Maintaining IP-Tables

The general idea is that there are IP-tables for individual temporal relations stored in the database catalog . Obviously, one wants to avoid that an IP-table I(R) (or I'(R,a) or I''(R)) is recomputed each time when a temporal relation R is changed through an update. Essentially, one could take two approaches:

• One can argue that a few new, changed or deleted tuples/intervals within a temporal relation do not translate into severe changes within an IP-table. Consequently, such changes will not have a great impact on the quality of the partitions that are created from the information stored in the IP-table. Only after a certain period, i.e. after a major number of updates have been performed, one should recompute the IP-table. In other words: an IP-table is not updated; only when its information is likely to differ too much from the actual state of the corresponding temporal relation then it is entirely recomputed.
  Obviously, this option is only convenient for situations in which newly inserted data has timestamps  that are well distributed over the timeline. In the case of transaction time applications, for example, new data has timestamps beyond the end of the current lifespan. In terms of an IP-table this means that there is one or more `hot spots' at which values would change. Thus the information provided by an IP-table would soon be obsolete for partitioning purposes if it was not updated.
• A second possibility is to maintain an IP-table. This means that the information within the IP-table is updated each time the corresponding temporal relation is updated. In this section, we describe the actions that have to be performed on an IP-table when a new tuple is inserted into and when a tuple is removed from the corresponding temporal relation. These actions slightly differ, depending on the type of IP-table that is used: section 7.4.1 describes those for complete IP-tables, section 7.4.2 the ones for condensed IP-tables and section 7.4.3 those for endpoint IP-tables.

• Maintaining Complete IP-Tables
• Maintaining Condensed IP-Tables
• Maintaining Endpoint IP-Tables