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module Groonga
class ScanInfoDataSizeEstimator
def initialize(data, table)
@data = data
@table = table
@table_size = @table.size
end
def estimate
search_index = @data.search_indexes.first
return @table_size if search_index.nil?
index_column = resolve_index_column(search_index.index_column)
return @table_size if index_column.nil?
size = nil
case @data.op
when Operator::MATCH,
Operator::FUZZY
size = estimate_match(index_column)
when Operator::REGEXP
size = estimate_regexp(index_column)
when Operator::EQUAL
size = estimate_equal(index_column)
when Operator::LESS,
Operator::LESS_EQUAL,
Operator::GREATER,
Operator::GREATER_EQUAL
size = estimate_range(index_column)
when Operator::PREFIX
size = estimate_prefix(index_column)
when Operator::CALL
size = estimate_call(index_column)
end
size || @table_size
end
private
def resolve_index_column(index_column)
while index_column.is_a?(Accessor)
index_info = index_column.find_index(@data.op)
return nil if index_info.nil?
break if index_info.index == index_column
index_column = index_info.index
end
index_column
end
def sampling_cursor_limit(n_terms)
limit = n_terms * 0.01
if limit < 10
10
elsif limit > 1000
1000
else
limit.to_i
end
end
def estimate_match(index_column)
index_column.estimate_size(:query => @data.query.value)
end
def estimate_regexp(index_column)
index_column.estimate_size(:query => @data.query.value,
:mode => @data.op)
end
def estimate_equal(index_column)
query = @data.query
if index_column.is_a?(Accessor)
table = index_column.object
if index_column.name == "_id"
if table.id?(query.value)
1
else
0
end
else
if table[query.value]
1
else
0
end
end
else
lexicon = index_column.lexicon
if query.domain == lexicon.id
term_id = query.value
else
term_id = lexicon[query]
end
return 0 if term_id.nil?
index_column.estimate_size(:term_id => term_id)
end
end
def estimate_range(index_column)
if index_column.is_a?(Table)
is_table_search = true
lexicon = index_column
elsif index_column.is_a?(Groonga::Accessor)
is_table_search = true
lexicon = index_column.object
else
is_table_search = false
lexicon = index_column.lexicon
end
n_terms = lexicon.size
return 0 if n_terms.zero?
value = @data.query.value
options = {
:limit => sampling_cursor_limit(n_terms),
}
case @data.op
when Operator::LESS
options[:max] = value
options[:flags] = TableCursorFlags::LT
when Operator::LESS_EQUAL
options[:max] = value
options[:flags] = TableCursorFlags::LE
when Operator::GREATER
options[:min] = value
options[:flags] = TableCursorFlags::GT
when Operator::GREATER_EQUAL
options[:min] = value
options[:flags] = TableCursorFlags::GE
end
TableCursor.open(lexicon, options) do |cursor|
if is_table_search
size = 1
else
size = index_column.estimate_size(:lexicon_cursor => cursor)
end
size += 1 if cursor.next != ID::NIL
size
end
end
def estimate_prefix(index_column)
is_table_search =
(index_column.is_a?(Accessor) and
index_column.name == "_key")
if is_table_search
lexicon = index_column.object
else
lexicon = index_column.lexicon
end
n_terms = lexicon.size
return 0 if n_terms.zero?
value = @data.query.value
options = {
:min => value,
:limit => sampling_cursor_limit(n_terms),
:flags => TableCursorFlags::PREFIX,
}
TableCursor.open(lexicon, options) do |cursor|
if is_table_search
size = 1
else
size = index_column.estimate_size(:lexicon_cursor => cursor)
end
size += 1 if cursor.next != ID::NIL
size
end
end
def estimate_call(index_column)
procedure = @data.args[0]
arguments = @data.args[1..-1].collect do |arg|
if arg.is_a?(::Groonga::Object)
ExpressionTree::Variable.new(arg)
else
ExpressionTree::Constant.new(arg)
end
end
node = ExpressionTree::FunctionCall.new(procedure, arguments)
node.estimate_size(@table)
end
end
end
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