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#ifndef SQL_JOIN_OPTIMIZER_JOIN_DERIVED_KEYS_H
#define SQL_JOIN_OPTIMIZER_JOIN_DERIVED_KEYS_H

class JOIN;
class Query_block;
class THD;
struct AccessPath;

/**
   Collect the set fields of derived tables that are present in predicates
   like "derived_tab.field=function(other_tab.field)". Generate keys for every
   derived_tab+other_tab pair in that set.
   @param thd The current thread.
   @param join The current join.
*/
bool MakeDerivedKeys(THD *thd, JOIN *join);

/**
   Remove any unused keys on derived tables. Update the key number in any
   AccessPath that uses a key that gets shifted to a lower number due to
   those removals.
   @param thd The current thread.
   @param query_block The current Query_block.
   @param root_path The root path of 'query_block'.
*/
void FinalizeDerivedKeys(THD *thd, const Query_block &query_block,
                         AccessPath *root_path);

#endif
