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112 lines
3.1 KiB
Ruby
112 lines
3.1 KiB
Ruby
module Arel
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module Visitors
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class Oracle < Arel::Visitors::ToSql
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private
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def visit_Arel_Nodes_SelectStatement o
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o = order_hacks(o)
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# if need to select first records without ORDER BY and GROUP BY and without DISTINCT
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# then can use simple ROWNUM in WHERE clause
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if o.limit && o.orders.empty? && !o.offset && o.cores.first.projections.first !~ /^DISTINCT /
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o.cores.last.wheres.push Nodes::LessThanOrEqual.new(
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Nodes::SqlLiteral.new('ROWNUM'), o.limit
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)
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o.limit = nil
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return super
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end
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if o.limit && o.offset
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o = o.dup
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limit = o.limit.to_i
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offset = o.offset
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o.limit = nil
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o.offset = nil
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sql = super(o)
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return <<-eosql
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SELECT * FROM (
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SELECT raw_sql_.*, rownum raw_rnum_
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FROM (#{sql}) raw_sql_
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WHERE rownum <= #{offset.expr.to_i + limit}
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)
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WHERE #{visit offset}
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eosql
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end
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if o.limit
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o = o.dup
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limit = o.limit
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o.limit = nil
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return "SELECT * FROM (#{super(o)}) WHERE ROWNUM <= #{limit}"
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end
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if o.offset
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o = o.dup
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offset = o.offset
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o.offset = nil
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sql = super(o)
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return <<-eosql
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SELECT * FROM (
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SELECT raw_sql_.*, rownum raw_rnum_
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FROM (#{sql}) raw_sql_
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)
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WHERE #{visit offset}
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eosql
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end
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super
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end
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def visit_Arel_Nodes_Offset o
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"raw_rnum_ > #{visit o.expr}"
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end
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###
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# Hacks for the order clauses specific to Oracle
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def order_hacks o
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return o if o.orders.empty?
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return o unless o.cores.any? do |core|
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core.projections.any? do |projection|
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/DISTINCT.*FIRST_VALUE/ === projection
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end
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end
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# Previous version with join and split broke ORDER BY clause
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# if it contained functions with several arguments (separated by ',').
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#
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# orders = o.orders.map { |x| visit x }.join(', ').split(',')
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orders = o.orders.map do |x|
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string = visit x
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if string.include?(',')
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split_order_string(string)
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else
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string
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end
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end.flatten
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o.orders = []
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orders.each_with_index do |order, i|
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o.orders <<
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Nodes::SqlLiteral.new("alias_#{i}__#{' DESC' if /\bdesc$/i === order}")
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end
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o
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end
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# Split string by commas but count opening and closing brackets
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# and ignore commas inside brackets.
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def split_order_string(string)
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array = []
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i = 0
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string.split(',').each do |part|
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if array[i]
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array[i] << ',' << part
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else
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# to ensure that array[i] will be String and not Arel::Nodes::SqlLiteral
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array[i] = '' << part
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end
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i += 1 if array[i].count('(') == array[i].count(')')
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end
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array
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end
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end
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end
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end
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