Subject Re: How to "shape" indexes to avoid index depth > 3
Author Dmitry Yemanov
22.01.2019 20:54, Sean Leyne wrote:
> In my database I have some indexes with depth = 4 (db page size is
> already 16KB).
> The indexes are multi-segment, with the fields sequenced from least to
> most selective, and gstat reports a very low selectivity for the index
> (less than 0.00000001).
> The indexed tables have between 100 million and 1500 million (yes, 1.5
> Billion) rows.
> All the FB articles/docs/postings that I have seen have said for
> performance, index depth should be no more than 3.

This is not a hard requirement, 4 levels may be also OK. Are those
multi-segment indices primary/unique keys or just for lookup purposes?