Hello list, Following from a question I had yesterday, I'm wondering if there is some way to summarize the unique values of an indexed column in PostgreSQL without having the query scan the whole table. For my current work, I have many large tables, all of which have an indexed column for the year from which each row of data was recorded. This year column contains a small number of unique values (e.g., where a large table contains data from one, two or three years...so far). I've been getting the unique values by executing queries like 'select distinct year from [table];', or 'select year from [table] group by year;'. It would seem to me (as I mis-understand it) that if the column is indexed, that the whole table shouldn't need to be queried when all I want to get these values. I figure I should somehow be able to benefit from the index, which presumably knows something about the unique values for this column. Is there some way I can get a list of the unique values directly out of an index? So far, I haven't come across any documentation that suggests this is possible, so I'm guessing there's no straightforward way to do this...can anybody suggest some alternative methods for summarizing the possible values from an indexed column that has a small number of unique values? Thanks in advance, Mike
