sql_constraint.h

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/* Copyright (c) 2019, 2023, Oracle and/or its affiliates.
 
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   it under the terms of the GNU General Public License, version 2.0,
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef SQL_CONSTRAINT_INCLUDED
#define SQL_CONSTRAINT_INCLUDED
 
#include "my_inttypes.h"  // ulonglong
 
class Alter_constraint_enforcement;
class Alter_drop;
class Alter_info;
class KEY;
struct TABLE;
class THD;
namespace dd {
class Table;
}
 
/**
  Base class to resolve constraints type for the constraints specified in the
  ALTER TABLE ... DROP/ALTER CONSTRAINT operation.
 
  For a constraint specified in the DROP/ALTER CONSTRAINT operations of a ALTER
  TABLE statement, actual constraint type is unknown. This is the class to
  resolve the actual constraint type (PRIMARY, UNIQUE, FOREIGN KEY or CHECK) of
  a constraint by name. Changes to Alter_info instance are reverted in the
  destructor to make operation safe for re-execution of a stored routines and
  prepared statements.
*/
class Constraint_type_resolver {
 public:
  explicit Constraint_type_resolver(Alter_info *alter_info)
      : m_alter_info(alter_info) {}
  virtual ~Constraint_type_resolver() = default;
 
  /**
    Method to check if constraint type resolution is needed.
 
    @retval true  if ALTER TABLE statement has DROP/ALTER CONSTRAINT operations.
    @retval false Otherwise.
  */
  virtual bool is_type_resolution_needed() const = 0;
 
  /**
    Method to resolve constraints type.
 
    @param            thd                      Thread handle.
    @param            src_table                TABLE instance of a source table.
    @param            dd_src_table             Data-dictionary table instance of
                                               a source table.
 
    @retval           false                    Success.
    @retval           true                     Failure.
  */
  virtual bool resolve_constraints_type(THD *thd, const TABLE *src_table,
                                        const dd::Table *dd_src_table) = 0;
 
 protected:
  /**
    Helper method to check if "name" type is PRIMARY or UNIQUE constraint.
 
    @param  src_table      TABLE instance of a source table.
    @param  name           Constraint name.
 
    @retval  non-nullptr   Returns pointer to KEY instance if "name" is PRIMARY
                           or UNIQUE constraint.
    @retval  nullptr       Otherwise.
  */
  KEY *is_primary_or_unique_constraint(const TABLE *src_table,
                                       const char *name);
 
  /**
    Helper method to check if "name" type is REFERENTIAL constraint.
 
    @param  dd_src_table   Data-dictionary table instance of a source table.
    @param  name           Constraint name.
 
    @retval true           If "name" type is REFERENTIAL.
    @retval false          Otherwise.
  */
  bool is_referential_constraint(const dd::Table *dd_src_table,
                                 const char *name);
 
  /**
    Helper method to check if "name" type is CHECK constraint.
 
    @param  src_table      TABLE instance of a source table.
    @param  name           Constraint name.
 
    @retval true           If "name" type is CHECK.
    @retval false          Otherwise.
  */
  bool is_check_constraint(const TABLE *src_table, const char *name);
 
 protected:
  /// Alter_info instance describing table being altered.
  Alter_info *m_alter_info;
};
 
/**
  Class to resolve constraints type for the constraints specified in the
  ALTER TABLE ... DROP CONSTRAINT operation.
 
  For a constraint specified in the DROP CONSTRAINT operations of a ALTER TABLE
  statement, actual constraint type is unknown. This is the class to resolve
  actual constraint type (PRIMARY, UNIQUE, FOREIGN KEY or CHECK) by constraint
  name. Alter_drop elements with actual constraint type are added to the
  Alter_info::Alter_drop list. To make changes safe for re-execution of a stored
  routines and prepared statements, elements added to Alter_drop list are
  removed in the destructor.
*/
class Drop_constraint_type_resolver final : public Constraint_type_resolver {
 public:
  explicit Drop_constraint_type_resolver(Alter_info *alter_info)
      : Constraint_type_resolver(alter_info) {}
  ~Drop_constraint_type_resolver() override;
 
  /**
    Method to check if constraint type resolution is needed.
 
    @retval true  if ALTER TABLE statement has DROP CONSTRAINT operations.
    @retval false Otherwise.
  */
  bool is_type_resolution_needed() const override;
 
  /**
    Method to resolve constraints type.
 
    @param            thd                      Thread handle.
    @param            src_table                TABLE instance of a source table.
    @param            dd_src_table             Data-dictionary table instance of
                                               a source table.
 
    @retval           false                    Success.
    @retval           true                     Failure.
  */
  bool resolve_constraints_type(THD *thd, const TABLE *src_table,
                                const dd::Table *dd_src_table) override;
 
 private:
  /**
    Method to resolve constraint type.
 
    @param            thd                      Thread handle.
    @param            src_table                TABLE instance of a source table.
    @param            dd_src_table             Data-dictionary table instance of
                                               a source table.
    @param            drop                     Alter_drop instance for which
                                               type should be resolved.
 
    @retval           false                    Success.
    @retval           true                     Failure.
  */
  bool resolve_constraint_type(THD *thd, const TABLE *src_table,
                               const dd::Table *dd_src_table,
                               const Alter_drop *drop);
 
 private:
  /// Flags set in Alter_info::flags while fixing type for constraint.
  ulonglong m_flags{0};
 
  /*
    Alter_drop element with actual type is added to the Alter_info::drop_list
    for each DROP CONSTRAINT operation. Member holds the position of the first
    Alter_drop element with actual type in the Alter_info::drop_list list.
  */
  uint m_first_fixed_alter_drop_pos{0};
};
 
/**
  Class to resolve constraints type for the constraints specified in the
  ALTER TABLE ... ALTER CONSTRAINT operation.
 
  For a constraint specified in the ALTER CONSTRAINT operations of a ALTER TABLE
  statement, actual constraint type is unknown. This is the class to resolve
  actual constraint type (PRIMARY, UNIQUE, FOREIGN KEY or CHECK) by constraint
  name. Alter_constraint_enforcement elements with actual constraint type are
  added to the alter_constraint_enforcement_list. To make changes safe for
  re-execution of stored routines and prepared statements, elements added to
  list are removed in the destructor.
*/
class Enforce_constraint_type_resolver final : public Constraint_type_resolver {
 public:
  explicit Enforce_constraint_type_resolver(Alter_info *alter_info)
      : Constraint_type_resolver(alter_info) {}
  ~Enforce_constraint_type_resolver() override;
 
  /**
    Method to check if constraint type resolution is needed.
 
    @retval true  if ALTER TABLE statement has ALTER CONSTRAINT operations.
    @retval false Otherwise.
  */
  bool is_type_resolution_needed() const override;
 
  /**
    Method to resolve constraints type.
 
    @param            thd                      Thread handle.
    @param            src_table                TABLE instance of a source table.
    @param            dd_src_table             Data-dictionary table instance of
                                               a source table.
 
    @retval           false                    Success.
    @retval           true                     Failure.
  */
  bool resolve_constraints_type(THD *thd, const TABLE *src_table,
                                const dd::Table *dd_src_table) override;
 
 private:
  /**
    Method to resolve constraint type.
 
    @param            thd                      Thread handle.
    @param            src_table                TABLE instance of a source table.
    @param            dd_src_table             Data-dictionary table instance of
                                               a source table.
    @param            alter_constraint         Alter_constraint_enforcement
                                               instance for which type should be
                                               resolved.
 
    @retval           false                    Success.
    @retval           true                     Failure.
  */
  bool resolve_constraint_type(
      THD *thd, const TABLE *src_table, const dd::Table *dd_src_table,
      const Alter_constraint_enforcement *alter_constraint);
 
 private:
  /// Flags set in Alter_info::flags while fixing type for check constraint.
  ulonglong m_flags{0};
 
  /*
    Alter_constraint_enforcement element with actual type is added to the
    Alter_info::alter_constraint_enforcement_list for each ALTER CONSTRAINT
    operation. Member holds position of the first Alter_constraint_enforcement
    element with actual type in the alter_constraint_enforcement_list.
  */
  uint m_first_fixed_alter_constraint_pos{0};
};
#endif  // SQL_CONSTRAINT_INCLUDED