Changes between Version 7 and Version 8 of S3/S3Model/SuperEntities
- Timestamp:
- 11/01/10 23:43:31 (14 years ago)
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S3/S3Model/SuperEntities
v7 v8 13 13 The primary resource (=instance table) contains the same ''super-key'' field as the component, thus the forward join of resource-to-component can be established as a natural join, i.e. without accessing the link table. 14 14 15 For the (seldom needed) backward join component-to-resource, the link table needs tobe involved because it contains the table name of the primary resource in the field {{instance_type}}.15 For the (seldom needed) backward join component-to-resource, the link table must be involved because it contains the table name of the primary resource in the field {{instance_type}}. 16 16 17 Disadvantage of the link table method is that the link table needs to be updated whenever a primary resource record is created, updated or deleted - which generates some (minimal) extra load on write, however, it is recommended to not use super-entities for resources where the extra load on write can give a serious performance problem (e.g. messages), or at least to keep the super-entity table lean and free of extra references.17 Disadvantage of the link table method is that the link table has to be updated whenever a primary resource record is created, updated or deleted - which generates some (minimal) extra load on write, however, it is recommended to not use super-entities for resources where the extra load on write can give a serious performance problem (e.g. messages), or at least to keep the super-entity table lean and free of extra references. 18 18 19 19 - ''code examples to follow...''