Key-value based data storage device and operation method thereof
A key-value (KV) based data storage device configured to process one or more range query commands includes a first table, summary data, a Log-Structured merge (LSM) tree area storing a plurality of second tables forming an LSM tree structure, and a value log area storing a value corresponding to a key stored in the LSM tree structure. The summary data includes version data including a global version representing current states of the first table and the plurality of second tables. The KV based storage device adds a copy version of the global version in the version data when initiating processing of a range query command and refers to that copy version while processing that range query command.
1. A key-value (KV) based data storage device comprising:
a first memory storing a first table and a summary data;
a second memory including a Log-Structured merge (LSM) tree area storing a plurality of second tables forming an LSM tree structure and a value log area storing a value corresponding to a key; and
a controller configured to process a range query command,
wherein the summary data includes version data including a global version representing current states of the first table and the plurality of second tables, and
wherein the controller adds a copy version of the global version in the version data at the beginning of a processing of the range query command and refers to the copy version while processing the range query command.
2. The KV based data storage device of claim 1 , wherein the controller deletes the copy version in the version data in response to processing of the range query command being completed.
3. The KV based data storage device of claim 1 , wherein the global version includes first table information corresponding to the first table and a plurality of second table information corresponding to the plurality of second tables, and each second table information includes an address of a corresponding second table and key range information.
4. The KV based data storage device of claim 1 , wherein the summary data further includes a metadata pool including a plurality of second table information corresponding to the plurality of second tables, and
wherein the global version includes pointer information to second table information included in the metadata pool corresponding to the plurality of second tables.
5. The KV based data storage device of claim 4 , wherein each of the plurality of second table information includes a reference counter, and wherein the control circuit increases reference counters in the plurality of second table information related to a corresponding copy version in response to processing of the range query command being initiated, and decreases reference counters in the plurality of second table information related to the corresponding copy version in response to processing of the range query command being completed.
6. The KV based data storage device of claim 5 , wherein when a second table is deleted in the LSM tree area, the control circuit determines whether corresponding second table information in the metadata pool should be deleted by referring to a reference counter of the corresponding second table information.
7. The KV based data storage device of claim 6 , wherein the control circuit adds a plurality of second table information corresponding to a plurality of second tables included in the LSM tree area in the metadata pool when creating the global version and sets reference counters included in the plurality of second table information as 1.
8. The KV based data storage device of claim 7 , wherein the control circuit sets a reference counter of corresponding second table information as 1 and adds the corresponding second table information in the metadata pool in response to a second table being added in the LSM tree area, and the control circuit decreases a reference counter of corresponding second table information by 1 in the metadata pool in response to a second table being deleted in the LSM tree area.
9. The KV based data storage device of claim 8 , wherein the control circuit deletes second table information in the metadata pool when a reference counter corresponding to the second table information is 0.
10. An operation method of a key-value (KV) based data storage device including a first table, summary data, a Log-structured merge (LSM) tree area including a plurality of second tables forming an LSM tree structure, and a value log area, the method comprising:
adding a global version representing current states of the first table and the plurality of second tables in version data in the summary data;
adding a copy version corresponding to a copy of the global version in the version data when processing of a range query command is initiated;
referring to the copy version while processing the range query command; and
deleting the copy version in the version data in response to processing of the range query command being completed.
11. The operation method of the claim 10 , wherein the summary data further incudes a metadata pool including a plurality of second table information corresponding to the plurality of second tables, and
wherein the global version includes pointer information to second table information included in the metadata pool and corresponding to the plurality of second tables.
12. The operation method of the claim 11 , wherein the plurality of second table information include a plurality of reference counters, respectively,
wherein adding the global version in the version data includes increasing reference counters in a plurality of second table information related to the copy version, and
wherein deleting the copy version in the version data includes decreasing reference counters in the plurality of second table information related to the copy version.
13. The operation method of the claim 12 , further comprising determining whether second table information should be deleted with reference to a reference counter of the second table information in the metadata pool in response to a corresponding second table being deleted in the LSM tree area.
14. The operation method of the claim 13 , wherein adding the global version in the version data includes adding a plurality of second table information corresponding to a plurality of second tables stored in the LSM tree area in the metadata pool and setting reference counters in the plurality of second table information as 1.
15. The operation method of the claim 14 , further comprising adding second table information in the metadata pool by setting a corresponding reference counter as 1 when adding a corresponding second table in the LSM tree area, and decreasing a reference counter of second table information by 1 in the metadata pool when deleting a corresponding second table in the LSM tree area.
16. The operation method of the claim 15 , further comprising deleting second table information in the metadata pool when a corresponding reference counter is 0.