text: # maxdb/base.py
  # Copyright (C) 2005-2012 the SQLAlchemy authors and contributors <see AUTHORS file>
  #
  # This module is part of SQLAlchemy and is released under
  # the MIT License: http://www.opensource.org/licenses/mit-license.php
  
  """Support for the MaxDB database.
  
  This dialect is *not* ported to SQLAlchemy 0.6 or 0.7.
  
  This dialect is *not* tested on SQLAlchemy 0.6 or 0.7.
  
  Overview
  --------
  
  The ``maxdb`` dialect is **experimental** and has only been tested on 7.6.03.007
  and 7.6.00.037.  Of these, **only 7.6.03.007 will work** with SQLAlchemy's ORM.
  The earlier version has severe ``LEFT JOIN`` limitations and will return
  incorrect results from even very simple ORM queries.
  
  Only the native Python DB-API is currently supported.  ODBC driver support
  is a future enhancement.
  
  Connecting
  ----------
  
  The username is case-sensitive.  If you usually connect to the
  database with sqlcli and other tools in lower case, you likely need to
  use upper case for DB-API.
  
  Implementation Notes
  --------------------
  
  With the 7.6.00.37 driver and Python 2.5, it seems that all DB-API
  generated exceptions are broken and can cause Python to crash.
  
  For 'somecol.in_([])' to work, the IN operator's generation must be changed
  to cast 'NULL' to a numeric, i.e. NUM(NULL).  The DB-API doesn't accept a
  bind parameter there, so that particular generation must inline the NULL value,
  which depends on [ticket:807].
  
  The DB-API is very picky about where bind params may be used in queries.
  
  Bind params for some functions (e.g. MOD) need type information supplied.
  The dialect does not yet do this automatically.
  
  Max will occasionally throw up 'bad sql, compile again' exceptions for
  perfectly valid SQL.  The dialect does not currently handle these, more
  research is needed.
  
  MaxDB 7.5 and Sap DB <= 7.4 reportedly do not support schemas.  A very
  slightly different version of this dialect would be required to support
  those versions, and can easily be added if there is demand.  Some other
  required components such as an Max-aware 'old oracle style' join compiler
  (thetas with (+) outer indicators) are already done and available for
  integration- email the devel list if you're interested in working on
  this.
  
  Versions tested: 7.6.03.07 and 7.6.00.37, native Python DB-API
  
  * MaxDB has severe limitations on OUTER JOINs, which are essential to ORM
    eager loading. And rather than raise an error if a SELECT can't be serviced,
    the database simply returns incorrect results.
  * Version 7.6.03.07 seems to JOIN properly, however the docs do not show the
    OUTER restrictions being lifted (as of this writing), and no changelog is
    available to confirm either. If you are using a different server version and
    your tasks require the ORM or any semi-advanced SQL through the SQL layer,
    running the SQLAlchemy test suite against your database is HIGHLY
    recommended before you begin.
  * Version 7.6.00.37 is LHS/RHS sensitive in `FROM lhs LEFT OUTER JOIN rhs ON
    lhs.col=rhs.col` vs `rhs.col=lhs.col`!
  * Version 7.6.00.37 is confused by `SELECT DISTINCT col as alias FROM t ORDER
    BY col` - these aliased, DISTINCT, ordered queries need to be re-written to
    order by the alias name.
  * Version 7.6.x supports creating a SAVEPOINT but not its RELEASE.
  * MaxDB supports autoincrement-style columns (DEFAULT SERIAL) and independent
    sequences. When including a DEFAULT SERIAL column in an insert, 0 needs to
    be inserted rather than NULL to generate a value.
  * MaxDB supports ANSI and "old Oracle style" theta joins with (+) outer join
    indicators.
  * The SQLAlchemy dialect is schema-aware and probably won't function correctly
    on server versions (pre-7.6?). Support for schema-less server versions could
    be added if there's call.
  * ORDER BY is not supported in subqueries. LIMIT is not supported in
    subqueries. In 7.6.00.37, TOP does work in subqueries, but without limit not
    so useful. OFFSET does not work in 7.6 despite being in the docs. Row number
    tricks in WHERE via ROWNO may be possible but it only seems to allow
    less-than comparison!
  * Version 7.6.03.07 can't LIMIT if a derived table is in FROM: `SELECT * FROM
    (SELECT * FROM a) LIMIT 2`
  * MaxDB does not support sql's CAST and can only usefullly cast two types.
    There isn't much implicit type conversion, so be precise when creating
    `PassiveDefaults` in DDL generation: `'3'` and `3` aren't the same.
  
  sapdb.dbapi
  ^^^^^^^^^^^
  
  * As of 2007-10-22 the Python 2.4 and 2.5 compatible versions of the DB-API
    are no longer available. A forum posting at SAP states that the Python
    driver will be available again "in the future". The last release from MySQL
    AB works if you can find it.
  * sequence.NEXTVAL skips every other value!
  * No rowcount for executemany()
  * If an INSERT into a table with a DEFAULT SERIAL column inserts the results
    of a function `INSERT INTO t VALUES (LENGTH('foo'))`, the cursor won't have
    the serial id. It needs to be manually yanked from tablename.CURRVAL.
  * Super-duper picky about where bind params can be placed. Not smart about
    converting Python types for some functions, such as `MOD(5, ?)`.
  * LONG (text, binary) values in result sets are read-once. The dialect uses a
    caching RowProxy when these types are present.
  * Connection objects seem like they want to be either `close()`d or garbage
    collected, but not both. There's a warning issued but it seems harmless.
  
  
  """
  import datetime, itertools, re
  
  from sqlalchemy import exc, schema, sql, util, processors
  from sqlalchemy.sql import operators as sql_operators, expression as sql_expr
  from sqlalchemy.sql import compiler, visitors
  from sqlalchemy.engine import base as engine_base, default, reflection
  from sqlalchemy import types as sqltypes
  
  
  class _StringType(sqltypes.String):
      _type = None
  
      def __init__(self, length=None, encoding=None, **kw):
          super(_StringType, self).__init__(length=length, **kw)
          self.encoding = encoding
  
      def bind_processor(self, dialect):
          if self.encoding == 'unicode':
              return None
          else:
              def process(value):
                  if isinstance(value, unicode):
                      return value.encode(dialect.encoding)
                  else:
                      return value
              return process
  
      def result_processor(self, dialect, coltype):
          #XXX: this code is probably very slow and one should try (if at all
          # possible) to determine the correct code path on a per-connection
          # basis (ie, here in result_processor, instead of inside the processor
          # function itself) and probably also use a few generic
          # processors, or possibly per query (though there is no mechanism
          # for that yet).
          def process(value):
              while True:
                  if value is None:
                      return None
                  elif isinstance(value, unicode):
                      return value
                  elif isinstance(value, str):
                      if self.convert_unicode or dialect.convert_unicode:
                          return value.decode(dialect.encoding)
                      else:
                          return value
                  elif hasattr(value, 'read'):
                      # some sort of LONG, snarf and retry
                      value = value.read(value.remainingLength())
                      continue
                  else:
                      # unexpected type, return as-is
                      return value
          return process
  
  
  class MaxString(_StringType):
      _type = 'VARCHAR'
  
  
  class MaxUnicode(_StringType):
      _type = 'VARCHAR'
  
      def __init__(self, length=None, **kw):
          kw['encoding'] = 'unicode'
          super(MaxUnicode, self).__init__(length=length, **kw)
  
  
  class MaxChar(_StringType):
      _type = 'CHAR'
  
  
  class MaxText(_StringType):
      _type = 'LONG'
  
      def __init__(self, length=None, **kw):
          super(MaxText, self).__init__(length, **kw)
  
      def get_col_spec(self):
          spec = 'LONG'
          if self.encoding is not None:
              spec = ' '.join((spec, self.encoding))
          elif self.convert_unicode:
              spec = ' '.join((spec, 'UNICODE'))
  
          return spec
  
  
  class MaxNumeric(sqltypes.Numeric):
      """The FIXED (also NUMERIC, DECIMAL) data type."""
  
      def __init__(self, precision=None, scale=None, **kw):
          kw.setdefault('asdecimal', True)
          super(MaxNumeric, self).__init__(scale=scale, precision=precision,
                                           **kw)
  
      def bind_processor(self, dialect):
          return None
  
  
  class MaxTimestamp(sqltypes.DateTime):
      def bind_processor(self, dialect):
          def process(value):
              if value is None:
                  return None
              elif isinstance(value, basestring):
                  return value
              elif dialect.datetimeformat == 'internal':
                  ms = getattr(value, 'microsecond', 0)
                  return value.strftime("%Y%m%d%H%M%S" + ("%06u" % ms))
              elif dialect.datetimeformat == 'iso':
                  ms = getattr(value, 'microsecond', 0)
                  return value.strftime("%Y-%m-%d %H:%M:%S." + ("%06u" % ms))
              else:
                  raise exc.InvalidRequestError(
                      "datetimeformat '%s' is not supported." % (
                      dialect.datetimeformat,))
          return process
  
      def result_processor(self, dialect, coltype):
          if dialect.datetimeformat == 'internal':
              def process(value):
                  if value is None:
                      return None
                  else:
                      return datetime.datetime(
                          *[int(v)
                            for v in (value[0:4], value[4:6], value[6:8],
                                      value[8:10], value[10:12], value[12:14],
                                      value[14:])])
          elif dialect.datetimeformat == 'iso':
              def process(value):
                  if value is None:
                      return None
                  else:
                      return datetime.datetime(
                          *[int(v)
                            for v in (value[0:4], value[5:7], value[8:10],
                                      value[11:13], value[14:16], value[17:19],
                                      value[20:])])
          else:
              raise exc.InvalidRequestError(
                  "datetimeformat '%s' is not supported." % 
                  dialect.datetimeformat)
          return process
  
  
  class MaxDate(sqltypes.Date):
      def bind_processor(self, dialect):
          def process(value):
              if value is None:
                  return None
              elif isinstance(value, basestring):
                  return value
              elif dialect.datetimeformat == 'internal':
                  return value.strftime("%Y%m%d")
              elif dialect.datetimeformat == 'iso':
                  return value.strftime("%Y-%m-%d")
              else:
                  raise exc.InvalidRequestError(
                      "datetimeformat '%s' is not supported." % (
                      dialect.datetimeformat,))
          return process
  
      def result_processor(self, dialect, coltype):
          if dialect.datetimeformat == 'internal':
              def process(value):
                  if value is None:
                      return None
                  else:
                      return datetime.date(int(value[0:4]), int(value[4:6]), 
                                           int(value[6:8]))
          elif dialect.datetimeformat == 'iso':
              def process(value):
                  if value is None:
                      return None
                  else:
                      return datetime.date(int(value[0:4]), int(value[5:7]), 
                                           int(value[8:10]))
          else:
              raise exc.InvalidRequestError(
                  "datetimeformat '%s' is not supported." % 
                  dialect.datetimeformat)
          return process
  
  
  class MaxTime(sqltypes.Time):
      def bind_processor(self, dialect):
          def process(value):
              if value is None:
                  return None
              elif isinstance(value, basestring):
                  return value
              elif dialect.datetimeformat == 'internal':
                  return value.strftime("%H%M%S")
              elif dialect.datetimeformat == 'iso':
                  return value.strftime("%H-%M-%S")
              else:
                  raise exc.InvalidRequestError(
                      "datetimeformat '%s' is not supported." % (
                      dialect.datetimeformat,))
          return process
  
      def result_processor(self, dialect, coltype):
          if dialect.datetimeformat == 'internal':
              def process(value):
                  if value is None:
                      return None
                  else:
                      return datetime.time(int(value[0:4]), int(value[4:6]), 
                                           int(value[6:8]))
          elif dialect.datetimeformat == 'iso':
              def process(value):
                  if value is None:
                      return None
                  else:
                      return datetime.time(int(value[0:4]), int(value[5:7]),
                                           int(value[8:10]))
          else:
              raise exc.InvalidRequestError(
                  "datetimeformat '%s' is not supported." % 
                  dialect.datetimeformat)
          return process
  
  
  class MaxBlob(sqltypes.LargeBinary):
      def bind_processor(self, dialect):
          return processors.to_str
  
      def result_processor(self, dialect, coltype):
          def process(value):
              if value is None:
                  return None
              else:
                  return value.read(value.remainingLength())
          return process
  
  class MaxDBTypeCompiler(compiler.GenericTypeCompiler):
      def _string_spec(self, string_spec, type_):
          if type_.length is None:
              spec = 'LONG'
          else:
              spec = '%s(%s)' % (string_spec, type_.length)
  
          if getattr(type_, 'encoding'):
              spec = ' '.join([spec, getattr(type_, 'encoding').upper()])
          return spec
  
      def visit_text(self, type_):
          spec = 'LONG'
          if getattr(type_, 'encoding', None):
              spec = ' '.join((spec, type_.encoding))
          elif type_.convert_unicode:
              spec = ' '.join((spec, 'UNICODE'))
  
          return spec
  
      def visit_char(self, type_):
          return self._string_spec("CHAR", type_)
  
      def visit_string(self, type_):
          return self._string_spec("VARCHAR", type_)
  
      def visit_large_binary(self, type_):
          return "LONG BYTE"
  
      def visit_numeric(self, type_):
          if type_.scale and type_.precision:
              return 'FIXED(%s, %s)' % (type_.precision, type_.scale)
          elif type_.precision:
              return 'FIXED(%s)' % type_.precision
          else:
              return 'INTEGER'
  
      def visit_BOOLEAN(self, type_):
          return "BOOLEAN"
  
  colspecs = {
      sqltypes.Numeric: MaxNumeric,
      sqltypes.DateTime: MaxTimestamp,
      sqltypes.Date: MaxDate,
      sqltypes.Time: MaxTime,
      sqltypes.String: MaxString,
      sqltypes.Unicode:MaxUnicode,
      sqltypes.LargeBinary: MaxBlob,
      sqltypes.Text: MaxText,
      sqltypes.CHAR: MaxChar,
      sqltypes.TIMESTAMP: MaxTimestamp,
      sqltypes.BLOB: MaxBlob,
      sqltypes.Unicode: MaxUnicode,
      }
  
  ischema_names = {
      'boolean': sqltypes.BOOLEAN,
      'char': sqltypes.CHAR,
      'character': sqltypes.CHAR,
      'date': sqltypes.DATE,
      'fixed': sqltypes.Numeric,
      'float': sqltypes.FLOAT,
      'int': sqltypes.INT,
      'integer': sqltypes.INT,
      'long binary': sqltypes.BLOB,
      'long unicode': sqltypes.Text,
      'long': sqltypes.Text,
      'long': sqltypes.Text,
      'smallint': sqltypes.SmallInteger,
      'time': sqltypes.Time,
      'timestamp': sqltypes.TIMESTAMP,
      'varchar': sqltypes.VARCHAR,
      }
  
  # TODO: migrate this to sapdb.py
  class MaxDBExecutionContext(default.DefaultExecutionContext):
      def post_exec(self):
          # DB-API bug: if there were any functions as values,
          # then do another select and pull CURRVAL from the
          # autoincrement column's implicit sequence... ugh
          if self.compiled.isinsert and not self.executemany:
              table = self.compiled.statement.table
              index, serial_col = _autoserial_column(table)
  
              if serial_col and (not self.compiled._safeserial or
                                 not(self._last_inserted_ids) or
                                 self._last_inserted_ids[index] in (None, 0)):
                  if table.schema:
                      sql = "SELECT %s.CURRVAL FROM DUAL" % (
                          self.compiled.preparer.format_table(table))
                  else:
                      sql = "SELECT CURRENT_SCHEMA.%s.CURRVAL FROM DUAL" % (
                          self.compiled.preparer.format_table(table))
  
                  rs = self.cursor.execute(sql)
                  id = rs.fetchone()[0]
  
                  if not self._last_inserted_ids:
                      # This shouldn't ever be > 1?  Right?
                      self._last_inserted_ids = \
                        [None] * len(table.primary_key.columns)
                  self._last_inserted_ids[index] = id
  
          super(MaxDBExecutionContext, self).post_exec()
  
      def get_result_proxy(self):
          if self.cursor.description is not None:
              for column in self.cursor.description:
                  if column[1] in ('Long Binary', 'Long', 'Long Unicode'):
                      return MaxDBResultProxy(self)
          return engine_base.ResultProxy(self)
  
      @property
      def rowcount(self):
          if hasattr(self, '_rowcount'):
              return self._rowcount
          else:
              return self.cursor.rowcount
  
      def fire_sequence(self, seq):
          if seq.optional:
              return None
          return self._execute_scalar("SELECT %s.NEXTVAL FROM DUAL" % (
              self.dialect.identifier_preparer.format_sequence(seq)))
  
  class MaxDBCachedColumnRow(engine_base.RowProxy):
      """A RowProxy that only runs result_processors once per column."""
  
      def __init__(self, parent, row):
          super(MaxDBCachedColumnRow, self).__init__(parent, row)
          self.columns = {}
          self._row = row
          self._parent = parent
  
      def _get_col(self, key):
          if key not in self.columns:
              self.columns[key] = self._parent._get_col(self._row, key)
          return self.columns[key]
  
      def __iter__(self):
          for i in xrange(len(self._row)):
              yield self._get_col(i)
  
      def __repr__(self):
          return repr(list(self))
  
      def __eq__(self, other):
          return ((other is self) or
                  (other == tuple([self._get_col(key)
                                   for key in xrange(len(self._row))])))
      def __getitem__(self, key):
          if isinstance(key, slice):
              indices = key.indices(len(self._row))
              return tuple([self._get_col(i) for i in xrange(*indices)])
          else:
              return self._get_col(key)
  
      def __getattr__(self, name):
          try:
              return self._get_col(name)
          except KeyError:
              raise AttributeError(name)
  
  
  class MaxDBResultProxy(engine_base.ResultProxy):
      _process_row = MaxDBCachedColumnRow
  
  class MaxDBCompiler(compiler.SQLCompiler):
  
      function_conversion = {
          'CURRENT_DATE': 'DATE',
          'CURRENT_TIME': 'TIME',
          'CURRENT_TIMESTAMP': 'TIMESTAMP',
          }
  
      # These functions must be written without parens when called with no
      # parameters.  e.g. 'SELECT DATE FROM DUAL' not 'SELECT DATE() FROM DUAL'
      bare_functions = set([
          'CURRENT_SCHEMA', 'DATE', 'FALSE', 'SYSDBA', 'TIME', 'TIMESTAMP',
          'TIMEZONE', 'TRANSACTION', 'TRUE', 'USER', 'UID', 'USERGROUP',
          'UTCDATE', 'UTCDIFF'])
  
      def visit_mod(self, binary, **kw):
          return "mod(%s, %s)" % \
                      (self.process(binary.left), self.process(binary.right))
  
      def default_from(self):
          return ' FROM DUAL'
  
      def for_update_clause(self, select):
          clause = select.for_update
          if clause is True:
              return " WITH LOCK EXCLUSIVE"
          elif clause is None:
              return ""
          elif clause == "read":
              return " WITH LOCK"
          elif clause == "ignore":
              return " WITH LOCK (IGNORE) EXCLUSIVE"
          elif clause == "nowait":
              return " WITH LOCK (NOWAIT) EXCLUSIVE"
          elif isinstance(clause, basestring):
              return " WITH LOCK %s" % clause.upper()
          elif not clause:
              return ""
          else:
              return " WITH LOCK EXCLUSIVE"
  
      def function_argspec(self, fn, **kw):
          if fn.name.upper() in self.bare_functions:
              return ""
          elif len(fn.clauses) > 0:
              return compiler.SQLCompiler.function_argspec(self, fn, **kw)
          else:
              return ""
  
      def visit_function(self, fn, **kw):
          transform = self.function_conversion.get(fn.name.upper(), None)
          if transform:
              fn = fn._clone()
              fn.name = transform
          return super(MaxDBCompiler, self).visit_function(fn, **kw)
  
      def visit_cast(self, cast, **kwargs):
          # MaxDB only supports casts * to NUMERIC, * to VARCHAR or
          # date/time to VARCHAR.  Casts of LONGs will fail.
          if isinstance(cast.type, (sqltypes.Integer, sqltypes.Numeric)):
              return "NUM(%s)" % self.process(cast.clause)
          elif isinstance(cast.type, sqltypes.String):
              return "CHR(%s)" % self.process(cast.clause)
          else:
              return self.process(cast.clause)
  
      def visit_sequence(self, sequence):
          if sequence.optional:
              return None
          else:
              return (
                  self.dialect.identifier_preparer.format_sequence(sequence) +
                  ".NEXTVAL")
  
      class ColumnSnagger(visitors.ClauseVisitor):
          def __init__(self):
              self.count = 0
              self.column = None
          def visit_column(self, column):
              self.column = column
              self.count += 1
  
      def _find_labeled_columns(self, columns, use_labels=False):
          labels = {}
          for column in columns:
              if isinstance(column, basestring):
                  continue
              snagger = self.ColumnSnagger()
              snagger.traverse(column)
              if snagger.count == 1:
                  if isinstance(column, sql_expr._Label):
                      labels[unicode(snagger.column)] = column.name
                  elif use_labels:
                      labels[unicode(snagger.column)] = column._label
  
          return labels
  
      def order_by_clause(self, select, **kw):
          order_by = self.process(select._order_by_clause, **kw)
  
          # ORDER BY clauses in DISTINCT queries must reference aliased
          # inner columns by alias name, not true column name.
          if order_by and getattr(select, '_distinct', False):
              labels = self._find_labeled_columns(select.inner_columns,
                                                  select.use_labels)
              if labels:
                  for needs_alias in labels.keys():
                      r = re.compile(r'(^| )(%s)(,| |$)' %
                                     re.escape(needs_alias))
                      order_by = r.sub((r'\1%s\3' % labels[needs_alias]),
                                       order_by)
  
          # No ORDER BY in subqueries.
          if order_by:
              if self.is_subquery():
                  # It's safe to simply drop the ORDER BY if there is no
                  # LIMIT.  Right?  Other dialects seem to get away with
                  # dropping order.
                  if select._limit:
                      raise exc.CompileError(
                          "MaxDB does not support ORDER BY in subqueries")
                  else:
                      return ""
              return " ORDER BY " + order_by
          else:
              return ""
  
      def get_select_precolumns(self, select):
          # Convert a subquery's LIMIT to TOP
          sql = select._distinct and 'DISTINCT ' or ''
          if self.is_subquery() and select._limit:
              if select._offset:
                  raise exc.InvalidRequestError(
                      'MaxDB does not support LIMIT with an offset.')
              sql += 'TOP %s ' % select._limit
          return sql
  
      def limit_clause(self, select):
          # The docs say offsets are supported with LIMIT.  But they're not.
          # TODO: maybe emulate by adding a ROWNO/ROWNUM predicate?
          # TODO: does MaxDB support bind params for LIMIT / TOP ?
          if self.is_subquery():
              # sub queries need TOP
              return ''
          elif select._offset:
              raise exc.InvalidRequestError(
                  'MaxDB does not support LIMIT with an offset.')
          else:
              return ' \n LIMIT %s' % (select._limit,)
  
      def visit_insert(self, insert):
          self.isinsert = True
          self._safeserial = True
  
          colparams = self._get_colparams(insert)
          for value in (insert.parameters or {}).itervalues():
              if isinstance(value, sql_expr.Function):
                  self._safeserial = False
                  break
  
          return ''.join(('INSERT INTO ',
                           self.preparer.format_table(insert.table),
                           ' (',
                           ', '.join([self.preparer.format_column(c[0])
                                      for c in colparams]),
                           ') VALUES (',
                           ', '.join([c[1] for c in colparams]),
                           ')'))
  
  
  class MaxDBIdentifierPreparer(compiler.IdentifierPreparer):
      reserved_words = set([
          'abs', 'absolute', 'acos', 'adddate', 'addtime', 'all', 'alpha',
          'alter', 'any', 'ascii', 'asin', 'atan', 'atan2', 'avg', 'binary',
          'bit', 'boolean', 'byte', 'case', 'ceil', 'ceiling', 'char',
          'character', 'check', 'chr', 'column', 'concat', 'constraint', 'cos',
          'cosh', 'cot', 'count', 'cross', 'curdate', 'current', 'curtime',
          'database', 'date', 'datediff', 'day', 'dayname', 'dayofmonth',
          'dayofweek', 'dayofyear', 'dec', 'decimal', 'decode', 'default',
          'degrees', 'delete', 'digits', 'distinct', 'double', 'except',
          'exists', 'exp', 'expand', 'first', 'fixed', 'float', 'floor', 'for',
          'from', 'full', 'get_objectname', 'get_schema', 'graphic', 'greatest',
          'group', 'having', 'hex', 'hextoraw', 'hour', 'ifnull', 'ignore',
          'index', 'initcap', 'inner', 'insert', 'int', 'integer', 'internal',
          'intersect', 'into', 'join', 'key', 'last', 'lcase', 'least', 'left',
          'length', 'lfill', 'list', 'ln', 'locate', 'log', 'log10', 'long',
          'longfile', 'lower', 'lpad', 'ltrim', 'makedate', 'maketime',
          'mapchar', 'max', 'mbcs', 'microsecond', 'min', 'minute', 'mod',
          'month', 'monthname', 'natural', 'nchar', 'next', 'no', 'noround',
          'not', 'now', 'null', 'num', 'numeric', 'object', 'of', 'on',
          'order', 'packed', 'pi', 'power', 'prev', 'primary', 'radians',
          'real', 'reject', 'relative', 'replace', 'rfill', 'right', 'round',
          'rowid', 'rowno', 'rpad', 'rtrim', 'second', 'select', 'selupd',
          'serial', 'set', 'show', 'sign', 'sin', 'sinh', 'smallint', 'some',
          'soundex', 'space', 'sqrt', 'stamp', 'statistics', 'stddev',
          'subdate', 'substr', 'substring', 'subtime', 'sum', 'sysdba',
          'table', 'tan', 'tanh', 'time', 'timediff', 'timestamp', 'timezone',
          'to', 'toidentifier', 'transaction', 'translate', 'trim', 'trunc',
          'truncate', 'ucase', 'uid', 'unicode', 'union', 'update', 'upper',
          'user', 'usergroup', 'using', 'utcdate', 'utcdiff', 'value', 'values',
          'varchar', 'vargraphic', 'variance', 'week', 'weekofyear', 'when',
          'where', 'with', 'year', 'zoned' ])
  
      def _normalize_name(self, name):
          if name is None:
              return None
          if name.isupper():
              lc_name = name.lower()
              if not self._requires_quotes(lc_name):
                  return lc_name
          return name
  
      def _denormalize_name(self, name):
          if name is None:
              return None
          elif (name.islower() and
                not self._requires_quotes(name)):
              return name.upper()
          else:
              return name
  
      def _maybe_quote_identifier(self, name):
          if self._requires_quotes(name):
              return self.quote_identifier(name)
          else:
              return name
  
  
  class MaxDBDDLCompiler(compiler.DDLCompiler):
      def get_column_specification(self, column, **kw):
          colspec = [self.preparer.format_column(column),
                     self.dialect.type_compiler.process(column.type)]
  
          if not column.nullable:
              colspec.append('NOT NULL')
  
          default = column.default
          default_str = self.get_column_default_string(column)
  
          # No DDL default for columns specified with non-optional sequence-
          # this defaulting behavior is entirely client-side. (And as a
          # consequence, non-reflectable.)
          if (default and isinstance(default, schema.Sequence) and
              not default.optional):
              pass
          # Regular default
          elif default_str is not None:
              colspec.append('DEFAULT %s' % default_str)
          # Assign DEFAULT SERIAL heuristically
          elif column.primary_key and column.autoincrement:
              # For SERIAL on a non-primary key member, use
              # DefaultClause(text('SERIAL'))
              try:
                  first = [c for c in column.table.primary_key.columns
                           if (c.autoincrement and
                               (isinstance(c.type, sqltypes.Integer) or
                                (isinstance(c.type, MaxNumeric) and
                                 c.type.precision)) and
                               not c.foreign_keys)].pop(0)
                  if column is first:
                      colspec.append('DEFAULT SERIAL')
              except IndexError:
                  pass
          return ' '.join(colspec)
  
      def get_column_default_string(self, column):
          if isinstance(column.server_default, schema.DefaultClause):
              if isinstance(column.default.arg, basestring):
                  if isinstance(column.type, sqltypes.Integer):
                      return str(column.default.arg)
                  else:
                      return "'%s'" % column.default.arg
              else:
                  return unicode(self._compile(column.default.arg, None))
          else:
              return None
  
      def visit_create_sequence(self, create):
          """Creates a SEQUENCE.
  
          TODO: move to module doc?
  
          start
            With an integer value, set the START WITH option.
  
          increment
            An integer value to increment by.  Default is the database default.
  
          maxdb_minvalue
          maxdb_maxvalue
            With an integer value, sets the corresponding sequence option.
  
          maxdb_no_minvalue
          maxdb_no_maxvalue
            Defaults to False.  If true, sets the corresponding sequence option.
  
          maxdb_cycle
            Defaults to False.  If true, sets the CYCLE option.
  
          maxdb_cache
            With an integer value, sets the CACHE option.
  
          maxdb_no_cache
            Defaults to False.  If true, sets NOCACHE.
          """
          sequence = create.element
  
          if (not sequence.optional and
              (not self.checkfirst or
               not self.dialect.has_sequence(self.connection, sequence.name))):
  
              ddl = ['CREATE SEQUENCE',
                     self.preparer.format_sequence(sequence)]
  
              sequence.increment = 1
  
              if sequence.increment is not None:
                  ddl.extend(('INCREMENT BY', str(sequence.increment)))
  
              if sequence.start is not None:
                  ddl.extend(('START WITH', str(sequence.start)))
  
              opts = dict([(pair[0][6:].lower(), pair[1])
                           for pair in sequence.kwargs.items()
                           if pair[0].startswith('maxdb_')])
  
              if 'maxvalue' in opts:
                  ddl.extend(('MAXVALUE', str(opts['maxvalue'])))
              elif opts.get('no_maxvalue', False):
                  ddl.append('NOMAXVALUE')
              if 'minvalue' in opts:
                  ddl.extend(('MINVALUE', str(opts['minvalue'])))
              elif opts.get('no_minvalue', False):
                  ddl.append('NOMINVALUE')
  
              if opts.get('cycle', False):
                  ddl.append('CYCLE')
  
              if 'cache' in opts:
                  ddl.extend(('CACHE', str(opts['cache'])))
              elif opts.get('no_cache', False):
                  ddl.append('NOCACHE')
  
              return ' '.join(ddl)
  
  
  class MaxDBDialect(default.DefaultDialect):
      name = 'maxdb'
      supports_alter = True
      supports_unicode_statements = True
      max_identifier_length = 32
      supports_sane_rowcount = True
      supports_sane_multi_rowcount = False
  
      preparer = MaxDBIdentifierPreparer
      statement_compiler = MaxDBCompiler
      ddl_compiler = MaxDBDDLCompiler
      execution_ctx_cls = MaxDBExecutionContext
  
      ported_sqla_06 = False
  
      colspecs = colspecs
      ischema_names = ischema_names
  
      # MaxDB-specific
      datetimeformat = 'internal'
  
      def __init__(self, _raise_known_sql_errors=False, **kw):
          super(MaxDBDialect, self).__init__(**kw)
          self._raise_known = _raise_known_sql_errors
  
          if self.dbapi is None:
              self.dbapi_type_map = {}
          else:
              self.dbapi_type_map = {
                  'Long Binary': MaxBlob(),
                  'Long byte_t': MaxBlob(),
                  'Long Unicode': MaxText(),
                  'Timestamp': MaxTimestamp(),
                  'Date': MaxDate(),
                  'Time': MaxTime(),
                  datetime.datetime: MaxTimestamp(),
                  datetime.date: MaxDate(),
                  datetime.time: MaxTime(),
              }
  
      def do_execute(self, cursor, statement, parameters, context=None):
          res = cursor.execute(statement, parameters)
          if isinstance(res, int) and context is not None:
              context._rowcount = res
  
      def do_release_savepoint(self, connection, name):
          # Does MaxDB truly support RELEASE SAVEPOINT <id>?  All my attempts
          # produce "SUBTRANS COMMIT/ROLLBACK not allowed without SUBTRANS
          # BEGIN SQLSTATE: I7065"
          # Note that ROLLBACK TO works fine.  In theory, a RELEASE should
          # just free up some transactional resources early, before the overall
          # COMMIT/ROLLBACK so omitting it should be relatively ok.
          pass
  
      def _get_default_schema_name(self, connection):
          return self.identifier_preparer._normalize_name(
                  connection.execute(
                          'SELECT CURRENT_SCHEMA FROM DUAL').scalar())
  
      def has_table(self, connection, table_name, schema=None):
          denormalize = self.identifier_preparer._denormalize_name
          bind = [denormalize(table_name)]
          if schema is None:
              sql = ("SELECT tablename FROM TABLES "
                     "WHERE TABLES.TABLENAME=? AND"
                     "  TABLES.SCHEMANAME=CURRENT_SCHEMA ")
          else:
              sql = ("SELECT tablename FROM TABLES "
                     "WHERE TABLES.TABLENAME = ? AND"
                     "  TABLES.SCHEMANAME=? ")
              bind.append(denormalize(schema))
  
          rp = connection.execute(sql, bind)
          return bool(rp.first())
  
      @reflection.cache
      def get_table_names(self, connection, schema=None, **kw):
          if schema is None:
              sql = (" SELECT TABLENAME FROM TABLES WHERE "
                     " SCHEMANAME=CURRENT_SCHEMA ")
              rs = connection.execute(sql)
          else:
              sql = (" SELECT TABLENAME FROM TABLES WHERE "
                     " SCHEMANAME=? ")
              matchname = self.identifier_preparer._denormalize_name(schema)
              rs = connection.execute(sql, matchname)
          normalize = self.identifier_preparer._normalize_name
          return [normalize(row[0]) for row in rs]
  
      def reflecttable(self, connection, table, include_columns):
          denormalize = self.identifier_preparer._denormalize_name
          normalize = self.identifier_preparer._normalize_name
  
          st = ('SELECT COLUMNNAME, MODE, DATATYPE, CODETYPE, LEN, DEC, '
                '  NULLABLE, "DEFAULT", DEFAULTFUNCTION '
                'FROM COLUMNS '
                'WHERE TABLENAME=? AND SCHEMANAME=%s '
                'ORDER BY POS')
  
          fk = ('SELECT COLUMNNAME, FKEYNAME, '
                '  REFSCHEMANAME, REFTABLENAME, REFCOLUMNNAME, RULE, '
                '  (CASE WHEN REFSCHEMANAME = CURRENT_SCHEMA '
                '   THEN 1 ELSE 0 END) AS in_schema '
                'FROM FOREIGNKEYCOLUMNS '
                'WHERE TABLENAME=? AND SCHEMANAME=%s '
                'ORDER BY FKEYNAME ')
  
          params = [denormalize(table.name)]
          if not table.schema:
              st = st % 'CURRENT_SCHEMA'
              fk = fk % 'CURRENT_SCHEMA'
          else:
              st = st % '?'
              fk = fk % '?'
              params.append(denormalize(table.schema))
  
          rows = connection.execute(st, params).fetchall()
          if not rows:
              raise exc.NoSuchTableError(table.fullname)
  
          include_columns = set(include_columns or [])
  
          for row in rows:
              (name, mode, col_type, encoding, length, scale,
               nullable, constant_def, func_def) = row
  
              name = normalize(name)
  
              if include_columns and name not in include_columns:
                  continue
  
              type_args, type_kw = [], {}
              if col_type == 'FIXED':
                  type_args = length, scale
                  # Convert FIXED(10) DEFAULT SERIAL to our Integer
                  if (scale == 0 and
                      func_def is not None and func_def.startswith('SERIAL')):
                      col_type = 'INTEGER'
                      type_args = length,
              elif col_type in 'FLOAT':
                  type_args = length,
              elif col_type in ('CHAR', 'VARCHAR'):
                  type_args = length,
                  type_kw['encoding'] = encoding
              elif col_type == 'LONG':
                  type_kw['encoding'] = encoding
  
              try:
                  type_cls = ischema_names[col_type.lower()]
                  type_instance = type_cls(*type_args, **type_kw)
              except KeyError:
                  util.warn("Did not recognize type '%s' of column '%s'" %
                            (col_type, name))
                  type_instance = sqltypes.NullType
  
              col_kw = {'autoincrement': False}
              col_kw['nullable'] = (nullable == 'YES')
              col_kw['primary_key'] = (mode == 'KEY')
  
              if func_def is not None:
                  if func_def.startswith('SERIAL'):
                      if col_kw['primary_key']:
                          # No special default- let the standard autoincrement
                          # support handle SERIAL pk columns.
                          col_kw['autoincrement'] = True
                      else:
                          # strip current numbering
                          col_kw['server_default'] = schema.DefaultClause(
                              sql.text('SERIAL'))
                          col_kw['autoincrement'] = True
                  else:
                      col_kw['server_default'] = schema.DefaultClause(
                          sql.text(func_def))
              elif constant_def is not None:
                  col_kw['server_default'] = schema.DefaultClause(sql.text(
                      "'%s'" % constant_def.replace("'", "''")))
  
              table.append_column(schema.Column(name, type_instance, **col_kw))
  
          fk_sets = itertools.groupby(connection.execute(fk, params),
                                      lambda row: row.FKEYNAME)
          for fkeyname, fkey in fk_sets:
              fkey = list(fkey)
              if include_columns:
                  key_cols = set([r.COLUMNNAME for r in fkey])
                  if key_cols != include_columns:
                      continue
  
              columns, referants = [], []
              quote = self.identifier_preparer._maybe_quote_identifier
  
              for row in fkey:
                  columns.append(normalize(row.COLUMNNAME))
                  if table.schema or not row.in_schema:
                      referants.append('.'.join(
                          [quote(normalize(row[c]))
                           for c in ('REFSCHEMANAME', 'REFTABLENAME',
                                     'REFCOLUMNNAME')]))
                  else:
                      referants.append('.'.join(
                          [quote(normalize(row[c]))
                           for c in ('REFTABLENAME', 'REFCOLUMNNAME')]))
  
              constraint_kw = {'name': fkeyname.lower()}
              if fkey[0].RULE is not None:
                  rule = fkey[0].RULE
                  if rule.startswith('DELETE '):
                      rule = rule[7:]
                  constraint_kw['ondelete'] = rule
  
              table_kw = {}
              if table.schema or not row.in_schema:
                  table_kw['schema'] = normalize(fkey[0].REFSCHEMANAME)
  
              ref_key = schema._get_table_key(normalize(fkey[0].REFTABLENAME),
                                              table_kw.get('schema'))
              if ref_key not in table.metadata.tables:
                  schema.Table(normalize(fkey[0].REFTABLENAME),
                               table.metadata,
                               autoload=True, autoload_with=connection,
                               **table_kw)
  
              constraint = schema.ForeignKeyConstraint(
                              columns, referants, link_to_name=True,
                              **constraint_kw)
              table.append_constraint(constraint)
  
      def has_sequence(self, connection, name):
          # [ticket:726] makes this schema-aware.
          denormalize = self.identifier_preparer._denormalize_name
          sql = ("SELECT sequence_name FROM SEQUENCES "
                 "WHERE SEQUENCE_NAME=? ")
  
          rp = connection.execute(sql, denormalize(name))
          return bool(rp.first())
  
  
  def _autoserial_column(table):
      """Finds the effective DEFAULT SERIAL column of a Table, if any."""
  
      for index, col in enumerate(table.primary_key.columns):
          if (isinstance(col.type, (sqltypes.Integer, sqltypes.Numeric)) and
              col.autoincrement):
              if isinstance(col.default, schema.Sequence):
                  if col.default.optional:
                      return index, col
              elif (col.default is None or
                    (not isinstance(col.server_default, schema.DefaultClause))):
                  return index, col
  
      return None, None
  
  