impala/tests/comparison/common.py

# Copyright (c) 2014 Cloudera, Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from collections import defaultdict
from copy import deepcopy

# The model related modules (types.py, query.py, etc) are interconnected by circular
# imports which causes problems for the python import system. This module is intended to
# be the first of the circular modules imported. To be importable, no direct references
# are made to the other modules from this modules namespace. Instead, other modules are
# lazyily imported using the following function. Keep in mind that python "globals" are
# module local, there is no such thing as a cross-module global.
__ALREADY_IMPORTED = False
def get_import(name):
  global __ALREADY_IMPORTED
  if not __ALREADY_IMPORTED:
    from tests.comparison.types import (
        Boolean,
        Char,
        DataType,
        Float,
        Int,
        JOINABLE_TYPES,
        Number,
        Timestamp)
    from tests.comparison.funcs import AggFunc, AnalyticFunc, Func
    from tests.comparison.query import InlineView, Subquery, WithClauseInlineView
    for key, value in locals().items():
      globals()[key] = value
    __ALREADY_IMPORTED = True
  return globals()[name]

class ValExpr(object):
  '''This is class that represents a generic expr that results in a scalar.'''

  @property
  def type(self):
    '''Returns the type that this expr evaluates to. The type may be Int or Char but
       never BigInt or String. Valid return value are the set defined in types.TYPES.
    '''
    return self.exact_type.get_generic_type()

  @property
  def exact_type(self):
    '''Return the actual type of the val expr. For example "type" could return Int and
       "exact_type" could return TinyInt.
    '''
    pass

  @property
  def base_type(self):
    '''Returns the lowest type in the type heirarchy that is not DataType. For non-
       numeric types, the return value will be the same is self.type. Numeric types
       will return Number whereas self.type may be Decimal, Int, or Float.
    '''
    return self.type.get_base_type()

  @property
  def is_func(self):
    '''Evaluates to True if this expr is an instance of a function.'''
    return isinstance(self, get_import('Func'))

  @property
  def is_agg(self):
    '''Evaluates to True if this expr is an instance of an aggregate function.'''
    return isinstance(self, get_import('AggFunc'))

  @property
  def is_analytic(self):
    '''Evaluates to True if this expr is an instance of an analytic function.'''
    return isinstance(self, get_import('AnalyticFunc'))

  @property
  def contains_agg(self):
    '''Evaluates to True if this expression is an aggregate function or contains an
       aggregate function.
    '''
    if self.is_agg:
      return True
    return any(isinstance(arg, ValExpr) and arg.contains_agg for arg in self.args)

  @property
  def contains_analytic(self):
    '''Evaluates to True if this expression is an analytic function or contains an
       analytic function.
    '''
    if self.is_analytic:
      return True
    if self.is_func:
      for arg in self.args:
        if isinstance(arg, ValExpr) and arg.contains_analytic:
          return True

  @property
  def contains_subquery(self):
    '''Evaluates to True if this expression is a subquery or contains a subquery.'''
    if self.is_subquery:
      return True
    if self.is_func:
      for arg in self.args:
        if isinstance(arg, ValExpr) and arg.contains_subquery:
          return True

  @property
  def is_col(self):
    return isinstance(self, Column)

  @property
  def is_constant(self):
    return isinstance(self, get_import('DataType'))

  @property
  def is_subquery(self):
    return isinstance(self, get_import('Subquery'))

  @property
  def returns_boolean(self):
    return issubclass(self.type, get_import('Boolean'))

  @property
  def returns_int(self):
    return issubclass(self.type, get_import('Int'))

  @property
  def returns_float(self):
    return issubclass(self.type, get_import('Float'))

  @property
  def returns_char(self):
    return issubclass(self.type, get_import('Char'))

  @property
  def returns_timestamp(self):
    return issubclass(self.type, get_import('Timestamp'))

  def iter_exprs(self, filter=None):
    '''Return an iterator over all exprs that this expr contains as a function argument
       including this expr itself.
    '''
    if not filter or filter(self):
      yield self

  def count_col_refs(self):
    '''Return a dict with Columns as keys and the number of times the column was used
       in this expr as values.
    '''
    col_ref_counts = defaultdict(int)
    if self.is_func:
      for arg in self.args:
        if isinstance(arg, ValExpr):
          for col, count in arg.count_col_refs().iteritems():
            col_ref_counts[col] += count
    elif self.is_col:
      col_ref_counts[self] += 1
    return col_ref_counts


class Column(ValExpr):
  '''A representation of a column. All TableExprs will have Columns. So a Column
     may belong to an InlineView as well as a standard Table.

     This class is used in two ways:

       1) As a piece of metadata in a table definiton. In this usage the col isn't
          intended to represent an val.

       2) As an expr in a query, for example an item being selected or as part of
          a JOIN condition. In this usage the col is more like a val, which is why
          it implements/extends ValExpr.

  '''

  def __init__(self, owner, name, exact_type):
    self.owner = owner
    self.name = name
    self._exact_type = exact_type

  @property
  def exact_type(self):
    return self._exact_type

  @exact_type.setter
  def exact_type(self, exact_type):
    self._exact_type = exact_type

  def __hash__(self):
    return hash(self.name)

  def __eq__(self, other):
    if not isinstance(other, Column):
      return False
    if self is other:
      return True
    return self.name == other.name and self.owner.identifier == other.owner.identifier

  def __repr__(self):
    return '%s<name: %s, type: %s>' % (
        type(self).__name__, self.name, self.type.__name__)

  def __deepcopy__(self, memo):
    # Don't return a deep copy of owner, since that is a circular reference
    return Column(self.owner, self.name, self.exact_type)


class ValExprList(list):
  '''A list of ValExprs'''

  @property
  def by_type(self):
    return get_import('DataType').group_by_type(self)


class TableExpr(object):
  '''This class represents something that a query may use to SELECT from or JOIN on.'''

  def identifier(self):
    '''Returns either a table name or alias if one has been declared.'''
    pass

  def cols(self):
    pass

  @property
  def unique_cols(self):
    '''Returns a list of lists of Cols that in combination define a unique set of values
       within the table. The returned list could be thought of as a list of uniqueness
       constraints (though there may be no actual constraints or any other type of
       enforcement).
    '''
    return ValExprList()

  @property
  def joinable_cols(self):
    '''Returns a list of Cols that are of a type that is allowed in a JOIN. This is
       mostly an Impala specific thing since Impala requires at least one equality based
       join and not all types are allowed in equality comparisons. Also Boolean is
       excluded because of low cardinality.
    '''
    joinable_types = tuple(get_import('JOINABLE_TYPES'))
    return ValExprList(col for col in self.cols if issubclass(col.type, joinable_types))

  @property
  def col_types(self):
    '''Returns a Set containing the various column types that this TableExpr contains.'''
    return set(self.cols_by_type)

  def is_visible(self):
    '''If False is returned, columns from this TableExpr may only be used in JOIN
       conditions. This is intended to be used to identify ANTI and SEMI joined table
       exprs.
    '''
    pass

  @property
  def cols_by_type(self):
    '''Group cols of the same type into lists and return a dict of the results.'''
    return get_import('DataType').group_by_type(self.cols)

  @property
  def joinable_cols_by_type(self):
    return get_import('DataType').group_by_type(self.joinable_cols)

  @property
  def is_table(self):
    return isinstance(self, Table)

  @property
  def is_inline_view(self):
    return isinstance(self, get_import('InlineView'))

  @property
  def is_with_clause_inline_view(self):
    return isinstance(self, get_import('WithClauseInlineView'))

  def __eq__(self, other):
    if not isinstance(other, type(self)):
      return False
    return self.identifier == other.identifier


class Table(TableExpr):
  '''Represents a standard database table.'''

  def __init__(self, name):
    self.name = name
    self._cols = ValExprList()
    self._unique_cols = ValExprList()
    self.alias = None
    self.is_visible = True   # tables used in SEMI or ANTI JOINs are invisible

  @property
  def identifier(self):
    return self.alias or self.name

  @property
  def cols(self):
    return self._cols

  @cols.setter
  def cols(self, cols):
    self._cols = cols

  @property
  def unique_cols(self):
    return self._unique_cols

  @unique_cols.setter
  def unique_cols(self, unique_cols):
    self._unique_cols = unique_cols

  def __repr__(self):
    return 'Table<name: %s, cols: %s>' \
        % (self.name, ', '.join([str(col) for col in self.cols]))

  def __deepcopy__(self, memo):
    other = Table(self.name)
    other.alias = self.alias
    other.is_visible = self.is_visible
    cols_by_name = dict()
    # Copy the cols and set their owner to the copy of the TableExpr
    for col in self._cols:
      col = deepcopy(col, memo)
      col.owner = other
      cols_by_name[col.name] = col
    other._cols = ValExprList(cols_by_name[col.name] for col in self._cols)
    other._unique_cols = ValExprList()
    for col_combo in self._unique_cols:
      other_col_combo = set()
      for col in col_combo:
        if col.name in cols_by_name:
          col = cols_by_name[col.name]
        else:
          col = deepcopy(col, memo)
          col.owner = other
        other_col_combo.add(col)
      other.unique_cols.append(other_col_combo)
    return other


class TableExprList(list):
  '''A list of TableExprs.'''

  @property
  def cols(self):
    '''Return a list of all the Columns containd in all the TableExprs.'''
    return ValExprList(col for table_expr in self for col in table_expr.cols)

  @property
  def joinable_cols_by_type(self):
    cols_by_type = defaultdict(ValExprList)
    for table_expr in self:
      for type_, cols in table_expr.joinable_cols_by_type.iteritems():
        cols_by_type[type_].extend(cols)
    return cols_by_type

  @property
  def cols_by_type(self):
    cols_by_type = defaultdict(ValExprList)
    for table_expr in self:
      for type_, cols in table_expr.cols_by_type.iteritems():
        cols_by_type[type_].extend(cols)
    return cols_by_type

  @property
  def col_types(self):
    return tuple(self.cols_by_type)

  @property
  def by_col_type(self):
    '''Return a dict with keys being column types and values being lists of TableExprs
       that have at least one Column of that type.
    '''
    table_exprs_by_type = defaultdict(TableExprList)
    for table_expr in self:
      for col_type in table_expr.col_types:
        table_exprs_by_type[col_type].append(table_expr)
    return table_exprs_by_type