Oracle needs to override the behavior of distinct for the JDBC Adaptor
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Key: JRUBY-1344
URL: http://jira.codehaus.org/browse/JRUBY-1344
Project: JRuby
Issue Type: Bug
Components: ActiveRecord-JDBC
Affects Versions: JRuby 1.0.1
Reporter: Matthew Field
Assignee: Thomas E Enebo
Oracle cannot sort by columns that are not included in a query when there is a
distinct. It needs to use the FIRST_VALUE function on the ordered columns.
See the comment in the normal rails oracle adaptor for the distinct method. We
need to add something like the following.
def distinct(columns, order_by)
return "DISTINCT #{columns}" if order_by.blank?
# construct a valid DISTINCT clause, ie. one that includes the ORDER BY
columns, using
# FIRST_VALUE such that the inclusion of these columns doesn't invalidate the
DISTINCT
order_columns = order_by.split(',').map { |s| s.strip }.reject(&:blank?)
order_columns = order_columns.zip((0...order_columns.size).to_a).map do |c, i|
"FIRST_VALUE(#{c.split.first}) OVER (PARTITION BY #{columns} ORDER BY #{c})
AS alias_#{i}__"
end
sql = "DISTINCT #{columns}, "
sql << order_columns * ", "
end
# ORDER BY clause for the passed order option.
#
# Uses column aliases as defined by #distinct.
def add_order_by_for_association_limiting!(sql, options)
return sql if options[:order].blank?
order = options[:order].split(',').collect { |s| s.strip }.reject(&:blank?)
order.map! {|s| $1 if s =~ / (.*)/}
order = order.zip((0...order.size).to_a).map { |s,i| "alias_#{i}__ #{s}"
}.join(', ')
sql << "ORDER BY #{order}"
end
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