Database quiesce operations
View Patent ↗A technique to quiesce a database without causing after-arriving access requests to abnormally terminate interrogates database management system control structures associated with the database. Specified modifications to these control structures can be made so that subsequent access requests to the database (i.e., during quiesce operations) are not abnormally terminated. Once quiesced, regular or special purpose maintenance or testing operations, the starting or stopping of log keeping operations or similar operations may be made to the database. Once these are complete, the database control structures may be updated again to permit pending/scheduled access requests to proceed.
1. A method including executing instructions recorded on a non-transitory computer-readable storage media using at least one processor, the method comprising:
receiving a command to quiesce a target database;
identifying the target database;
modifying a control parameter for the target database at a first time in response to receiving the command;
scheduling one or more access requests for the target database received after the first time to execute at a later time, wherein the modified control parameter causes the scheduling of the one or more access requests after receiving the command to quiesce the target database;
allowing one or more in-flight transactions for the target database that are incomplete at the first time to complete, the time at which the one or more in-flight transactions complete being a second time;
writing data for the target database to permanent storage at a third time, the third time being after the second time;
modifying the control parameter for the target database at a fourth time; and
executing the one or more scheduled access requests, wherein the modified control parameter causes the execution of the one or more scheduled access requests after the fourth time.
2. The method of claim 1 , wherein the target database comprises a hierarchical database.
3. The method of claim 2 , wherein the hierarchical database comprises an Information Management System (IMS) database.
4. The method of claim 3 , wherein modifying the control parameter at a first time comprises modifying a specified byte field in a DDIR control block and modifying the control parameter at a fourth time comprises modifying the specified byte field in the DDIR control block.
5. The method of claim 4 , wherein writing data for the target database to permanent storage comprises performing a database CLOSE operation against the target database.
6. The method of claim 5 , wherein modifying the control parameter for the target database at a fourth time comprises placing the target database in an OPEN status.
7. The method of claim 1 , wherein modifying the control parameter at a first time comprises modifying more than one control parameter for the target database and modifying the control parameter at a fourth time comprises modifying more than one control parameter for the target database.
8. The method of claim 1 , further comprising performing a task against the target database after the third time and before the fourth time.
9. The method of claim 1 , wherein allowing one or more in-flight transactions comprises:
identifying one or more incomplete in-flight transactions for the target database; and
subsequently periodically attempting to identify in-flight transactions for the target database, stopping when no incomplete in-flight transactions are identified.
10. A non-transitory computer-readable storage medium storing instructions that when executed cause a processor to perform a process, the instructions comprising instructions to:
receive a command to quiesce a target database;
identify the target database;
modify a control parameter for the target database at a first time in response to receiving the command;
schedule one or more access requests for the target database received after the first time to execute at a later time, wherein the modified control parameter causes the scheduling of the one or more access requests after receiving the command to quiesce the target database;
allow one or more in-flight transactions for the target database that are incomplete at the first time to complete, the time at which the one or more in-flight transactions complete being a second time;
write data for the target database to permanent storage at a third time, the third time being after the second time;
modify the control parameter for the target database at a fourth time; and
execute the one or more scheduled access requests, wherein the modified control parameter causes the execution of the one or more scheduled access requests after the fourth time.
11. The non-transitory computer-readable storage medium of claim 10 , wherein the target database comprises a hierarchical database.
12. The non-transitory computer-readable storage medium of claim 11 , wherein the hierarchical database comprises an Information Management System (IMS) database.
13. The non-transitory computer-readable storage medium of claim 12 , wherein:
the instructions to modify the control parameter at a first time comprise instructions to modify a specified byte field in a DDIR control block; and
the instructions to modify the control parameter at a fourth time comprise instructions to modify the specified byte field in the DDIR control block.
14. A computer system, comprising:
memory; and
one or more programmable control devices, at least one of which is communicatively coupled to the memory, the memory having stored therein instructions for causing the one or more programmable control devices to:
receive a command to quiesce a target database;
identify the target database;
modify a control parameter for the target database at a first time in response to receiving the command;
schedule one or more access requests for the target database received after the first time to execute at a later time, wherein the modified control parameter causes the scheduling of the one or more access requests after receiving the command to quiesce the target database;
allow one or more in-flight transactions for the target database that are incomplete at the first time to complete, the time at which the one or more in-flight transactions complete being a second time;
write data for the target database to permanent storage at a third time, the third time being after the second time;
modify the control parameter for the target database at a fourth time; and
execute the one or more scheduled access requests, wherein the modified control parameter causes the execution of the one or more scheduled access requests after the fourth time.
15. The computer system of claim 14 , wherein the target database comprises a hierarchical database.
16. The computer system of claim 15 , wherein the hierarchical database comprises an Information Management System (IMS) database.
17. The computer system of claim 16 , wherein:
the instructions for causing the one or more programmable control devices to modify the control parameter at a first time comprise instructions for causing the one or more programmable control devices to modify a specified byte field in a DDIR control block; and
the instructions for causing the one or more programmable control devices to modify the control parameter at a fourth time comprise instructions for causing the one or more programmable control devices to modify the specified byte field in the DDIR control block.