Database Denormalisation

Tags

soft-eng

Is the act of un-(/brain/20210815023015-database_normalisation/) a database. This could be [see page 22, valuable] to increase the efficiency of searches (fewer joins) or to decrease the fragmentation of data (fewer tables).

Denormalisation can be done by:

• Reducing the number of tables.

  Approaches involve avoiding reconstructing whole objects in memory from fragmented table data, resulting in fewer joins.

  • Flattening the database structure into one table leading to wasted space due to excess null values.
  • Flatenning composition structures into one table at the cost of replicating the part data many times in the whole.

• Optimising the access paths

  Saving time when searching resulting in fewer joins.

  • Retains redundant access path through the data but at the cost of additional FKs and the risk of inconsistency between them.