The Internals of PostgreSQL中对于存储的描述http://www.interdb.jp/pg/pgsql01.html#_1.2.

每个表或索引都作为一个page数组存储于物理数据文件中（page大小默认为8k，编译时可以指定），单个的表数据文件中包含多个page页（默认单个表文件最大1G，超过1G后会新建同名+“.1”后缀的数据文件，依次累加，同样在编译时可以指定单个文件的最大值）。page页的结构如下图所示。

而对于page页中存储的行数据Tuple，其结构为下图所示。

相关数据结构

// class="lazy" data-src/include/storage/bufpage.h

typedef struct PageHeaderData
{
	
	PageXLogRecPtr pd_lsn;		
	uint16		pd_checksum;	
	uint16		pd_flags;		
	LocationIndex pd_lower;		
	LocationIndex pd_upper;		
	LocationIndex pd_special;	
	uint16		pd_pagesize_version;
	TransactionId pd_prune_xid; 
	ItemIdData	pd_linp[FLEXIBLE_ARRAY_MEMBER]; 
} PageHeaderData;

// class="lazy" data-src/include/storage/itemid.h

typedef struct ItemIdData
{
	unsigned	lp_off:15,		
				lp_flags:2,		
				lp_len:15;		
} ItemIdData;


#define LP_UNUSED		0		
#define LP_NORMAL		1		
#define LP_REDIRECT		2		
#define LP_DEAD			3		

// class="lazy" data-src/include/access/htup_details.h

struct HeapTupleHeaderData
{
	union
	{
		HeapTupleFields t_heap;
		DatumTupleFields t_datum;
	}			t_choice;

	ItemPointerData t_ctid;		

	

#define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK2 2
	uint16		t_infomask2;	

#define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK 3
	uint16		t_infomask;		

#define FIELDNO_HEAPTUPLEHEADERDATA_HOFF 4
	uint8		t_hoff;			

	

#define FIELDNO_HEAPTUPLEHEADERDATA_BITS 5
	bits8		t_bits[FLEXIBLE_ARRAY_MEMBER];	

	
};

// class="lazy" data-src/include/access/htup.h

typedef struct HeapTupleData
{
	uint32		t_len;			
	ItemPointerData t_self;		
	Oid			t_tableOid;		
#define FIELDNO_HEAPTUPLEDATA_DATA 3
	HeapTupleHeader t_data;		
} HeapTupleData;