Tracking row and object database activity into block level heatmaps
A method, apparatus, and system for tracking row and object database activity into block level heatmaps is provided. Database activity including reads, writes, and creates can be tracked by a database management system at the finest possible level of granularity, or the row and object level. To efficiently record the tracked database activity, a two-part structure is described for writing the activity into heatmaps. A hierarchical in-memory component may use a dynamically allocated sparse pool of bitmap blocks. Periodically, the in-memory component is persisted to a stored representation component, sharable with multiple database instances, which may include consolidated last access times and/or a history of heatmap snapshots to reflect access over time. The heatmaps may then be externalized to database users and applications to provide and support a variety of features.
1. A method comprising:
persisting a linked list of map blocks, wherein:
each map block of the linked list of map blocks contains a mapping from each LBA range of a respective plurality of ranges of logical block addresses (LBAs) to a respective statistics block that contains access activity statistics of a plurality of data blocks in the LBA range,
the linked list of map blocks contains a first map block and a second map block, and
the first map block contains a link that refers to the second map block;
accessing the first map block and, based on said link in the first map block, the second map block;
detecting, based on a plurality of statistic blocks that are indicated by said mappings in the first map block and second map block and without accessing a plurality of data blocks in a database object that is a tablespace, an allocation stripe of a disk array, or a relational table, whether the database object has or has not been accessed since a particular time; and
copying the tablespace, the allocation stripe, or the relational table in response to said detecting whether the database object has or has not been accessed.
2. The method of claim 1 wherein said persisting the linked list of map blocks comprises:
contiguously storing the linked list of map blocks in said allocation stripe, or
not contiguously storing the linked list of map blocks.
3. The method of claim 1 wherein said persisting the linked list of map blocks comprises storing the link in the first map block that refers to the second map block.
4. The method of claim 1 wherein said persisting the linked list of map blocks comprises persisting an index that refers to the first map block and the second map block.
5. The method of claim 1 wherein said persisting the linked list of map blocks comprises storing the linked list of map blocks as part of a second tablespace.
6. The method of claim 5 wherein the second tablespace is at least one selected from the group consisting of: said tablespace, a user data tablespace, and a metadata tablespace.
7. The method of claim 1 wherein said access activity statistics comprise a last access timestamp for each data block of said plurality of data blocks in the LBA range.
8. The method of claim 7 wherein said last access timestamp for each data block comprises a last read timestamp.
9. The method of claim 7 wherein said last access timestamp for each data block consists of one selected from the group consisting of: 32 bits and 64 bits.
10. The method of claim 1 wherein said access activity statistics consists of a fixed size record for each data block of said plurality of data blocks in the LBA range.
11. The method of claim 1 wherein said copying in response to said detecting whether the database object has or has not been accessed comprises archiving the database object.
12. One or more non-transitory computer-readable media storing instructions that, when executed by one or more processors, cause:
persisting a linked list of map blocks, wherein:
each map block of the linked list of map blocks contains a mapping from each LBA range of a respective plurality of ranges of logical block addresses (LBAs) to a respective statistics block that contains access activity statistics of a plurality of data blocks in the LBA range,
the linked list of map blocks contains a first map block and a second map block, and
the first map block contains a link that refers to the second map block;
accessing the first map block and, based on said link in the first map block, the second map block;
detecting, based on a plurality of statistic blocks that are indicated by said mappings in the first map block and second map block and without accessing a plurality of data blocks in a database object that is a tablespace, an allocation stripe of a disk array, or a relational table, whether the database object has or has not been accessed since a particular time; and
copying the tablespace, the allocation stripe, or the relational table in response to said detecting whether the database object has or has not been accessed.
13. The one or more non-transitory computer-readable media of claim 12 wherein said persisting the linked list of map blocks comprises:
contiguously storing the linked list of map blocks in said allocation stripe, or
not contiguously storing the linked list of map blocks.
14. The one or more non-transitory computer-readable media of claim 12 wherein said persisting the linked list of map blocks comprises storing the link in the first map block that refers to the second map block.
15. The one or more non-transitory computer-readable media of claim 12 wherein said persisting the linked list of map blocks comprises persisting an index that refers to the first map block and the second map block.
16. The one or more non-transitory computer-readable media of claim 12 wherein said persisting the linked list of map blocks comprises storing the linked list of map blocks as part of a second tablespace.
17. The one or more non-transitory computer-readable media of claim 16 wherein the second tablespace is at least one selected from the group consisting of:
said tablespace, a user data tablespace, and a metadata tablespace.
18. The one or more non-transitory computer-readable media of claim 12 wherein said access activity statistics comprise a last read timestamp.
19. The one or more non-transitory computer-readable media of claim 12 wherein said access activity statistics consist of a fixed size record for each data block of said plurality of data blocks in the LBA range.
20. The one or more non-transitory computer-readable media of claim 12 wherein said copying in response to said detecting whether the database object has or has not been accessed comprises archiving the database object.