Re: [HACKERS] Patch: Write Amplification Reduction Method (WARM)

Pavan Deolasee wrote:

> BTW I wanted to share some more numbers from a recent performance test. I
> thought it's important because the latest patch has fully functional chain
> conversion code as well as all WAL-logging related pieces are in place
> too. I ran these tests on a box borrowed from Tomas (thanks!).  This has
> 64GB RAM and 350GB SSD with 1GB on-board RAM. I used the same test setup
> that I used for the first test results reported on this thread i.e. a
> modified pgbench_accounts table with additional columns and additional
> indexes (one index on abalance so that every UPDATE is a potential WARM
> update).
>
> In a test where table + indexes exceeds RAM, running for 8hrs and
> auto-vacuum parameters set such that we get 2-3 autovacuums on the table
> during the test, we see WARM delivering more than 100% TPS as compared to
> master. In this graph, I've plotted a moving average of TPS and the spikes
> that we see coincides with the checkpoints (checkpoint_timeout is set to
> 20mins and max_wal_size large enough to avoid any xlog-based checkpoints).
> The spikes are more prominent on WARM but I guess that's purely because it
> delivers much higher TPS. I haven't shown here but I see WARM updates close
> to 65-70% of the total updates. Also there is significant reduction in WAL
> generated per txn.

Impressive results.  Labels on axes would improve readability of the chart :-)