Numeric Operators in SQL Where clauses
On Fri, Feb 2, 2018 at 4:50 PM, Das Goravani <email@example.com> wrote:
> > On Feb 2, 2018, at 1:35 PM, Clifford Ilkay <firstname.lastname@example.org> wrote:
> > You should be aware that if you have large datasets and you’re doing a
> > on a low-cardinality (lots of similar or same data) column, the query
> > do a table scan (evaluate all rows) and performance will suffer.
> Is this true even if the column’s searched with ‘LIKE’ are indexed?
It depends on the type of index. This fellow does a good job of explaining.
<niallburkley.com/blog/index-columns-for-like-in-postgres/> Much of
this is going to depend on the nature of your data. If you don’t know yet,
don’t worry about it. Premature optimization is the enemy of good.
As for your “generic SQL” question, as Alex pointed out, there is no such
thing. There will be differences and those differences can range from
trivial to “you can’t get there from here”. You will always have this
tension between portability, performance, productivity, and robustness. You
can’t have all of those things at the same time.