Subject Re: [Firebird-Architect] Question about limits in fb 2.5 or 3.0
Author Jim Starkey
Dmitry Yemanov wrote:
> Jim Starkey wrote:
>>> Yep, it's already in the tracker and seems quite easy to offer. However,
>>> I foresee some problems for compound indices.
>> What problem? They're implemented in Falcon and it was straightforward.
> It's not a technical problem, more like a support one :-)
> Obviously, you cannot truncate the every segment of the compound index
> before constructing the key, it can be truncated as a whole only. With
> the first segment being long enough, it could mean that other segments
> are not indexed at all (with a performance impact), regardless of the
> user intentions specified in DDL. Not a big problem for sure, just a
> possible confusion.
No, there is no problem truncating segments of a compound key. In fact,
it's the normal case.
> BTW, does Falcon truncate the keys always behind the scene or does it
> offer a custom CREATE INDEX extension for that purpose? We were thinking
> about the latter.
MySQL has syntax in create index for truncated segments. Falcon is
considering doing it automatically in other circumstances, but probably
won't for the first release.

Jim Starkey
President, NimbusDB, Inc.
978 526-1376