kdb+ has a variant of SQL which is an evolution (not a revolution). The advances basically fall into three categories:
1. Shortcuts, such as "foreign key chasing" - i.e., if "a" int table x is a reference to field b in table y then "a.c" is "select c from x inner join y on (x.a=y.b)"; If you have a star schema, it cuts down queries and errors by 90% (and makes life simple for the optimizer). Of course, you can chase through as many tables as you wish in an expression, making item tables look a lot more like records.
2. Embracing order; The relational model has no ordering among tuples; SQL mostly pretends that's the case, but the order does emerge through "ORDER BY / TOP" and "ROWID" but not very usefully so. kdb+ embraces order and makes e.g. "first record that ..." very simple and intuitive (and also easier for the optimizer).
3. Embracing time series (not independent from embracing order) - when you have e.g. records with a "from .. to" validity range, it becomes exceedingly simple, as does "all records that are different from the previous one on this field".
Comments
kdb+ has a variant of SQL which is an evolution (not a revolution). The advances basically fall into three categories:
1. Shortcuts, such as "foreign key chasing" - i.e., if "a" int table x is a reference to field b in table y then "a.c" is "select c from x inner join y on (x.a=y.b)"; If you have a star schema, it cuts down queries and errors by 90% (and makes life simple for the optimizer). Of course, you can chase through as many tables as you wish in an expression, making item tables look a lot more like records.
2. Embracing order; The relational model has no ordering among tuples; SQL mostly pretends that's the case, but the order does emerge through "ORDER BY / TOP" and "ROWID" but not very usefully so. kdb+ embraces order and makes e.g. "first record that ..." very simple and intuitive (and also easier for the optimizer).
3. Embracing time series (not independent from embracing order) - when you have e.g. records with a "from .. to" validity range, it becomes exceedingly simple, as does "all records that are different from the previous one on this field".