Re: B-tree index balance? - Mailing list pgsql-general

From Tom Lane
Subject Re: B-tree index balance?
Date
Msg-id 2630263.1705682238@sss.pgh.pa.us
Whole thread Raw
In response to B-tree index balance?  (Ron Johnson <ronljohnsonjr@gmail.com>)
Responses Re: B-tree index balance?  (Ron Johnson <ronljohnsonjr@gmail.com>)
List pgsql-general
Ron Johnson <ronljohnsonjr@gmail.com> writes:
> On an RDMS which I used in the 1990s and 2000s, b-tree indices of sequences
> would get unbalanced, since every new leaf was added to the far right
> corner of the tree.
> Sure, they would auto-balance *to a degree* during node splits, but all
> those "far-right corner" inserts still left them pretty lopsided.
> Thus, they provided a utility which we could use to determine the
> lopsidedness, and thus decide when to rebuild an index.

> Does Postgresql keep b-tree indexes on sequences fully balanced?  If not,
> how do I see how unbalanced they are?  (Assume PG12+.)

As far as I know, we don't have a problem of that sort.  Continued
insertions will eventually force a split of the root node, which will
rebalance the tree.

            regards, tom lane



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