Re: Core Data and indexed attributes question (from a CD noobie)
Re: Core Data and indexed attributes question (from a CD noobie)
- Subject: Re: Core Data and indexed attributes question (from a CD noobie)
- From: "Kyle Sluder" <email@hidden>
- Date: Sat, 8 Mar 2008 14:01:43 -0500
On Sat, Mar 8, 2008 at 1:14 PM, David Hoerl <email@hidden> wrote:
> I cannot find nothing in the Xcode user documentation, the Core Data
> documentation, nor on this list that explain what the "Indexed"
> checkbox in Xcode 3's Attribute panel is for.
>
> A link or short explanation would be helpful. Thanks!
It creates an index on that field. If you've never worked with
databases before, an index is a separate list of the records in a
table, keyed on a certain field(s). It's the same in Core Data; for
each indexed attribute of a type, a list of all the entities of that
type is created and maintained, ordered somehow on that attribute to
make lookups faster. Lots of indexes makes the persistent store
balloon in size, though, so only use them when you can show it leads
to a performance improvement. Things like names, social security
numbers, etc. make good candidates for indexed attributes.
--Kyle Sluder
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