_PROVIDER: String
  val DATASOURCE_SCHEMA: String
  val STATISTICS_PREFIX: String
  val STATISTICS_TOTAL_SIZE: String
  val STATISTICS_NUM_ROWS: String
  val TABLE_PARTITION_PROVIDER: String
  val CREATED_SPARK_VERSION: String
  val EMPTY_DATA_SCHEMA: StructType
  
  /**
   * Check if a table is a data source table
   * @param table Table definition
   * @return True if table uses Spark data source format
   */
  def isDatasourceTable(table: CatalogTable): Boolean
  
  /**
   * Check if a data type is compatible with Hive
   * @param dt Data type to check
   * @return True if type is Hive-compatible
   */
  def isHiveCompatibleDataType(dt: DataType): Boolean
}