Why EAV is bad?
Disadvantages of using an Entity Attribute Value (EAV) Model Data validation becomes harder: The value on the “Attribute_Value” table tends to be stored in a data-type like “varchar”. This makes validation of the data harder. Of course you can start to add validation yourself, but this is adding complexity.
What EAV means?
The Equalized Assessed Value (EAV) of your property is the product of the assessed value of your property (both land and improvements) and the State Equalization Factor, which is set by the Illinois Department of Revenue.
Is it good or bad to use EAV?
EAV gives a flexibility to the developer to define the schema as needed and this is good in some circumstances. On the other hand it performs very poorly in the case of an ill-defined query and can support other bad practices.
When do you need generic attributes in EAV?
EAV is all fun and games until you need some specific business logic. It is very likely that the logic will need some of the generic attributes that are identified as specific attributes. What this means in a practical sense is that a generic attribute – Price – will be used to do some special calculation, and you will need a way to find that data.
Which is an example of an EAV model?
Example of an EAV model The generic entity we need is the Product. Instead of having a Product table that, with a constant set of columns, represents actual products, we can create a ProductDefinitions table. This table will contain only the columns needed to define a product type, rather than columns that define actual instances of that product.
Why do we use EAV structure in SQL?
Using an EAV structure for has several implications that are trade offs. You are trading off a ‘less space for the row because you don’t have 100 columns that are null ‘ against ‘more complex queries and model’. Having an EAV typically means the value is a string that one can stuff any data into.