Atomic visibility switch for transactional cache invalidation
Disclosed herein are systems, methods, and computer program products for providing transaction-consistent snapshots of data stored in or associated with a database. An embodiment operates by receiving, at a source database, an update request to update data associated with a table stored at the source database, and modifying a value of a modification-in-progress data structure corresponding to the table to indicate that a modification is in progress for the table. The embodiment includes updating a value of a commit identification counter and a table time stamp associated with the table to indicate that cached data having a time stamp older than the updated time stamp are invalid. The embodiment further includes modifying the value of the modification-in-progress counter to indicate completion of table modification.
1. A method, comprising:
receiving, by one or more computing devices, at a source database, an update request to update data associated with a table stored at the source database;
modifying, by the one or more computing devices, a modification-in-progress data structure corresponding to the table to indicate that a modification is in progress for the table;
updating, by the one or more computing devices, data in the table based on the update request;
updating, by the one or more computing devices, a commit identification data structure to reflect that the source database has been updated;
updating, by the one or more computing devices, the value of a source table time stamp corresponding to the table based on the commit identification data structure;
modifying, by the one or more computing devices, the value of the modification-in-progress data structure to indicate that no modification is in progress for the table upon updating the value of the source table time stamp; and
responding, by the one or more computing devices, to a request from a cache node holding a cached copy of the table with an indication that the cached copy is invalid based on either the modification-in-progress data structure indicating that a modification is in progress for the table, or the value of the source table time stamp being more recent than a time stamp corresponding to the cached copy of the table.
2. The method of claim 1 , wherein modifying the modification-in-progress data structure comprises selecting the modification-in-progress data structure corresponding to the table from a plurality of modification-in-progress data structures corresponding to respective tables from a plurality of tables stored at the source database.
3. The method of claim 1 , further comprising:
transmitting an update comprising a subset of data in the table to the cache node.
4. The method of claim 1 , wherein the cache node comprises a cached entity including a copy of a subset of data in the table and wherein the cache node further comprises a cache key associated with the cached entity, the method further comprising:
directing a request for data associated with the table to the cache node if the cache key matches a request key associated with the request.
5. The method of claim 1 , wherein the cache node comprises a cached entity including a copy of a subset of data in the table and wherein the cache node comprises a time stamp associated with the cached entity, further comprising:
directing a request for data associated with the table to the cache node if the cache key matches a request key associated with the request based on a comparison of the time stamp associated with the cached entity to the source table time stamp.
6. The method of claim 1 , wherein the cache node comprises a cached entity including a copy of a subset of data in the table and wherein the cached entity further comprises a copy of a subset of data in another table stored at the source database.
7. The method of claim 1 , further comprising:
writing a commit log to a non-volatile storage device.
8. A system comprising:
a memory; and
at least one processor coupled to the memory and configured to:
receive, at a source database, an update request to update data associated with a table stored at the source database;
modify a modification-in-progress data structure corresponding to the table to indicate that a modification is in progress for the table;
update data in the table based on the update request;
update a commit identification data structure to reflect that the source database has been updated;
update the value of a source table time stamp corresponding to the table based on the commit identification data structure;
modify the value of the modification-in-progress data structure to indicate that no modification is in progress for the table upon updating the value of the source table time stamp; and
respond to a request from a cache node holding a cached copy of the table with an indication that the cached copy is invalid based on either the modification-in-progress data structure indicating that a modification is in progress for the table, or the value of the source table time stamp being more recent than a time stamp corresponding to the cached copy of the table.
9. The system of claim 8 , wherein modifying the modification-in-progress data structure comprises selecting the modification-in-progress data structure corresponding to the table from a plurality of modification-in-progress data structures corresponding to respective tables from a plurality of tables stored at the source database.
10. The system of claim 8 , the at least one processor further configured to:
transmit an update comprising a subset of data in the table to the cache node.
11. The system of claim 8 , wherein the cache node comprises a cached entity including a copy of a subset of data in the table and wherein the cache node further comprises a cache key associated with the cached entity, and the at least one processor is further configured to:
direct a request for data associated with the table to the cache node if the cache key matches a request key associated with the request.
12. The system of claim 8 , wherein the cache node comprises a cached entity including a copy of a subset of data in the table and wherein the cache node comprises a time stamp associated with the cached entity, and the at least one processor is further configured to:
direct a request for data associated with the table to the cache node if the cache key matches a request key associated with the request based on a comparison of the time stamp associated with the cached entity to the source table time stamp.
13. The system of claim 8 , wherein the cache node comprises a cached entity including a copy of a subset of data in the table and wherein the cached entity further comprises a copy of a subset of data in another table stored at the source database.
14. The system of claim 8 , wherein the at least one processor is further configured to write a commit log to a non-volatile storage device.
15. A non-transitory computer-readable device having instructions stored thereon that, when executed by at least one computing device, causes the at least one computing device to perform operations comprising:
receiving, by one or more computing devices, at a source database, an update request to update data associated with a table stored at the source database;
modifying, by the one or more computing devices, a modification-in-progress data structure corresponding to the table to indicate that a modification is in progress for the table;
updating, by the one or more computing devices, data in the table based on the update request;
updating, by the one or more computing devices, a commit identification data structure to reflect that the source database has been updated;
updating, by the one or more computing devices, the value of a source table time stamp corresponding to the table based on the commit identification data structure;
modifying, by the one or more computing devices, the value of the modification-in-progress data structure to indicate that no modification is in progress for the table upon updating the value of the source table time stamp; and
responding, by the one or more computing devices, to a request from a cache node holding a cached copy of the table with an indication that the cached copy is invalid based on either the modification-in-progress data structure indicating that a modification is in progress for the table, or the value of the source table time stamp being more recent than a time stamp corresponding to the cached copy of the table.
16. The non-transitory computer-readable device of claim 15 , wherein modifying the modification-in-progress data structure comprises selecting the modification-in-progress data structure corresponding to the table from a plurality of modification-in-progress data structures corresponding to respective tables from a plurality of tables stored at the source database.
17. The non-transitory computer-readable device of claim 15 , the operations further comprising:
transmitting an update comprising a subset of data in the table to the cache node.