module ActiveRecord::ConnectionAdapters::DatabaseLimits

def column_name_length

the maximum length of a column name 
def column_name_length
  64
end

def columns_per_multicolumn_index

the maximum number of columns in a multicolumn index 
def columns_per_multicolumn_index
  16
end

def columns_per_table

the maximum number of columns per table 
def columns_per_table
  1024
end

def in_clause_length

the maximum number of elements in an IN (x,y,z) clause 
def in_clause_length
  65535
end

def index_name_length

the maximum length of an index name 
def index_name_length
  64
end

def indexes_per_table

the maximum number of indexes per table 
def indexes_per_table
  16
end

def joins_per_query

maximum number of joins in a single query 
def joins_per_query
  256
end

def sql_query_length

the maximum length of a SQL query 
def sql_query_length
  1048575
end

def table_alias_length

the maximum length of a table alias 
def table_alias_length
  255
end

def table_name_length

the maximum length of a table name 
def table_name_length
  64
end