Re: LIKE search and performance

Mark Lewis wrote:

> PG could scan the index looking for matches first and only load the
> actual rows if it found a match, but that could only be a possible win
> if there were very few matches, because the difference in cost between a
> full index scan and a sequential scan would need to be greater than the
> cost of randomly fetching all of the matching data rows from the table
> to look up the visibility information.

Just out of curiosity: Does Postgress store a duplicate of the data in the index, even for long strings? I thought indexes only had to store the string up to the point where there was no ambiguity, for example, if I have "missing", "mississippi" and "misty", the index only needs "missin", "missis" and "mist" in the actual index. This would make it impossible to use a full index scan for a LIKE query.

Craig