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|
module Groonga
module Sharding
class LogicalSelectCommand < Command
register("logical_select",
[
"logical_table",
"shard_key",
"min",
"min_border",
"max",
"max_border",
"filter",
"sortby",
"output_columns",
"offset",
"limit",
"drilldown",
"drilldown_sortby",
"drilldown_output_columns",
"drilldown_offset",
"drilldown_limit",
])
def run_body(input)
enumerator = LogicalEnumerator.new("logical_select", input)
context = ExecuteContext.new(input)
begin
executor = Executor.new(context)
executor.execute
n_results = 1
drilldowns = context.drilldown.result_sets
n_results += drilldowns.size
writer.array("RESULT", n_results) do
write_records(writer, context)
write_drilldowns(writer, context, drilldowns)
end
ensure
context.close
end
end
private
def write_records(writer, context)
result_sets = context.result_sets
n_hits = 0
n_elements = 2 # for N hits and columns
result_sets.each do |result_set|
n_hits += result_set.size
n_elements += result_set.size
end
output_columns = context.output_columns
writer.array("RESULTSET", n_elements) do
writer.array("NHITS", 1) do
writer.write(n_hits)
end
first_result_set = result_sets.first
if first_result_set
writer.write_table_columns(first_result_set, output_columns)
end
current_offset = context.offset
current_offset += n_hits if current_offset < 0
current_limit = context.limit
current_limit += n_hits + 1 if current_limit < 0
options = {
:offset => current_offset,
:limit => current_limit,
}
result_sets.each do |result_set|
if result_set.size > current_offset
writer.write_table_records(result_set, output_columns, options)
end
if current_offset > 0
current_offset = [current_offset - result_set.size, 0].max
end
current_limit -= result_set.size
break if current_limit <= 0
options[:offset] = current_offset
options[:limit] = current_limit
end
end
end
def write_drilldowns(writer, context, drilldowns)
output_columns = context.drilldown.output_columns
options = {
:offset => context.drilldown.output_offset,
:limit => context.drilldown.limit,
}
drilldowns.each do |drilldown|
n_elements = 2 # for N hits and columns
n_elements += drilldown.size
writer.array("RESULTSET", n_elements) do
writer.array("NHITS", 1) do
writer.write(drilldown.size)
end
writer.write_table_columns(drilldown, output_columns)
writer.write_table_records(drilldown, output_columns,
options)
end
end
end
module KeysParsable
private
def parse_keys(raw_keys)
return [] if raw_keys.nil?
raw_keys.strip.split(/ *, */)
end
end
class ExecuteContext
include KeysParsable
attr_reader :enumerator
attr_reader :filter
attr_reader :offset
attr_reader :limit
attr_reader :sort_keys
attr_reader :output_columns
attr_reader :result_sets
attr_reader :drilldown
def initialize(input)
@input = input
@enumerator = LogicalEnumerator.new("logical_select", @input)
@filter = @input[:filter]
@offset = (@input[:offset] || 0).to_i
@limit = (@input[:limit] || 10).to_i
@sort_keys = parse_keys(@input[:sortby])
@output_columns = @input[:output_columns] || "_key, *"
@result_sets = []
@drilldown = DrilldownExecuteContext.new(@input)
end
def close
@result_sets.each do |result_set|
result_set.close if result_set.temporary?
end
@drilldown.close
end
end
class DrilldownExecuteContext
include KeysParsable
attr_reader :keys
attr_reader :offset
attr_reader :limit
attr_reader :sort_keys
attr_reader :output_columns
attr_reader :output_offset
attr_reader :result_sets
attr_reader :unsorted_result_sets
def initialize(input)
@input = input
@keys = parse_keys(@input[:drilldown])
@offset = (@input[:drilldown_offset] || 0).to_i
@limit = (@input[:drilldown_limit] || 10).to_i
@sort_keys = parse_keys(@input[:drilldown_sortby])
@output_columns = @input[:drilldown_output_columns]
@output_columns ||= "_key, _nsubrecs"
if @sort_keys.empty?
@output_offset = @offset
else
@output_offset = 0
end
@result_sets = []
@unsorted_result_sets = []
end
def close
@result_sets.each do |result_set|
result_set.close
end
@unsorted_result_sets.each do |result_set|
result_set.close
end
end
end
class Executor
def initialize(context)
@context = context
end
def execute
execute_search
execute_drilldown
end
private
def execute_search
first_table = nil
enumerator = @context.enumerator
enumerator.each do |table, shard_key, shard_range|
first_table ||= table
next if table.empty?
shard_executor = ShardExecutor.new(@context,
table, shard_key, shard_range)
shard_executor.execute
end
if first_table.nil?
message =
"[logical_select] no shard exists: " +
"logical_table: <#{enumerator.logical_table}>: " +
"shard_key: <#{enumerator.shard_key_name}>"
raise InvalidArgument, message
end
if @context.result_sets.empty?
result_set = HashTable.create(:flags => ObjectFlags::WITH_SUBREC,
:key_type => first_table)
@context.result_sets << result_set
end
end
def execute_drilldown
drilldown = @context.drilldown
group_result = TableGroupResult.new
sort_options = {
:offset => drilldown.offset,
:limit => drilldown.limit,
}
begin
group_result.key_begin = 0
group_result.key_end = 0
group_result.limit = 1
group_result.flags = TableGroupFlags::CALC_COUNT
drilldown.keys.each do |key|
@context.result_sets.each do |result_set|
result_set.group([key], group_result)
end
result_set = group_result.table
if drilldown.sort_keys.empty?
drilldown.result_sets << result_set
else
drilldown.result_sets << result_set.sort(drilldown.sort_keys,
sort_options)
drilldown.unsorted_result_sets << result_set
end
group_result.table = nil
end
ensure
group_result.close
end
end
end
class ShardExecutor
def initialize(context, table, shard_key, shard_range)
@context = context
@table = table
@shard_key = shard_key
@shard_range = shard_range
@filter = @context.filter
@result_sets = @context.result_sets
@target_range = @context.enumerator.target_range
@cover_type = @target_range.cover_type(@shard_range)
@expression_builder = RangeExpressionBuilder.new(@shard_key,
@target_range,
@filter)
end
def execute
return if @cover_type == :none
case @cover_type
when :all
filter_shard_all
when :partial_min
filter_table do |expression|
@expression_builder.build_partial_min(expression)
end
when :partial_max
filter_table do |expression|
@expression_builder.build_partial_max(expression)
end
when :partial_min_and_max
filter_table do |expression|
@expression_builder.build_partial_min_and_max(expression)
end
end
end
private
def filter_shard_all
if @filter.nil?
@result_sets << @table
else
filter_table do |expression|
@expression_builder.build_all(expression)
end
end
end
def create_expression(table)
expression = Expression.create(table)
begin
yield(expression)
ensure
expression.close
end
end
def filter_table
create_expression(@table) do |expression|
yield(expression)
@result_sets << @table.select(expression)
end
end
end
end
end
end
|