Craig James wrote: > 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.
What would happen when you inserted a new tuple with just "miss"? You would need to expand all the other tuples in the index. -- Alvaro Herrera http://www.flickr.com/photos/alvherre/ "Puedes vivir solo una vez, pero si lo haces bien, una vez es suficiente" ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
