Walter Meester
HoogkarspelPays-Bas
Erik,
>>Yep this is a drawback, however I don't like the 128 bit (16 bytes) PK value either. It consumes too much memory.
>Is this really a practical concern? In what situation would this be a problem?
In nadya's case this is certainly a practical problem. If your table is growing towards 2GIG you certainly don't want a (n extra) PK of 16 bytes.
If for example I have a linking table with 3 foreign keys, which combined form a unique (PK) key, you can implement it in the folowing ways
1. a table that consist of three integer fields: 13 bytes record lenght
2. a table that consist of three 16 bytes character fields 49: bytes record lenght.
3 a table that consist of three 16 bytes character fields + 16 byte PK: 65 bytes record lenght.
The difference between 1 and 3 is 500%. This not only means that table 1 can contain 5 times more records than table 3, but also that performance is seriously affected because of larger indexkeys (because of the nature of the 128 bit key: it can not be compressed much, if at all). Rushmore actions require lots more of memory etc..
Walter,
Précédent
Suivant
Répondre
Voir le fil de ce thread
Voir le fil de ce thread à partir de ce message seulement
Voir tous les messages de ce thread
Voir tous les messages de ce thread à partir de ce message seulement