Method and system to avoid space bloating during run-time compression
Methods, systems, and computer program products are provided to manage a database system. The method includes locking during a database system idle time access by the database system to a data page of a data allocation unit, compressing during the database system idle time a data stored in the locked data page, and recording during the database system idle time an indication that the compressed and locked data page includes free storage space, wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked data page. Thus, the data page may be compressed during idle time and the space freed therein may be used during a subsequent run time without the need for a reorganization of the data pages within the corresponding table (as in, for example, operation of a reorg+rebuild SQL command combination).
1. A method comprising:
locking, by one or more computing devices during an idle time of a database system, access by the database system to a data page;
compressing, by the one or more computing devices during the idle time of the database system, data stored in the locked data page while the data page is locked; and
recording, by the one or more computing devices during, the idle time of the database system, an indication that the locked data page includes free storage space in the locked data page,
wherein the data page is one of a plurality of data pages in a data allocation unit of the database system, and
wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked data page.
2. The method of claim 1 , further comprising:
unlocking, by the one or more computing devices, access to the locked and compressed data page; and
storing, by the one or more computing devices during a run time of the database system, a second data in the compressed data page based on the indication that the compressed data page includes free storage space.
3. The method of claim 2 , further comprising:
recording, by the one or more computing devices during the run time of the database system, an indication that the current data page for storing data is the compressed data page; and
deleting, by the one or more computing devices during the run time of the database system, the indication that the compressed data page includes free storage space.
4. The method of claim 2 , further comprising:
recording, by the one or more computing devices during the run time of the database system, an indication that a second data page of the data allocation unit is full;
locking, by the one or more computing devices during a second idle time of a database system, access by the database system to the second data page; and
compressing, by the one or more computing devices during the second idle time of the database system, data stored in the locked second data page,
wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked second data page.
5. The method of claim 1 , wherein
the database system comprises a memory partition for storing data pages,
the memory partition includes a partition descriptor data structure for storing information about stored data pages, and
the recording of the indication that the compressed and locked data page includes free storage space comprises recording the indication in a partition description data structure corresponding to the partition of the locked and compressed data page.
6. A method comprising:
storing, by one or more computing devices during a ran time of a database system, data in a data page that includes a compressed data based on an indication that the data page includes space freed by a compression of data.
7. The method of claim 6 , further comprising:
allocating, by the one or more computing devices during the run time of the database system, a second data page for storing data based on an indication that no previously-allocated and previously-compressed data page includes space freed by a compression of data.
8. The method of claim 7 , further comprising:
recording, by the one or more computing devices during the run time of the database system, an indication that the second data page is full;
compressing, by the one or more computing devices during an idle time of the database system subsequent to the run time of the database system, data stored in the second data page; and
recording, by the one or more computing devices, an indication that the second data page includes space freed by a compression of data.
9. A database system comprising:
a memory; and
at least one processor coupled to the memory and configured to:
lock, during an idle time of the database system, access to a data page;
compress, during the idle time of the database system, data stored in the locked data page while the data page is locked; and
record, during the idle time of the database system, an indication that the locked data page includes free storage space in the locked data page,
wherein the data page is one of a plurality of data pages in a data allocation unit of the database system, and
wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked data page.
10. The database system of claim 9 , the at least one processor further configured to:
unlock access to the locked and compressed data page; and
store, during a run time of the database system, a second data in the compressed data page based on the indication that the compressed data page includes free storage space.
11. The database system of claim 10 , the at least one processor further configured to:
record, during the run time of the database system, an indication that the current data page for storing data is the compressed data page; and
delete, during the run time of the database system, the indication that the compressed data page includes free storage space.
12. The database system of claim 10 , the at least one processor further configured to:
record, during the run time of the database system, an indication that a second data page of the data allocation unit is full;
lock, during a second idle time of a database system, access by the database system to the second data page; and
compress, during the second idle time of the database system, data stored in the locked second data page,
wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked second data page.
13. The database system of claim 9 , the at least one processor further configured to:
store data pages according to a memory partition, wherein the memory partition includes a partition descriptor data structure for storing information about stored data pages; and
record the indication that the compressed and locked data page includes free storage by recording the indication in a partition description data structure corresponding to the partition of the locked and compressed data page.
14. A computer-readable storage device having stored thereon instructions, execution of which, by a computing device, cause the computing device to perform operations comprising:
locking, by one or more computing devices during an idle time of a database system, access by the database system to a data page;
compressing, by the one or more computing devices during the idle time of the database system, data stored in the locked data page while the data page is locked; and
recording, by the one or more computing devices during the idle time of the database system, an indication that the locked data page includes free storage space in the locked data page,
wherein the data page is one of a plurality of data pages in a data allocation unit of the database system, and
wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked data page.
15. The computer-readable storage device of claim 14 , the operations further comprising:
unlocking, by the one or more computing devices, access to the locked and compressed data page; and
storing, by the one or more computing devices during a run time of the database system, a second data in the compressed data page based on the indication that the compressed data page includes free storage space.
16. The computer-readable storage device of claim 15 , the operations further comprising:
recording, by the one or more computing devices during the run time of the database system, an indication that the current data page for storing data is the compressed data page; and
deleting, by the one or more computing devices during the run time of the database system, the indication that the compressed data page includes free storage space.
17. The computer-readable storage device of claim 15 , the operations further comprising:
recording, by the one or more computing devices during the run time of the database system, an indication that a second data page of the data allocation unit is full;
locking, by the one or more computing devices during a second idle time of a database system, access by the database system to the second data page; and
compressing, by the one or more computing devices during the second idle time of the database system, data stored in the locked second data page,
wherein unlocked data pages of the data allocation unit are accessible by the database system during the compressing of the data stored in the locked second data page.
18. The computer-readable storage device of claim 14 , wherein
the database system comprises a memory partition for storing data pages,
the memory partition includes a partition descriptor data structure for storing information about stored data pages, and
the recording of the indication that the compressed and locked data page includes free storage space comprises recording the indication in a partition description data structure corresponding to the partition of the locked and compressed data page.