Re: Indexing columns with low cardinality: persistent bitmap indexes?

> > Hello,
> >
> > I have a column with a small number of distinct values, indexing this
one
> > with a standard BTree is useless. How do I can index this column
> > efficiently? I searched and it seems that pg doesn't support the
creation of
> > persistent bitmap indexes... Is that feature planned in next releases of
pg?

> You have a few options based on your access patterns. If you tend to
> access just one of these an get them all at once, then either clusting
> on this value, or partitioning your table will help.

How will clustering benefit this pattern? Won't a full table scan be
required
regardless of the table being clustered? And I thought the point of
clustering
was the organize the table by some indexed key, requiring fewer seeks and
increasing the likelihood of the pages being in the cache .... if the index
is never used in this case ( low cardinality ) would it still help?

> If you access your data using these values and other column values at
> the same time, then partial or multi-column indexes might help.