/*
 * XXX: This one combined record type replaces existing
 * XLOG_HEAP2_PRUNE, XLOG_HEAP2_VACUUM, and XLOG_HEAP2_FREEZE_PAGE record types
 */

/*
 * This is what we need to know about page pruning and freezing, both during
 * VACUUM and during opportunistic pruning.
 *
 * If XLPH_HAS_REDIRECTIONS, XLHP_HAS_DEAD_ITEMS or XLHP_HAS_FREEZE_PLANS is
 * set, acquires a full cleanup lock. Otherwise an ordinary exclusive lock is
 * enough (VACUUM's second heap pass generates such records).
 *
 * The data for block reference 0 contains "sub-records" depending on which
 * of the XLPH_HAS_* flags are set. See xlhp_* struct definitions below.
 */
typedef struct xl_heap_prune
{
	TransactionId snapshotConflictHorizon;
	uint8		flags;
} xl_heap_prune;

#define		XLHP_IS_CATALOG_REL			0x01 /* to handle recovery conflict during logical
											  * decoding on standby */
#define		XLHP_HAS_REDIRECTIONS		0x02
#define		XLHP_HAS_DEAD_ITEMS			0x04
#define		XLHP_HAS_NOW_UNUSED_ITEMS	0x08
#define		XLHP_HAS_FREEZE_PLANS		0x10

#define SizeOfHeapPrune (offsetof(xl_heap_prune, flags) + sizeof(uint8))

/*
 * Sub-record contained in block reference 0 of a prune record if
 * XLHP_HAS_REDIRECTIONS is set
 */
typedef struct xl_heap_prune_redirections
{
	uint16		nitems;
	struct
	{
		OffsetNumber from;
		OffsetNumber to;
	}	items[FLEXIBLE_ARRAY_MEMBER];
} xl_heap_prune_redirections;

/*
 * Sub-record contained in block reference 0 of a prune record if
 * XLHP_HAS_DEAD_ITEMS is set
 */
typedef struct xlhp_dead_items
{
	uint16		nitems;
	OffsetNumber items[FLEXIBLE_ARRAY_MEMBER];
} xlhp_dead_items;

/*
 * Sub-record contained in block reference 0 of a prune record if
 * XLHP_HAS_NOW_UNUSED_ITEMS is set
 */
typedef struct xlhp_now_unused_items
{
	uint16		nitems;
	OffsetNumber items[FLEXIBLE_ARRAY_MEMBER];
} xlhp_now_unused_items;

/*
 * This struct represents a 'freeze plan', which describes how to freeze a
 * group of one or more heap tuples (appears in xlhp_freeze sub-record)
 */
#define		XLH_FREEZE_XVAC		0x02
#define		XLH_INVALID_XVAC	0x04

typedef struct xlhp_freeze_plan
{
	TransactionId xmax;
	uint16		t_infomask2;
	uint16		t_infomask;
	uint8		frzflags;

	/* Length of individual page offset numbers array for this plan */
	uint16		ntuples;
	OffsetNumber items[FLEXIBLE_ARRAY_MEMBER];
} xlhp_freeze_plan;

/*
 * This is what we need to know about a block being frozen during vacuum
 *
 * Backup block 0's data contains an array of xl_heap_freeze_plan structs
 * (with nplans elements), followed by one or more page offset number arrays.
 * Each such page offset number array corresponds to a single freeze plan
 * (REDO routine freezes corresponding heap tuples using freeze plan).
 */
typedef struct xlhp_freeze
{
	uint16		nplans;

	/* xlhp_freeze_plan structs follow */
} xlhp_freeze;