The basic data model was invented a half-century ago. Expressiveness of basic SQL is not different depending on the engine. Relational algebra is the same however it's implemented.
Some databases have extensions, and those are okay to include. You should be able to either (1) choose to not use those or (2) lock yourself into a subset of databases which support the extension you need.
It's good if those extension were namespaced. For example:
* If I want to use a postgres JSON type, it should live under postgres.json (or if it cuts across multiple databases, perhaps extensions.json or similar)
* Likewise, database built-in functions, except for common ones like min/max/mean, should be available under the namespace of those databases.
* It's okay if some of those are abstracted out into a namespace like extensions.math, so I can use extensions.math.sin no matter whether the underlying datastore decided to call it SINE, SIN, SINE_RADIANS, SIN(x/180*PI), and if it doesn't have sine, an exception gets raised.
The basic relational data model provides the best expressiveness for representing data and queries created to date, and doesn't differ. It's a good theoretical model, and it works well in practice. There's good reason it's survived this long, despite no lack of competition. The places expressiveness differs are relatively surface things like data types and functions.
It's also okay to have compound types, where I am explicit about what the type is in different databases. e.g.: string_type = {mysql: 'TEXT', postgresql: ...
blagie|2 years ago
The basic data model was invented a half-century ago. Expressiveness of basic SQL is not different depending on the engine. Relational algebra is the same however it's implemented.
Some databases have extensions, and those are okay to include. You should be able to either (1) choose to not use those or (2) lock yourself into a subset of databases which support the extension you need.
It's good if those extension were namespaced. For example:
* If I want to use a postgres JSON type, it should live under postgres.json (or if it cuts across multiple databases, perhaps extensions.json or similar)
* Likewise, database built-in functions, except for common ones like min/max/mean, should be available under the namespace of those databases.
* It's okay if some of those are abstracted out into a namespace like extensions.math, so I can use extensions.math.sin no matter whether the underlying datastore decided to call it SINE, SIN, SINE_RADIANS, SIN(x/180*PI), and if it doesn't have sine, an exception gets raised.
The basic relational data model provides the best expressiveness for representing data and queries created to date, and doesn't differ. It's a good theoretical model, and it works well in practice. There's good reason it's survived this long, despite no lack of competition. The places expressiveness differs are relatively surface things like data types and functions.
It's also okay to have compound types, where I am explicit about what the type is in different databases. e.g.: string_type = {mysql: 'TEXT', postgresql: ...