JP6289883B2 - Storage device - Google Patents

Description

  Embodiments described herein relate to a storage apparatus.

In recent years, an increasing number of products use a storage medium using a flash memory called SSD (Solid State Drive), in particular a NAND flash memory, as database storage. Previously, databases were stored on file systems, but in the future, databases without file systems are expected to increase. In such a database without a file system, the transaction processing speed affects the performance of the database. For this reason, there is a need for a technique for promptly executing commit (reflection) and rollback (cancellation).
A conventional storage apparatus using a storage medium using NAND flash memory as database storage will be described.

  FIG. 15 is a functional block diagram showing a configuration example of a conventional storage apparatus that uses a storage medium using a NAND flash memory as a database storage.

The conventional storage apparatus 1A includes an input / output device 10, a data management unit 60 connected to the input / output device 10, a computing device 50 connected to the data management unit 60, and a non-volatile connected to the data management unit 60. The memory 40 and the volatile memory 30 </ b> A connected to the data management unit 60 are included.
The volatile memory 30 </ b> A includes a cache memory 31, an erased page list 32, a block state table 33, and a logical / physical conversion table 34.

  The input / output device 10 is an interface between the storage device 1A and a device such as a computer connected to the storage device 1A, and is, for example, a serial ATA (SATA).

  The data management unit 60 has a function of managing blocks and page states of the nonvolatile memory 40 and controlling reading and writing. The data management unit 60 is realized using, for example, a NAND memory controller chip. The data management unit 60 selects and erases blocks in which all pages are invalid, adds them to the erased page list 32, and acquires pages from the erased page list 32 when writing data.

The arithmetic device 50 has a function of performing an operation according to a request from the data management unit 60 and outputting an operation result. The arithmetic device 50 performs processing for obtaining a data storage destination and determining the status of data validity / invalidity.
The nonvolatile memory 40 is a memory that retains memory without supplying power, and is, for example, a NAND memory chip.

The volatile memory 30A is a memory that cannot hold stored information unless power is supplied, and is, for example, a DRAM. The volatile memory 30 </ b> A includes a cache memory 31, an erased page list 32, a block state table 33, and a logical / physical conversion table 34.
The cache memory 31 is a storage area for temporarily storing data.

  The erased page list 32 is a storage area for storing a list (data) of writable pages in the nonvolatile memory 40. When the data management unit 60 writes data into the nonvolatile memory 40, the data management unit 60 acquires a write destination page from the erased page list 32.

  The block state table 33 is a storage area for storing data for managing the page state of each block in the nonvolatile memory 40. The block state table 33 has states such as “valid”, “invalid”, and “erased” for each block.

  The logical-physical conversion table 34 is a storage area for storing data that holds the correspondence between the logical address and physical address of each page in the nonvolatile memory 40. FIG. 16 is a diagram illustrating an example of the logical / physical conversion table 34. The logical-physical conversion table 34 illustrated in FIG. 16 includes records corresponding to the logical address “0”, the logical address “1”, the logical address “2”, and the logical address “3”. The record corresponding to the logical address “0” stores the page “3” of the block “1” as the corresponding physical address. The record corresponding to the logical address “1” stores the page “0” of the block “4” as the corresponding physical address. The record corresponding to the logical address “2” stores the page “2” of the block “1” as the corresponding physical address. The record corresponding to the logical address “3” stores the page “1” of the block “2” as the corresponding physical address.

As shown in the contents of the logical-physical conversion table 34, the data corresponding to the logical address “0” is written in the page “3” of the block “1” of the nonvolatile memory 40. Data corresponding to the logical address “1” is written in the page “0” of the block “4” of the nonvolatile memory 40. Data corresponding to the logical address “2” is written in the page “2” of the block “1” of the nonvolatile memory 40. Data corresponding to the logical address “4” is written in the page “1” of the block “2” of the nonvolatile memory 40.
When the data is updated, the data management unit 60 always writes the update data to another physical address.

[Conventional storage device write processing (write operation)]
Next, write processing (write operation) of the conventional storage apparatus 1A will be described. FIG. 17 is a flowchart showing an example of write processing of the conventional storage apparatus 1A.

The conventional storage apparatus 1A, more specifically, the data management unit 60 acquires a write request to a certain logical address from an apparatus such as a computer via the input / output device 10 (S1710).
The data management unit 60 writes data (update data or the like) corresponding to this write request on the cache memory 31 of the volatile memory 30A (S1720).
Next, the data management unit 60 acquires a write destination physical page from the top of the erased page list 32 of the volatile memory 30A (S1730).

  Next, the data management unit 60 writes the data written in the cache memory 31 in step S1720 to the physical page acquired in step S1730 in the nonvolatile memory 40 (S1740).

  Next, the data management unit 60 rewrites the contents of the record corresponding to the logical address in the logical-physical conversion table 34 to the block number and page number corresponding to the physical page in which the data was written in step S1740 (S1750).

  Next, the data management unit 60 changes the state of the page of the block state table 33 corresponding to the previously registered physical address in the logical-physical conversion table 34 from “valid” to “invalid” (previously registered). (If the physical address used is a valid value) (S1760).

Next, the data management unit 60 changes the state of the corresponding page written in step S1740 in the block state table 33 from “erased” to “valid” (S1770).
Thus, the conventional storage apparatus 1A ends the write process.

[Conventional storage device erase processing (erase operation)]
Next, an erasing process (erasing operation) of the conventional storage apparatus 1A will be described. FIG. 18 is a flowchart showing an example of the erasing process of the conventional storage apparatus 1A.

  The conventional storage apparatus 1A, more specifically, the data management unit 60, determines whether or not the number of registered pages written in the erased page list 32 of the volatile memory 30A is equal to or less than a certain value (S1810). When it is determined that the number of registered pages written in the erased page list 32 is not below a certain level (S1810, No), the storage device 1, more specifically, the data management unit 60 ends the erase process.

  On the other hand, if it is determined in step S1810 that the number of registered pages is less than or equal to a certain number (S1810, Yes), the conventional storage apparatus 1A, more specifically, the data management unit 60, stores the block state table 33 of the volatile memory 30. Then, a block in which all pages are “invalid” is selected (S1820).

  Next, the conventional storage apparatus 1A, more specifically, the data management unit 60 erases the data written in the block of the nonvolatile memory 40 selected in step S1820 (S1830).

  Next, the conventional storage device 1A, more specifically, the data management unit 60 sets the state recorded in the block state table 33 of the volatile memory 30 to “erased” for all pages of the block selected in step S1820. Change (S1840).

Next, the storage device 1, more specifically, the data management unit 60 adds the page erased in step S1830 to the erased page list 32 of the volatile memory 30A (S1850).
Thus, the conventional storage device 1A ends the erasing process (erasing operation).
[Conventional storage device transaction commit processing]

  A transaction commit process of the conventional storage apparatus 1A will be described. FIG. 19 is a flowchart showing an example of transaction / commit processing of the conventional storage apparatus 1A.

  First, a BEGIN sentence is input to a computer (not shown) connected to the conventional storage apparatus 1A (S3010). This starts a transaction. In response to the input of the BEGIN statement, the internal operation of the database is not performed (S3110).

  Next, following step S3010, a processing command statement (INSERT, UPDATE, etc.) to the database is input to a computer (not shown) connected to the storage apparatus 1A (S3020). In accordance with these processing instructions, the data management unit 60 updates the database according to the processing instructions on the cache memory 31 as an internal operation of the database (S3120).

Next, a COMMIT sentence is input to a computer (not shown) connected to the storage apparatus 1A (S3030). In response to the input of the COMMIT statement, as an internal operation of the database, the data management unit 60 writes the database on the cache memory 31 to the nonvolatile memory 40 (S3130).
Thus, the transaction / commit processing of the conventional storage apparatus 1A is completed.

[Conventional storage device transaction rollback processing]
A transaction / rollback process of the conventional storage apparatus 1A will be described. FIG. 20 is a flowchart showing an example of transaction / rollback processing of the conventional storage apparatus 1A.

  First, a BEGIN sentence is input to a computer (not shown) connected to the conventional storage apparatus 1A (S4010). This starts a transaction. In response to the input of the BEGIN statement, no internal operation is performed in the database (S4110).

  Next, following step S4010, a processing command statement (INSERT, UPDATE, etc.) to the database is input to a computer (not shown) connected to the conventional storage apparatus 1A (S4020). In response to these processing instructions, the data management unit 60 updates the database on the cache memory 31 according to the processing instructions as an operation inside the database (S4120).

Next, a ROLLBACK statement is input to a computer (not shown) connected to the conventional storage apparatus 1A (S4030). In response to the ROLLBACK statement, as an internal operation of the database, the data management unit 60 discards the database on the cache memory 31 (S4130).
Thus, the transaction / rollback process of the conventional storage apparatus 1A is completed.

JP 2006-209316 A

When a storage medium using NAND flash memory is used as database storage, there is a problem that it takes time to write data to the NAND flash memory after performing a commit operation during a transaction.
An object of the present invention is to provide a technique for executing transaction processing at high speed for both COMMIT and ROLLBACK.

  The embodiment of the present invention is proposed as a storage apparatus. The storage apparatus includes a nonvolatile memory, a cache memory, a first conversion table, a second conversion table, a first processing unit, and a second processing unit.

  The non-volatile memory stores a database. The cache memory temporarily stores the database. The first conversion table stores the logical address of data and the corresponding physical address of the nonvolatile memory in association with each other. The second conversion table stores the logical address of the data and the corresponding physical address of the non-volatile memory in association with each other. The first processing means receives a command statement that is an instruction for operating the database, interprets the command statement, determines a database change content, and based on the database change content, the database content on the cache memory And the logical address corresponding to the changed contents of the database on the cache memory is associated with the physical address on the nonvolatile memory capable of storing the data of the changed contents, and the second Is received, and the second conversion table content is reflected in the first conversion table when an instruction indicating that the result of transaction processing is reflected in the database is received. The second processing means writes the changed contents of the database on the cache memory to the nonvolatile memory in the background.

Functional block diagram showing a configuration example of the storage apparatus according to the present embodiment Flow chart showing an example of transaction commit processing of the storage device Flow chart showing an example of transaction rollback processing of a storage device A flowchart showing an example of transaction processing of the storage apparatus Flow chart showing an example of BEGIN statement processing Flow chart showing an example of command statement processing Flow chart showing an example of COMMIT processing Flow chart showing an example of ROLLBACK processing Example of stored contents of transaction logical / physical conversion table, logical / physical conversion table, and nonvolatile memory before transaction processing The figure which shows the example of the memory content of the transaction logical-physical conversion table of the state at the time of following FIG. 9, a logical-physical conversion table, and a non-volatile memory The figure which shows the example of the memory content of the transaction logical-physical conversion table of the state at the time following FIG. 10, a logical-physical conversion table, and a non-volatile memory FIG. 11 is a diagram showing an example of storage contents of a transaction logical-physical conversion table, a logical-physical conversion table, and a nonvolatile memory in a state at a time point subsequent to FIG. FIG. 11 is another diagram showing an example of stored contents of a transaction-logical / physical conversion table, a logical / physical conversion table, and a non-volatile memory in a state at the time point following FIG. (A) is a sequence diagram of transaction processing by a conventional method, and (B) is a sequence diagram of transaction processing by the storage apparatus according to the present embodiment. Functional block diagram showing a configuration example of a conventional storage device Diagram showing an example of a logical-physical conversion table A flowchart showing an example of write processing of a conventional storage apparatus A flowchart showing an example of a conventional storage apparatus erasing process Flow chart showing an example of transaction commit processing of a conventional storage device Flow chart showing an example of transaction rollback processing in a conventional storage device

Hereinafter, a storage apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0. Definition of terms]
Definitions of terms used in this specification will be described.

[0.1. Logical-physical conversion table]
The “logical / physical conversion table” is a table for converting a logical address into a physical address of a NAND flash memory.

[0.2. transaction]
A “transaction” refers to a process in which a series of processes are collectively performed as one work in a database.

[0.3. commit]
“Commit” refers to a process of reflecting the result of a transaction process in a database.

[0.4. roll back]
“Rollback” refers to a process of canceling the result of a transaction process.

[1. Embodiment of the Invention]
The embodiment of the present invention is proposed as a storage apparatus. This storage device is a device that shortens processing time by realizing transaction processing commit and rollback using a logical-physical conversion table.

  The storage device is an information processing device, and this information processing device includes an arithmetic processing unit (CPU), a main memory (RAM), a read-only memory (ROM), an input / output device (I / O), and when necessary Is a device having an external storage device such as a hard disk device.

[1.1. Configuration example]
A configuration of the storage apparatus according to the embodiment of the present invention will be described. FIG. 1 is a functional block diagram showing a configuration example of the storage apparatus according to the present embodiment. Note that the components shown in the functional block diagram are the functions of the storage device that are grouped by function and regarded as a block. The storage device is a physical component such as a board, device, circuit, or component that corresponds to each component. It does not mean that it must have components. “Connected” means that data, information, instructions, etc. can be sent, received, delivered, etc. It is not limited. The same applies to the description of the functional block diagrams of the other components in this specification.

  The storage device 1 includes an input / output device 10, a database processing unit 20 connected to the input / output device 10, an arithmetic device 50 connected to the database processing unit 20, and a data management unit 60 connected to the arithmetic device 50. The volatile memory 30 is connected to the database processing unit 20 and the data management unit 60, and the non-volatile memory 40 is connected to the database processing unit 20 and the data management unit 60.

  The database processing unit 20 includes an input / output unit 21 connected to the input / output device 10, a command interpretation / processing unit 22 connected to the input / output unit 21, and a save / read process connected to the command interpretation / processing unit 22. 23. The save / read processing 23 is connected to the nonvolatile memory 40, and data writing to the nonvolatile memory 40 and data reading from the nonvolatile memory 40 are possible.

  The volatile memory 30 includes a cache memory 31, an erased page list 32, a block state table 33, a logical / physical conversion table 34, and a transaction logical / physical conversion table 35.

  The database processing unit 20 has a function of reading, adding, and changing a database in accordance with an external command. The data management unit 60 writes data to the nonvolatile memory 40, and the database processing unit 20 rewrites cache data and the like on the volatile memory 30.

  The input / output unit 21 has a function of receiving a command statement related to database operation from the input / output device 10 and outputting the processing result of the command statement to the input / output device 10.

  The command interpreting / processing unit 22 has a function of receiving a command statement related to database operation from the input / output unit 21, interpreting the command statement, and outputting a database change content.

  The save / read processing 23 stores the contents of the database change in the cache memory 31 on the volatile memory 30, the erased page list 32, the block state table 33, the logical / physical conversion table 34, and the logical / physical conversion table for transactions. 35.

  The transaction logical-physical conversion table 35 is a storage area for storing data describing the correspondence between logical addresses and physical addresses generated from the start to the end of one transaction.

  Other components of the storage apparatus 1 have the same functions as those of the conventional storage apparatus 1A shown in FIG. Components having similar functions are denoted by the same reference numerals, and detailed description of these functions is omitted. The logical-physical conversion table 34 corresponds to the first conversion table of the present embodiment, the transaction logical-physical conversion table 35 corresponds to the second conversion table of the present embodiment, and the database processing unit 20 The data management unit 60 corresponds to the second processing unit of the present embodiment, and corresponds to the first processing unit of the present embodiment.

[2. Example of operation]
Next, the operation of the storage apparatus 1 will be described.
[2.1. Storage device transaction commit processing]
The transaction / commit processing of the storage apparatus 1 will be described. FIG. 2 is a flowchart showing an example of transaction / commit processing of the storage apparatus 1.

  First, a BEGIN sentence is input to a computer (not shown) connected to the storage device 1 (S1010). This starts a transaction. In response to the input of the BEGIN statement, no internal operation is performed in the database (S1110).

  Next, following step S1010, a command statement (processing command statement; INSERT, UPDATE, etc.) to the database is input to a computer (not shown) connected to the storage apparatus 1 (S1020). In response to these processing command statements, the database processing unit 20, more specifically, the input / output unit 21, receives processing command statements from a computer (not shown) via the input / output device 10. The command interpretation / processing unit 22 receives a processing command statement from the input / output unit 21 and interprets the processing command statement to determine the contents of database change. The saving / reading process 23 updates the database on the cache memory 31 based on the database change contents (S1120). The data management unit 60 then writes the contents of the database to the nonvolatile memory 40 based on the database on the cache memory 31 in the background. Note that the physical address for writing the contents of the database to the nonvolatile memory 40 is the write destination physical address (physical page) from the top of the erased page list 32.

  Further, the database processing unit 20, more specifically, the storage / reading process 23 refers to the cache memory 31, the erased page list 32, and the logical / physical conversion table 34, and processes logical / physical conversion information corresponding to the update data of the database. Write to the logical-object conversion table 35 (S1120).

Next, a COMMIT sentence is input to a computer (not shown) connected to the storage apparatus 1 (S1030). The input COMMIT statement is passed to the database processing unit 20, more specifically, the input / output unit 21 through the input / output device 10. The command interpreting / processing unit 22 receives a COMMIT statement from the input / output unit 21 and instructs the save / read processing 23 to reflect the contents of the transaction logical-physical conversion table 35 in the logical-physical conversion table 34 according to the COMMIT statement. Send. The saving / reading process 23 that has received this command reflects the contents of the transaction logical-physical conversion table 35 in the logical-physical conversion table 34 (S1130).
Thus, the transaction commit processing of the storage apparatus 1 is completed.

[2.2. Storage device transaction rollback processing]
A transaction rollback process of the storage apparatus 1 will be described. FIG. 3 is a flowchart showing an example of transaction / rollback processing of the storage apparatus 1.

  First, a BEGIN sentence is input to a computer (not shown) connected to the storage device 1 (S2010). This starts a transaction. In response to the input of the BEGIN statement, no internal operation is performed in the database (S2110).

  Next, following step S2010, a processing command statement (INSERT, UPDATE, etc.) to the database is input to a computer (not shown) connected to the storage device 1 (S2020). In response to these processing command statements, the database processing unit 20, more specifically, the input / output unit 21, receives processing command statements from a computer (not shown) via the input / output device 10. The command interpretation / processing unit 22 receives a processing command statement from the input / output unit 21 and interprets the processing command statement to determine the contents of database change. The saving / reading process 23 updates the database on the cache memory 31 based on the database change contents (S2120). The data management unit 60 then writes the contents of the database to the nonvolatile memory 40 based on the database on the cache memory 31 in the background.

  Further, the database processing unit 20, more specifically, the storage / reading process 23 refers to the cache memory 31, the erased page list 32, and the logical / physical conversion table 34, and processes logical / physical conversion information corresponding to the update data of the database. It writes in the theory conversion table 35 (S2120).

Next, a ROLLBACK statement is input to a computer (not shown) connected to the storage device 1 (S2030). The input ROLLBACK statement is passed to the database processing unit 20, more specifically, to the input / output unit 21 via the input / output device 10. The command interpretation / processing unit 22 receives a ROLLBACK statement from the input / output unit 21 and sends an instruction to the save / read processing 23 to delete the contents of the transaction logical-physical conversion table 35 in response to the ROLLBACK statement. The save / read processing 23 that has received the command deletes the contents of the transaction logical-physical conversion table 35 (S2130).
This completes the transaction rollback process of the storage apparatus 1.

[2.3. Transaction processing]
Next, transaction processing of the storage apparatus 1 will be described. FIG. 4 is a flowchart showing an example of transaction processing of the storage apparatus 1.

  In the transaction processing, first, the storage apparatus 1 executes BEGIN statement processing (S10). FIG. 5 is a flowchart showing an example of BEGIN statement processing. In the BEGIN statement processing, the storage device 1, more specifically, the database processing unit 20 and the data management unit 60 sets the transaction state to “start” with the reception of the BEGIN statement as a trigger (S11). This completes the BEGIN statement processing.

  Returning to FIG. 4, the description of the transaction processing will be continued. Subsequent to step S10, the storage device 1, more specifically, the database processing unit 20 and the data management unit 60, waits for a command (command statement) input, and if a command statement input is received, the content corresponding to the command statement (Hereinafter referred to as “command statement processing”) is executed (S20). FIG. 6 is a flowchart showing an example of command sentence processing, and the command sentence processing will be described with reference to this flowchart.

  In command statement processing, the storage device 1, more specifically the database processing unit 20, sends an INSERT statement that is a data registration request or an UPDATE statement that is a database update request via the input / output device 10 and the input / output unit 21. Receive (S210).

  Subsequent to step S210, the storage apparatus 1, more specifically, the database processing unit 20, interprets the received request (INSERT statement or UPDATE statement) and determines a write destination logical address (S220).

  Subsequent to step S220, the storage apparatus 1, more specifically, the database processing unit 20, writes registration data or update data corresponding to the request received in step S210 into the database developed on the cache memory 31 (S230). . Note that data on the cache memory 31 is written to the physical page of the nonvolatile memory 40 later by the data management unit 60.

Subsequent to step S230, the storage apparatus 1, more specifically, the database processing unit 20, acquires a write destination physical page from the top of the erased page list 32 (S240).
Subsequent to step S24O, the storage apparatus 1, more specifically, the database processing unit 20, determines whether or not it is in a transaction state (S250).

  When it is determined that the transaction state is established (S250, Yes), the storage apparatus 1, more specifically, the database processing unit 20, associates the logical address determined in step S220 with the physical address corresponding to the logical address, and It is registered in the transaction logical-physical conversion table 35 (S260). Subsequent to step S260, the storage apparatus 1, more specifically, the database processing unit 20, changes the state of the physical page acquired in step S240 from “erased” to “valid” in the block state table 33 (S270). After step S270, the storage device 1, more specifically the database processing unit 20, ends the command statement processing.

  On the other hand, if it is determined in step S250 that the transaction state is not established (S250, No), the storage apparatus 1, more specifically, the database processing unit 20, stores the physical corresponding to the logical address determined in step S220 in the logical-physical conversion table 34. Register the address (S280).

  Subsequent to step S280, the storage apparatus 1, more specifically, the database processing unit 20, changes the status information of the page of the block status table 33 corresponding to the physical address previously registered in the logical-physical conversion table 34 from “valid”. Change to “Invalid” (S290). The page status information is changed from “valid” to “invalid” only when the previously registered physical address is a valid value.

Subsequent to step S290, the storage apparatus 1, more specifically the database processing unit 20, proceeds to the above-described step S270 and continues command statement processing.
This is the end of the description of command statement processing.

  Returning to FIG. 4, the description of the transaction processing will be continued. Subsequent to step S20, the storage apparatus 1, more specifically, the database processing unit 20 and the data management unit 60, determines whether or not the command input is completed (S30). Specifically, it is determined whether the most recently received command statement is a COMMIT statement or a ROLLBACK statement.

  If it is determined in step S30 that the command input has not been completed (S30, No), the storage apparatus 1, more specifically, the database processing unit 20 and the data management unit 60 return to step S20 and input the next command statement. I wait.

  On the other hand, if it is determined in step S30 that the command input has been completed (S30, Yes), the storage apparatus 1, more specifically, the database processing unit 20 and the data management unit 60, describe the contents of a series of command statement input after the transaction starts. Accordingly, it is determined whether or not to reflect in the database (S40). Specifically, when the command sentence that has been input most recently is a COMMIT sentence, the storage apparatus 1, more specifically, the database processing unit 20 and the data management unit 60, determines that it is reflected in the database. On the other hand, when the most recently entered command statement is a ROLLBACK statement, the storage device 1, more specifically, the database processing unit 20 and the data management unit 60, determines that the command statement is not reflected in the database.

  When it is determined in step S40 that the data is to be reflected in the database (S40, Yes), the storage apparatus 1, more specifically, the database processing unit 20, executes COMMIT processing. FIG. 7 is a flowchart showing an example of the COMMIT process. In the COMMIT process, the storage device 1, more specifically, the database processing unit 20 reflects (transcribes) the contents of the transaction-physical-physical conversion table 35 in the logical-physical conversion table 34, and then the contents of the transaction-logical-physical conversion table 35 Is empty (deleted) (S310).

Subsequent to step S310, the storage apparatus 1, more specifically, the database processing unit 20, changes the page status of the block status table 33 corresponding to the physical address previously registered in the logical-physical conversion table 34 from “valid”. Change to “Invalid” (S320; if the previously registered physical address is a valid value).
Subsequent to step S320, the storage apparatus 1, more specifically, the database processing unit 20, ends the transaction state (S330).
This completes the COMMIT process.

  Returning to FIG. 4, the description of the transaction processing will be continued. When it is determined in step S40 that the data is not reflected in the database (S40, No), the storage device 1, more specifically, the database processing unit 20 and the data management unit 60 execute ROLLBACK processing (S50). FIG. 8 is a flowchart showing an example of the ROLLBACK process. In the ROLLBACK process, the storage apparatus 1, more specifically, the database processing unit 20, empties the transaction logical-physical conversion table 35 (S410).

Subsequent to step S410, the storage apparatus 1, more specifically, the database processing unit 20, sets the page status of the block status table 33 corresponding to the physical address registered in the transaction logical-physical conversion table 35 to “valid”. Is changed to “invalid” (S420).
Subsequent to step S420, the storage apparatus 1, more specifically, the database processing unit 20, ends the transaction state (S430).
This completes the ROLLBACK process.

Returning to FIG. 4, the description of the transaction processing will be continued. After executing the COMMIT process in step S50 or the ROLLBACK process in step S60, the storage apparatus 1, more specifically, the database processing unit 20, ends the transaction process.
This is the end of the description of the transaction process.

[2.4. Rewrite transaction logical / physical conversion table in transaction processing]
An example of rewriting the storage contents of the transaction logical / physical conversion table 35, logical / physical conversion table 34, and nonvolatile memory in the transaction processing (S10 to S60) described above will be described.

[2.4.1. Before transaction processing]
FIG. 9 shows an example of storage contents of the transaction logical-physical conversion table 35, the logical / physical conversion table 34, and the nonvolatile memory 40 before the transaction processing. Before transaction processing, the logical-physical conversion table 34 shown in FIG. 9 has records corresponding to the logical address “0”, the logical address “1”, the logical address “2”, and the logical address “3”. . The record corresponding to the logical address “0” stores the page “0” of the block “1” of the nonvolatile memory 40 as the corresponding physical address. The record corresponding to the logical address “1” stores the page “1” of the block “2” of the nonvolatile memory 40 as the corresponding physical address. The record corresponding to the logical address “2” stores the page “2” of the block “1” of the nonvolatile memory 40 as the corresponding physical address. The record corresponding to the logical address “3” stores the page “0” of the block “4” as the corresponding physical address. Correspondence between each record of the logical-physical conversion table 34 and the block and page of the nonvolatile memory 40 is indicated by an arrow line in the figure.

  At the time before the transaction processing, the transaction logical-physical conversion table 35 has not yet stored the correspondence between the logical address and the physical address.

[2.4.2. After starting transaction processing (1)]
Assume that the storage apparatus 1 receives the following command statement (SQL statement) after the state shown in FIG. 9.
BEGIN;
UPDATE table1 SET x1 = n WHERE id = m;

  The storage apparatus 1 that has received the BEGIN statement, more specifically, the database processing unit 20 starts a transaction state, interprets the contents of the UPDATE statement that follows this, determines a write destination logical address, and stores it in the cache memory 31. Write update data. In this example, it is assumed that the write destination logical address is “1”.

  Next, the storage apparatus 1, more specifically, the database processing unit 20, acquires a write destination physical page from the top of the erased page list 32. In this example, it is assumed that page “0” of block “3” is described at the top of the erased page list 32.

  Subsequent to the above, the storage apparatus 1, more specifically, the database processing unit 20 stores the write destination logical address “1” in the transaction logical-physical conversion table 35 and the block “of the nonvolatile memory 40 corresponding to the physical address corresponding thereto. 3 ”page“ 0 ”is registered. FIG. 10 shows an example of the contents stored in the transaction logical-physical conversion table 35, logical-physical conversion table 34, and nonvolatile memory in this state.

  The storage device 1, more specifically the data management unit 60, updates the cache memory 31 corresponding to the logical address “1” to the page “0” of the block “3” of the nonvolatile memory 40 in the background of the above processing. Perform the writing process.

[2.4.3. After transaction processing starts (2)]
Assume that the storage apparatus 1 further receives the following command statement (SQL statement) after the state shown in FIG.
UPDATE table1 SET x2 = n WHERE id = b;

  The storage device 1 that has received the UPDATE statement, more specifically, the database processing unit 20 interprets the contents of the UPDATE statement, determines the write destination logical address, and writes the update data to the cache memory 31. In this example, it is assumed that the write destination logical address is “2”.

  Next, the storage apparatus 1, more specifically, the database processing unit 20, acquires a write destination physical page from the top of the erased page list 32. In this example, it is assumed that page “2” of block “4” is described at the top of erased page list 32.

  Following the above, the storage apparatus 1, more specifically, the database processing unit 20, writes the logical address “2” to be written to the transaction logical-physical conversion table 35 and the block “ The page “2” of “4” is newly registered. FIG. 11 shows an example of stored contents of the transaction logical-physical conversion table 35, logical-physical conversion table 34, and nonvolatile memory in this state.

  The storage device 1, more specifically, the data management unit 60, updates the cache memory 31 corresponding to the logical address “2” to the page “2” of the block “4” of the nonvolatile memory 40 in the background of the above processing. Perform the writing process.

[2.4.4. After starting transaction processing (3)]
Assume that after the state shown in FIG. 11, the storage apparatus 1 further receives a COMMIT statement that is a command statement (SQL statement).

  The storage device 1 that has received the COMMIT statement, more specifically, the database processing unit 20 writes the contents of the transaction logical-physical conversion table 35 into the logical-physical conversion table 34. In this example, the storage device 1, more specifically, the database processing unit 20, stores the block “3” and page number “0” corresponding to the logical address “1” written in the transaction logical-physical conversion table 35. The block number and the page number corresponding to the logical address “1” of the physical conversion table 34 are written as the block number and the page number, the block “4” corresponding to the logical address “2” written in the transaction logical-physical conversion table 35 and the page number “2”. Is written as the block number and page number corresponding to the logical address “1” of the logical-physical conversion table 34.

Note that the data writing to the non-volatile memory 40 is executed in advance by the data management unit 60 every time a command statement is received in the background. Therefore, the non-volatile memory 40 newly started when a COMMIT statement is received. Writing to does not occur.
The storage device 1, more specifically, the database processing unit 20 deletes all data written in the transaction logical-physical conversion table 35.
FIG. 12 shows an example of storage contents of the transaction logical-physical conversion table 35, logical-physical conversion table 34, and nonvolatile memory in this state.

[2.4.5. After starting transaction processing (4)]
The operation when the storage apparatus 1 further receives a ROLLBACK statement as a command statement (SQL statement) after the state shown in FIG. 11 will be described.

The storage apparatus 1 that has received the ROLLBACK statement, more specifically, the database processing unit 20, deletes all the data written in the transaction logical-physical conversion table 35. The update data and additional data are written to the non-volatile memory 40 in advance in the background by the data management unit 60 when each command statement is received, but the block indicated by the logical-physical conversion table 34 Since the number and page number are the block number and page number of the contents before the update data and additional data are written, it is not necessary to delete or rewrite the nonvolatile memory 40.
FIG. 13 shows an example of storage contents of the transaction logical-physical conversion table 35, logical-physical conversion table 34, and nonvolatile memory in this state.

[3. advantage]
(1) According to the storage device 1 according to the present embodiment, transaction processing can be executed at high speed for both commit and rollback.

  In the case of only changing the volatile memory at the time of commit and rollback, the conventional method requires several hundred μs or more (when stored in NAND), whereas the storage apparatus 1 according to the present embodiment requires Complete within a few μs (in case of DRAM).

  FIG. 14A shows a sequence diagram of transaction processing according to the conventional method, and FIG. 14B shows a sequence diagram of transaction processing by the storage apparatus 1 according to the present embodiment for comparison.

  As shown in FIG. 14A, in the transaction processing according to the conventional method, the cache memory 31 is updated in accordance with the UPDATE statement and the INSERT statement, and then the update data and addition to the nonvolatile memory 40 are added after the processing of the COMMIT statement starts. Data is written.

  On the other hand, as shown in FIG. 14B, in the transaction processing by the storage apparatus 1 according to the present embodiment, the cache memory 31 is updated according to the UPDATE statement and the INSERT statement, and the writing to the nonvolatile memory 40 is performed. Run in the background. Further, at the time of processing the COMMIT statement, the processing can be completed only by rewriting the logical-physical conversion table 34 on the cache memory 31. That is, in the conventional method, writing to the non-volatile memory 40 could not be performed until COMMIT, but the storage apparatus 1 according to the present embodiment updates the non-volatile memory 40 behind the scenes, so that the transaction processing time is shortened. Is possible.

  (2) According to the storage device 1 according to the present embodiment, since the amount of volatile memory used can be reduced, it is effective when the amount of volatile memory is limited.

In the conventional method, the memory usage corresponding to the record size × the number of cases is necessary, whereas in the storage device 1 according to the present embodiment, the memory usage corresponding to one entry size × the number of the logical-physical conversion table is used. It ’s enough.

  For example, if 100 bytes x 10,000 and 1 entry size of the logical-physical conversion table 34 = 4 bytes, the required amount of volatile memory is 100 x 10,000 = 1,000 Kbytes in the conventional method. In the storage device 1 according to the present embodiment, 4 × 10,000 = 40 Kbytes, and the memory usage can be significantly reduced.

[4. Summary, etc.]
As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change, addition, a combination, etc. are possible in the range which does not deviate from the meaning of invention.

1, 1A ... Storage device; 10 ... I / O device; 20 ... Database processing unit; 30, 30A ... Volatile memory; 40 ... Non-volatile memory; 60: Data management department;

Claims (2)

Non-volatile memory for storing the database;
A cache memory for temporarily storing the database;
An erased page list for storing a physical address of a writable page in the nonvolatile memory;
A block state table for storing data for managing the state of the page of each block in the nonvolatile memory;
A first conversion table for storing a logical address of data and a physical address of the nonvolatile memory corresponding to the logical address;
A second conversion table for storing a logical address of data and a physical address of the nonvolatile memory corresponding to the logical address;
Receives a command statement is a command for operating the database, interprets the command statement to determine the logical address of the changes and the data in the database, based on the changes of the database, the database on the cache memory Changing the contents, obtaining a write destination physical address in the nonvolatile memory from the erased page list, and a logical address corresponding to the changed contents of the database on the cache memory, and the write destination physical address , association with, writing to the second conversion table, receives an instruction means to reflect the results of the transaction processing to the database, the contents of the second conversion table is reflected in the first conversion table, In the block state table, the write And enable the state of the page corresponding to the physical address, the first processing means shall be the disable state of the page corresponding to the change source physical address of said database,
Second processing means for writing the changed contents of the database on the cache memory in the background to the write destination physical address of the nonvolatile memory;
A storage device. When the first processing means receives an instruction meaning to cancel the transaction processing result, the second conversion table is not reflected in the first conversion table without reflecting the contents of the second conversion table. revoke the content, in the block state table, the disable state of the page corresponding to the write destination physical address
The storage apparatus according to claim 1.

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