databasemetadata.java

关系型数据库 Postgresql 6.5.2

  }
  
  /**
   * Can a schema name be used in a data manipulation statement?  Nope.
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsSchemasInDataManipulation() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a schema name be used in a procedure call statement?  Nope.
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsSchemasInProcedureCalls() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a schema be used in a table definition statement?  Nope.
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsSchemasInTableDefinitions() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a schema name be used in an index definition statement?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsSchemasInIndexDefinitions() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a schema name be used in a privilege definition statement?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsSchemasInPrivilegeDefinitions() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a catalog name be used in a data manipulation statement?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsCatalogsInDataManipulation() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a catalog name be used in a procedure call statement?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsCatalogsInProcedureCalls() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a catalog name be used in a table definition statement?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsCatalogsInTableDefinitions() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a catalog name be used in an index definition?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsCatalogsInIndexDefinitions() throws SQLException
  {
    return false;
  }
  
  /**
   * Can a catalog name be used in a privilege definition statement?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsCatalogsInPrivilegeDefinitions() throws SQLException
  {
    return false;
  }
  
  /**
   * We support cursors for gets only it seems.  I dont see a method
   * to get a positioned delete.
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsPositionedDelete() throws SQLException
  {
    return false;			// For now...
  }
  
  /**
   * Is positioned UPDATE supported?
   * 
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsPositionedUpdate() throws SQLException
  {
    return false;			// For now...
  }
  
  public boolean supportsSelectForUpdate() throws SQLException
  {
    // XXX-Not Implemented
    return false;
  }
  
  public boolean supportsStoredProcedures() throws SQLException
  {
    // XXX-Not Implemented
    return false;
  }
  
  public boolean supportsSubqueriesInComparisons() throws SQLException
  {
    // XXX-Not Implemented
    return false;
  }
  
  public boolean supportsSubqueriesInExists() throws SQLException
  {
    // XXX-Not Implemented
    return false;
  }
  
  public boolean supportsSubqueriesInIns() throws SQLException
  {
    // XXX-Not Implemented
    return false;
  }
  
  public boolean supportsSubqueriesInQuantifieds() throws SQLException
  {
    // XXX-Not Implemented
    return false;
  }
  
  public boolean supportsCorrelatedSubqueries() throws SQLException
  {
    // XXX-Not Implemented
    return false;
  }
  
  /**
   * Is SQL UNION supported?  Nope.
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsUnion() throws SQLException
  {
    return false;
  }
  
  /**
   * Is SQL UNION ALL supported?  Nope.
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsUnionAll() throws SQLException
  {
    return false;
  }
  
  /**
   * In PostgreSQL, Cursors are only open within transactions.
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsOpenCursorsAcrossCommit() throws SQLException
  {
    return false;
  }
  
  /**
   * Do we support open cursors across multiple transactions?
   *
   * @return true if so
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsOpenCursorsAcrossRollback() throws SQLException
  {
    return false;
  }
  
  /**
   * Can statements remain open across commits?  They may, but
   * this driver cannot guarentee that.  In further reflection.
   * we are talking a Statement object jere, so the answer is
   * yes, since the Statement is only a vehicle to ExecSQL()
   *
   * @return true if they always remain open; false otherwise
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsOpenStatementsAcrossCommit() throws SQLException
  {
    return true;
  }
  
  /**
   * Can statements remain open across rollbacks?  They may, but
   * this driver cannot guarentee that.  In further contemplation,
   * we are talking a Statement object here, so the answer is yes,
   * since the Statement is only a vehicle to ExecSQL() in Connection
   *
   * @return true if they always remain open; false otherwise
   * @exception SQLException if a database access error occurs
   */
  public boolean supportsOpenStatementsAcrossRollback() throws SQLException
  {
    return true;
  }
  
  /**
   * How many hex characters can you have in an inline binary literal
   *
   * @return the max literal length
   * @exception SQLException if a database access error occurs
   */
  public int getMaxBinaryLiteralLength() throws SQLException
  {
    return 0;				// For now...
  }
  
  /**
   * What is the maximum length for a character literal
   * I suppose it is 8190 (8192 - 2 for the quotes)
   *
   * @return the max literal length
   * @exception SQLException if a database access error occurs
   */
  public int getMaxCharLiteralLength() throws SQLException
  {
    return 8190;
  }
  
  /**
   * Whats the limit on column name length.  The description of
   * pg_class would say '32' (length of pg_class.relname) - we
   * should probably do a query for this....but....
   *
   * @return the maximum column name length
   * @exception SQLException if a database access error occurs
   */
  public int getMaxColumnNameLength() throws SQLException
  {
    return 32;
  }
  
  /**
   * What is the maximum number of columns in a "GROUP BY" clause?
   *
   * @return the max number of columns
   * @exception SQLException if a database access error occurs	
   */
  public int getMaxColumnsInGroupBy() throws SQLException
  {
    return getMaxColumnsInTable();
  }
  
  /**
   * What's the maximum number of columns allowed in an index?
   * 6.0 only allowed one column, but 6.1 introduced multi-column
   * indices, so, theoretically, its all of them.
   *
   * @return max number of columns
   * @exception SQLException if a database access error occurs
   */
  public int getMaxColumnsInIndex() throws SQLException
  {
    return getMaxColumnsInTable();
  }
  
  /**
   * What's the maximum number of columns in an "ORDER BY clause?
   * Theoretically, all of them!
   *
   * @return the max columns
   * @exception SQLException if a database access error occurs
   */
  public int getMaxColumnsInOrderBy() throws SQLException
  {
    return getMaxColumnsInTable();
  }
  
  /**
   * What is the maximum number of columns in a "SELECT" list?
   * Theoretically, all of them!
   *
   * @return the max columns
   * @exception SQLException if a database access error occurs
   */
  public int getMaxColumnsInSelect() throws SQLException
  {
    return getMaxColumnsInTable();
  }
  
  /**
   * What is the maximum number of columns in a table? From the
   * create_table(l) manual page...
   *
   * <p>"The new class is created as a heap with no initial data.  A
   * class can have no more than 1600 attributes (realistically,
   * this is limited by the fact that tuple sizes must be less than
   * 8192 bytes)..."
   *
   * @return the max columns
   * @exception SQLException if a database access error occurs
   */
  public int getMaxColumnsInTable() throws SQLException
  {
    return 1600;
  }
  
  /**
   * How many active connection can we have at a time to this
   * database?  Well, since it depends on postmaster, which just
   * does a listen() followed by an accept() and fork(), its
   * basically very high.  Unless the system runs out of processes,
   * it can be 65535 (the number of aux. ports on a TCP/IP system).
   * I will return 8192 since that is what even the largest system
   * can realistically handle,
   *
   * @return the maximum number of connections
   * @exception SQLException if a database access error occurs
   */
  public int getMaxConnections() throws SQLException
  {
    return 8192;
  }
  
  /**
   * What is the maximum cursor name length (the same as all
   * the other F***** identifiers!)
   *
   * @return max cursor name length in bytes
   * @exception SQLException if a database access error occurs
   */
  public int getMaxCursorNameLength() throws SQLException
  {
    return 32;
  }
  
  /**
   * What is the maximum length of an index (in bytes)?  Now, does
   * the spec. mean name of an index (in which case its 32, the 
   * same as a table) or does it mean length of an index element
   * (in which case its 8192, the size of a row) or does it mean
   * the number of rows it can access (in which case it 2^32 - 
   * a 4 byte OID number)?  I think its the length of an index
   * element, personally, so Im setting it to 8192.
   *
   * @return max index length in bytes
   * @exception SQLException if a database access error occurs
   */
  public int getMaxIndexLength() throws SQLException
  {
    return 8192;
  }
  
  public int getMaxSchemaNameLength() throws SQLException
  {
    // XXX-Not Implemented
    return 0;
  }
  
  /**
   * What is the maximum length of a procedure name?
   * (length of pg_proc.proname used) - again, I really
   * should do a query here to get it.
   *
   * @return the max name length in bytes
   * @exception SQLException if a database access error occurs
   */
  public int getMaxProcedureNameLength() throws SQLException
  {
    return 32;