pg

const (
	// Value representing an invalid LSN (used in error conditions)
	InvalidLSN = LSN(math.MaxUint64)

	// WALPageSize == PostgreSQL's Page Size.  Page Size == BLKSZ WALPageSize
	// defaults to 8KB.  The same value used in the WAL is used in the PostgreSQL
	// Heap.
	//
	// TODO(seanc@): pull this data from `SHOW wal_block_size`.
	WALPageSize = 8 * units.KiB

	HeapPageSize = WALPageSize

	// WALFileSize == PostgreSQL WAL File Size.
	// WALFileSize defaults to 16MB
	//
	// TODO(seanc@): pull this value from `SHOW wal_segment_size`
	WALFileSize = 16 * units.MiB

	// HeapMaxSegmentSize is the max size of a single file in a relation.
	//
	// TODO(seanc@): pull this value from pg_controldata(1)'s "Blocks per segment
	// of large relation" and multiply it by WALBlockSize
	HeapMaxSegmentSize = 1 * units.GiB

	WALFilesPerSegment uint64 = 0x100000000 / uint64(WALFileSize)
)