*** a/src/include/utils/rel.h
--- b/src/include/utils/rel.h
***************
*** 187,193 **** typedef struct RelationData
   * be applied to relations that use this format or a superset for
   * private options data.
   */
!  /* autovacuum-related reloptions. */
  typedef struct AutoVacOpts
  {
  	bool		enabled;
--- 187,203 ----
   * be applied to relations that use this format or a superset for
   * private options data.
   */
!  /*
!   * autovacuum-related reloptions.
!   *
!   * In 9.3 starting from 9.3.3 we use a different struct definition,
!   * accomodating security_barrier inside the autovacuum struct, so that new
!   * fields could be added at the end.  This is so that third-party modules
!   * compiled with the original definition of the struct can continue to
!   * access the security_barrier field in its original physical location,
!   * avoiding an ABI break.  (9.4 and up use the normal definition, where
!   * security_barrier is placed outside autovacuum options.)
!   */
  typedef struct AutoVacOpts
  {
  	bool		enabled;
***************
*** 200,213 **** typedef struct AutoVacOpts
  	int			freeze_table_age;
  	float8		vacuum_scale_factor;
  	float8		analyze_scale_factor;
  } AutoVacOpts;
  
  typedef struct StdRdOptions
  {
  	int32		vl_len_;		/* varlena header (do not touch directly!) */
  	int			fillfactor;		/* page fill factor in percent (0..100) */
! 	AutoVacOpts autovacuum;		/* autovacuum-related options */
! 	bool		security_barrier;		/* for views */
  } StdRdOptions;
  
  #define HEAP_MIN_FILLFACTOR			10
--- 210,226 ----
  	int			freeze_table_age;
  	float8		vacuum_scale_factor;
  	float8		analyze_scale_factor;
+ 	bool		security_barrier;
+ 	int			multixact_freeze_min_age;
+ 	int			multixact_freeze_max_age;
+ 	int			multixact_freeze_table_age;
  } AutoVacOpts;
  
  typedef struct StdRdOptions
  {
  	int32		vl_len_;		/* varlena header (do not touch directly!) */
  	int			fillfactor;		/* page fill factor in percent (0..100) */
! 	AutoVacOpts	autovacuum;		/* autovacuum -- includes security_barrier */
  } StdRdOptions;
  
  #define HEAP_MIN_FILLFACTOR			10
***************
*** 238,247 **** typedef struct StdRdOptions
  /*
   * RelationIsSecurityView
   *		Returns whether the relation is security view, or not
   */
  #define RelationIsSecurityView(relation)	\
  	((relation)->rd_options ?				\
! 	 ((StdRdOptions *) (relation)->rd_options)->security_barrier : false)
  
  /*
   * RelationIsValid
--- 251,264 ----
  /*
   * RelationIsSecurityView
   *		Returns whether the relation is security view, or not
+  *
+  * XXX this definition copes with unusual placement of the field to preserve
+  * ABI compatibility with releases prior to 9.3.3.
   */
  #define RelationIsSecurityView(relation)	\
  	((relation)->rd_options ?				\
! 	 ((StdRdOptions *) (relation)->rd_options)->autovacuum.security_barrier : \
! 	 false)
  
  /*
   * RelationIsValid