Subject Re: [firebird-support] Quick search on large Varchar?
Author Bjoern Reimer

HB> The reason this query won't use the index is that the second search
HB> condition requires an unindexed read. By including it, you are obviating
HB> the usefulness of the proxy search column you have set up. It is
HB> redundantly reading both columns when USERS.DN alone would find it in an
HB> unindexed read.

Yes, I thought that. But could a subselect work?

HB> Could you take the company portion of USERS.DN and make a second search
HB> column? Then a compound index on the two columns in the correct
HB> left-to-right order would be used.
No, not realy. The company part includes office etc. and ist up to
2000 chars long.
So I'd to build up to 24 index-columns?

HB> My other comment is that you are forcing extra cycles on this query by
HB> calling a server-side function to pre-process the search parameter. Have
HB> your application process the input string to extract the (two) search
HB> parameters and pass them "ready-to-roll".

I fear I don't understand exactly what you mean with this.