| From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, "Andrey V(dot) Lepikhov" <a(dot)lepikhov(at)postgrespro(dot)ru> |
| Subject: | Re: Making all nbtree entries unique by having heap TIDs participate in comparisons |
| Date: | 2019-03-12 06:30:22 |
| Message-ID: | 75723f17-dedd-d73f-cdca-61c95ee71293@iki.fi |
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| Lists: | pgsql-hackers |
On 12/03/2019 04:47, Peter Geoghegan wrote:
> In conclusion: I think that this regression is a cost worth accepting.
> The regression in throughput is relatively small (2% - 3%), and the
> NEW_ORDER transaction seems to be the only problem (NEW_ORDER happens
> to be used for 45% of all transactions with TPC-C, and inserts into
> the largest index by far, without reading much). The patch overtakes
> master after a few hours anyway -- the patch will still win after
> about 6 hours, once the database gets big enough, despite all the
> contention. As I said, I think that we see a regression*because* the
> indexes are much smaller, not in spite of the fact that they're
> smaller. The TPC-C/BenchmarkSQL indexes never fail to be about 40%
> smaller than they are on master, no matter the details, even after
> many hours.
Yeah, that's fine. I'm curious, though, could you bloat the indexes back
to the old size by setting the fillfactor?
- Heikki
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