Data merge method which reads first physical unit twice for respectively performing first stage programming operation and second stage programming operation on second physical unit, memory storage device and memory control circuit unit

1. A data merge method for a memory storage device comprising a plurality of physical units, the data merge method comprising:

performing a data merge operation to store valid data collected from a source node to a recycling node,

wherein the source node comprises at least one first physical unit among the physical units, the recycling node comprises a second physical unit among the physical units, and

the data merge operation comprises:

reading a first data from the at least one first physical unit by a first reading operation;

performing a first stage programming operation on the second physical unit according to the first data;

reading the first data from the at least one first physical unit again by a second reading operation after the first stage programming operation is performed; and

performing a second stage programming operation on the second physical unit according to the first data read by the second reading operation.

2. The data merge method of claim 1 , wherein the source node further comprises at least one third physical unit among the physical units, the recycling node further comprises a fourth physical unit among the physical units, and the data merge operation further comprises:

reading a second data from the at least one third physical unit; and

programming the fourth physical unit according to the second data between the first stage programming operation and the second stage programming operation.

3. The data merge method of claim 1 , wherein the data merge operation further comprises:

storing the first data read by the first reading operation into a buffer memory temporarily, so as to provide the first data used in the first stage programming operation;

storing a second data into the buffer memory temporarily, wherein at least part of the first data read by the first reading operation is overwritten by the second data in the buffer memory; and

storing the first data read by the second reading operation into the buffer memory temporarily, so as to provide the first data used in the second stage programming operation.

4. The data merge method of claim 1 , further comprising:

recording read information in a management table, wherein the read information reflects whether the at least one first physical unit is read by at least one of the first reading operation and the second reading operation; and

erasing the at least one first physical unit according to the read information.

5. The data merge method of claim 1 , wherein the second physical unit is programmed by the first stage programming operation and the second stage programming operation sequentially to store the first data.

6. The data merge method of claim 1 , wherein the first stage programming operation and the second stage programming operation belong to a multi stage programming operation, and at least three bits is stored in one memory cell of the second physical unit being programmed by the multi stage programming operation.

7. The data merge method of claim 1 , further comprising:

storing the first data read by the first reading operation or the second reading operation in a buffer memory temporarily,

wherein the second physical unit has a basic capacity, and an available capacity of the buffer memory is less than twice of the basic capacity.

8. A memory storage device, comprising:

a connection interface unit, configured to couple to a host system;

a rewritable non-volatile memory module which comprises a plurality of physical units; and

a memory control circuit unit, coupled to the connection interface unit and the rewritable non-volatile memory module,

wherein the memory control circuit unit is configured to perform a data merge operation to store valid data collected from a source node to a recycling node,

wherein the source node comprises at least one first physical unit among the physical units, the recycling node comprises a second physical unit among the physical units, and

the data merge operation comprises:

sending a first read command sequence which instructs a reading of a first data from the at least one first physical unit by a first reading operation;

sending a first write command sequence which instructs a first stage programming operation on the second physical unit according to the first data;

sending a second read command sequence which instructs a reading of the first data from the at least one first physical unit again by a second reading operation after the first stage programming operation is performed; and

sending a second write command sequence which instructs a second stage programming operation on the second physical unit according to the first data read by the second reading operation.

9. The memory storage device of claim 8 , wherein the source node further comprises at least one third physical unit among the physical units, the recycling node further comprises a fourth physical unit among the physical units, and the data merge operation further comprises:

sending a third read command sequence which instructs a reading of a second data from the at least one third physical unit; and

sending a third write command sequence which instructs a programming of the fourth physical unit according to the second data between the first stage programming operation and the second stage programming operation.

10. The memory storage device of claim 8 , wherein the data merge operation further comprises:

storing the first data read by the first reading operation into a buffer memory temporarily, so as to provide the first data used in the first stage programming operation;

storing a second data into the buffer memory temporarily, wherein at least part of the first data read by the first reading operation is overwritten by the second data in the buffer memory; and

storing the first data read by the second reading operation into the buffer memory temporarily, so as to provide the first data used in the second stage programming operation.

11. The memory storage device of claim 8 , wherein the memory control circuit unit is further configured to record read information in a management table and erase the at least one first physical unit according to the read information, and the read information reflects whether the at least one first physical unit is read by at least one of the first reading operation and the second reading operation.

12. The memory storage device of claim 8 , wherein the second physical unit is programmed by the first stage programming operation and the second stage programming operation sequentially to store the first data.

13. The memory storage device of claim 8 , wherein the first stage programming operation and the second stage programming operation belong to a multi stage programming operation, and at least three bits is stored in one memory cell of the second physical unit being programmed by the multi stage programming operation.

14. The memory storage device of claim 8 , wherein the memory control circuit unit is further configured to store the first data read by the first reading operation or the second reading operation in a buffer memory temporarily,

wherein the second physical unit has a basic capacity, and an available capacity of the buffer memory is less than twice of the basic capacity.

15. A memory control circuit unit for controlling a rewritable non-volatile memory module which comprises a plurality of physical units, wherein the memory control circuit unit comprises:

a host interface configured to couple to a host system;

a memory interface, configured to couple to the rewritable non-volatile memory module; and

a memory management circuit, coupled to the host interface and the memory interface,

wherein the memory management circuit is configured to perform a data merge operation to store valid data collected from a source node to a recycling node,

wherein the source node comprises at least one first physical unit among the physical units, the recycling node comprises a second physical unit among the physical units, and

the data merge operation comprises:

sending a first read command sequence which instructs a reading of a first data from the at least one first physical unit by a first reading operation;

sending a first write command sequence which instructs a first stage programming operation on the second physical unit according to the first data;

sending a second read command sequence which instructs a reading of the first data from the at least one first physical unit again by a second reading operation after the first stage programming operation is performed; and

sending a second write command sequence which instructs a second stage programming operation on the second physical unit according to the first data read by the second reading operation.

16. The memory control circuit unit of claim 15 , wherein the source node further comprises at least one third physical unit among the physical units, the recycling node further comprises a fourth physical unit among the physical units, and the data merge operation further comprises:

sending a third read command sequence which instructs a reading of a second data from the at least one third physical unit; and

sending a third write command sequence which instructs a programming of the fourth physical unit according to the second data between the first stage programming operation and the second stage programming operation.

17. The memory control circuit unit of claim 15 , wherein the memory control circuit unit further comprises a buffer memory coupled to the memory management circuit, and the data merge operation further comprises:

storing the first data read by the first reading operation into the buffer memory temporarily, so as to provide the first data used in the first stage programming operation;

storing a second data into the buffer memory temporarily, wherein at least part of the first data read by the first reading operation is overwritten by the second data in the buffer memory; and

storing the first data read by the second reading operation into the buffer memory temporarily, so as to provide the first data used in the second stage programming operation.

18. The memory control circuit unit of claim 15 , wherein the memory management circuit is further configured to record read information in a management table and erase the at least one first physical unit according to the read information, and the read information reflects whether the at least one first physical unit is read by at least one of the first reading operation and the second reading operation.

19. The memory control circuit unit of claim 15 , wherein the second physical unit is programmed by the first stage programming operation and the second stage programming operation sequentially to store the first data.

20. The memory control circuit unit of claim 15 , wherein the first stage programming operation and the second stage programming operation belong to a multi stage programming operation, and at least three bits is stored in one memory cell of the second physical unit being programmed by the multi stage programming operation.

21. The memory control circuit unit of claim 15 , wherein the memory control circuit unit further comprises a buffer memory coupled to the memory management circuit, and the memory management circuit is further configured to store the first data read by the first reading operation or the second reading operation in the buffer memory temporarily,

wherein the second physical unit has a basic capacity, and an available capacity of the buffer memory is less than twice of the basic capacity.