diff options
Diffstat (limited to 'lib/arel/engines/sql/compilers')
| -rw-r--r-- | lib/arel/engines/sql/compilers/oracle_compiler.rb | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/lib/arel/engines/sql/compilers/oracle_compiler.rb b/lib/arel/engines/sql/compilers/oracle_compiler.rb new file mode 100644 index 0000000000..1f6b82dd2f --- /dev/null +++ b/lib/arel/engines/sql/compilers/oracle_compiler.rb @@ -0,0 +1,101 @@ +module Arel + module SqlCompiler + class OracleCompiler < GenericCompiler + + def select_sql + where_clauses_array = where_clauses + if limit_or_offset = !taken.blank? || !skipped.blank? + # if need to select first records without ORDER BY and GROUP BY + # then can use simple ROWNUM in WHERE clause + if skipped.blank? && groupings.blank? && orders.blank? + where_clauses_array << "ROWNUM <= #{taken}" if !taken.blank? && skipped.blank? && groupings.blank? && orders.blank? + limit_or_offset = false + end + end + + # when limit or offset subquery is used then cannot use FOR UPDATE directly + # and need to construct separate subquery for primary key + if use_subquery_for_lock = limit_or_offset && !locked.blank? + primary_key = begin + engine.quote_column_name(table.name.classify.constantize.primary_key) + rescue NameError + engine.quote_column_name("id") + end + select_attributes_string = primary_key + else + select_attributes_string = select_clauses.join(', ') + end + + # OracleEnhanced adapter workaround when ORDER BY is used with columns not + # present in DISTINCT columns list + order_clauses_array = if select_attributes_string =~ /DISTINCT.*FIRST_VALUE/ && !orders.blank? + order = order_clauses.join(', ').split(',').map { |s| s.strip }.reject(&:blank?) + order = order.zip((0...order.size).to_a).map { |s,i| "alias_#{i}__ #{'DESC' if s =~ /\bdesc$/i}" } + else + order_clauses + end + + query = build_query \ + "SELECT #{select_attributes_string}", + "FROM #{from_clauses}", + (joins(self) unless joins(self).blank? ), + ("WHERE #{where_clauses_array.join(" AND ")}" unless where_clauses_array.blank? ), + ("GROUP BY #{group_clauses.join(', ')}" unless groupings.blank? ), + ("HAVING #{having_clauses.join(', ')}" unless havings.blank? ), + ("ORDER BY #{order_clauses_array.join(', ')}" unless order_clauses_array.blank? ) + + # Use existing method from oracle_enhanced adapter to implement limit and offset using subqueries + engine.add_limit_offset!(query, :limit => taken, :offset => skipped) if limit_or_offset + + if use_subquery_for_lock + build_query \ + "SELECT #{select_clauses.join(', ')}", + "FROM #{from_clauses}", + "WHERE #{primary_key} IN (#{query})", + "#{locked}" + elsif !locked.blank? + build_query query, "#{locked}" + else + query + end + end + + def delete_sql + where_clauses_array = wheres.collect(&:to_sql) + where_clauses_array << "ROWNUM <= #{taken}" unless taken.blank? + build_query \ + "DELETE", + "FROM #{table_sql}", + ("WHERE #{where_clauses_array.join(' AND ')}" unless where_clauses_array.blank? ) + end + + protected + + def build_update_conditions_sql + conditions = "" + where_clauses_array = wheres.collect(&:to_sql) + # if need to select first records without ORDER BY + # then can use simple ROWNUM in WHERE clause + if !taken.blank? && orders.blank? + where_clauses_array << "ROWNUM <= #{taken}" + end + conditions << " WHERE #{where_clauses_array.join(' AND ')}" unless where_clauses_array.blank? + unless taken.blank? + conditions = limited_update_conditions(conditions, taken) + end + conditions + end + + def limited_update_conditions(conditions, taken) + # need to add ORDER BY only if just taken ones should be updated + conditions << " ORDER BY #{order_clauses.join(', ')}" unless orders.blank? + quoted_primary_key = engine.quote_column_name(primary_key) + subquery = "SELECT #{quoted_primary_key} FROM #{engine.connection.quote_table_name table.name} #{conditions}" + # Use existing method from oracle_enhanced adapter to get taken records when ORDER BY is used + engine.add_limit_offset!(subquery, :limit => taken) unless orders.blank? + "WHERE #{quoted_primary_key} IN (#{subquery})" + end + + end + end +end |