Even though some databases (MySQL, SQL Server, etc,..), may represent NULL differently. Oracle has always defined NULL as the ABSENCE of a value. That is why "= NULL" and "!= NULL" won't work because nothing = NULL.
Mike
chet justice wrote:As I'm not a real DBA (I only play one on occasion at work), I won't (can't) get into which type of index would be better.However, I do object from a data perspective, to defaulting the inactive rows to NULL. NULL = UNKNOWN correct? In this case, it's not unknown, it's an inactive record. Use 'N' or whatever identifier you choose.Or am I just being a tad obsessive? chetOn Wed, Sep 16, 2009 at 2:56 PM, Toon Koppelaars <toon.koppelaars@xxxxxxxxxxx <mailto:toon.koppelaars@xxxxxxxxxxx>> wrote:Assuming that by far the majority of those rows fall into the "Inactive" category, I think there are a few options:1) Add a nullable column to that table, and put a 'Y' (or whatever) into it to indicate the row is an Active one. Put NULL's in all others. Then create a regular b-tree index on that column for quick access of the Active rows. By not putting 'N' into all the inactive rows, you'll ensure this index is going to remain small (compared to other indexes on that table).2) (assuming there's an PK on that index), create a new table, and only store the PK-values in that table to indicate the ones that are active. So PK of this new-table = PK of the big table. New table has small set of PK's that can be used to drive nested-loops to the big one.3) Variation on 1: *do* put 'N'-s in for the inactive rows, but create a function based index that has no-entries for these rows. Eg. index 'case [column] when 'Y' then 'Y' else null endToonOn Wed, Sep 16, 2009 at 8:43 PM, Steiner, Randy <Randy.Steiner@xxxxxxxx <mailto:Randy.Steiner@xxxxxxxx>> wrote:I have a table with 1 -- 2 million records. I need to add a column to indicate if the records is active or not. I would guess that only 1,000 of the records would not be active. Should I make one of the values null? So I could put a Y or Null? Or put Y or N?Would a b-tree or bitmap index do any good?
