Re: Locking B-tree leafs immediately in exclusive mode

On Thu, Jun 14, 2018 at 4:56 PM Claudio Freire <klaussfreire@gmail.com> wrote:
> Not at all. Insertion cost in unique indexes with lots of duplicates
> (happens, dead duplicates) grows quadratically on the number of
> duplicates, and that's improved by making the index unique and sorted.

Sorry, I've messed up the terms.  I did actually compare current
non-unique indexes with non-unique indexes keeping duplicate entries
ordered by TID (which makes them somewhat unique).  I didn't really
considered indexes, which forces unique constraints.  For them
insertion cost grows quadratically (as you mentioned) independently on
whether we're keeping duplicates ordered by TID or not.

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Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company