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//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.impala.catalog;

import java.util.Comparator;
import java.util.List;

import org.apache.hadoop.hive.metastore.api.Database;
import org.apache.hadoop.hive.metastore.api.Table;
import org.apache.impala.analysis.ColumnDef;
import org.apache.impala.analysis.KuduPartitionParam;
import org.apache.impala.thrift.TDatabase;
import org.apache.impala.thrift.TFunctionCategory;
import org.apache.impala.util.PatternMatcher;

/**
 * Frontend interface for interacting with a database.
 */
public interface FeDb extends HasName {

  Comparator<FeDb> NAME_COMPARATOR = new Comparator<FeDb>() {
    @Override
    public int compare(FeDb db1, FeDb db2) {
      return db1.getName().compareTo(db2.getName());
    }
  };

  /**
   * @return the name of the database
   */
  @Override
  String getName();

  /**
   * @return the metastore.api.Database object this Database was created from,
   * or null if it is not related to a hive database such as builtins_db.
   */
  Database getMetaStoreDb();

  /**
   * @return true if the database contains a table with the given name
   */
  boolean containsTable(String tableName);

  /**
   * @return the table with the given name
   */
  FeTable getTable(String tbl);

  /**
   * @return the table with the given name if it's completely loaded in the cache.
   * Otherwise, return an IncompleteTable for it.
   */
  FeTable getTableIfCached(String tbl);

  /**
   * @return the names of the tables within this database
   */
  List<String> getAllTableNames();

  /**
   * @return true if this is a system database (i.e. cannot be dropped,
   * modified, etc)
   */
  boolean isSystemDb();

  // TODO(todd): can we simplify the many related 'getFunctions' calls
  // in this interface?

  /**
   * @see Catalog#getFunction(Function, Function.CompareMode)
   */
  public Function getFunction(Function desc, Function.CompareMode mode);

  /**
   * @return all functions with the given name
   */
  List<Function> getFunctions(String functionName);

  /**
   * @return all functions with the given category and name
   */
  List<Function> getFunctions(TFunctionCategory category, String function);

  /**
   * @return all functions with the given category that match the given pattern
   */
  List<Function> getFunctions(TFunctionCategory category,
      PatternMatcher patternMatcher);

  /**
   * @return the number of functions in this database.
   */
  int numFunctions();

  /**
   * @see Catalog#containsFunction(org.apache.impala.analysis.FunctionName)
   */
  boolean containsFunction(String function);

  /**
   * @return the Thrift-serialized structure for this database
   */
  TDatabase toThrift();

  /**
   * Create a target Kudu table object for CTAS.
   */
  FeKuduTable createKuduCtasTarget(Table msTbl, List<ColumnDef> columnDefs,
      List<ColumnDef> primaryKeyColumnDefs,
      List<KuduPartitionParam> kuduPartitionParams);

  /**
   * Create a target FS table object for CTAS.
   */
  FeFsTable createFsCtasTarget(Table msTbl) throws CatalogException;

  /**
   * @return the owner user for this database. Returns null if one does not exist.
   */
  String getOwnerUser();
}