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Row-Based Administration Costs of Internal Tables

In addition to the basic memory requirement described in Memory requirement for deep data objects required to administrate internal tables in table headers, additional memory is required to administrate each individual row, so permitting optimized access to the individual rows. This internal administration of individual rows has two variants:

How a table row is administrated depends on the table category and any existing secondary table keys. The table category determines the basic administration of the rows of an internal table (table index for index tables, hash administration for hashed tables). Each additional secondary table key introduces additional row administration (table index for sorted keys, hash administration for hashed keys).

Indexes are therefore created in the following cases:

Hash administrations are created in the following cases:

If secondary table keys are used, additional memory costs may be incurred.

Examples

Following an access using DELETE or SORT, the memory requirement per row jumps to 6 bytes for the primary index and 30 bytes for the hash administration.