Re: Postgres 9.6 scariest patch tournament

Noah Misch wrote:
> On Mon, Apr 18, 2016 at 03:37:21PM -0300, Alvaro Herrera wrote:
> > The RMT will publish aggregate, unattributed results after the poll
> > closes.

Here are some more detailed results. We got 15 valid replies. One
person voted twice, mentioning the same patches both times in slightly
different order; I considered the second reply only.

"Parallel Query" got many mentions; some of them were specific commits
(such as "parallel infrastructure", "parallel joins", "parallel
aggregates") and others were more generic. For the generic mentions I
just chose a few of the most salient patches, but didn't include either
parallel aggregates nor parallel joins in that list. "LWLock tranches"
and "Freeze Map" also resulted in several commits appearing in the list
below. This distorts the results somewhat. I considered redoing the
results once I noticed the problem, but didn't really want to invest
*too* much time.

I chose to ignore the scariness rating in this tabular report.

┌───────┬──────────────────────────────────────────┬─────────────────────────┬─────────────────────────────────────────────────────────────────────────────┐
│ count │ sha1 │ committer │ subject │
├───────┼──────────────────────────────────────────┼─────────────────────────┼─────────────────────────────────────────────────────────────────────────────┤
│ 8 │ fd31cd265138019dcccc9b5fe53043670898bc9f │ rhaas(at)postgresql(dot)org │ Don't vacuum all-frozen pages. │
│ 6 │ 924bcf4f16d54c55310b28f77686608684734f42 │ rhaas(at)postgresql(dot)org │ Create an infrastructure for parallel computation in PostgreSQL. │
│ 5 │ f0661c4e8c44c0ec7acd4ea7c82e85b265447398 │ rhaas(at)postgresql(dot)org │ Make sequential scans parallel-aware. │
│ 5 │ ee7ca559fcf404f9a3bd99da85c8f4ea9fbc2e92 │ rhaas(at)postgresql(dot)org │ Add a C API for parallel heap scans. │
│ 3 │ a892234f830e832110f63fc0a2afce2fb21d1584 │ rhaas(at)postgresql(dot)org │ Change the format of the VM fork to add a second bit per page. │
│ 3 │ 3fc6e2d7f5b652b417fa6937c34de2438d60fa9f │ tgl(at)sss(dot)pgh(dot)pa(dot)us │ Make the upper part of the planner work by generating and comparing Paths. │
│ 3 │ 848ef42bb8c7909c9d7baa38178d4a209906e7c1 │ kgrittn(at)postgresql(dot)org │ Add the "snapshot too old" feature │
│ 2 │ bb140506df605fab58f48926ee1db1f80bdafb59 │ teodor(at)sigaev(dot)ru │ Phrase full text search. │
│ 2 │ 9cd00c457e6a1ebb984167ac556a9961812a683c │ andres(at)anarazel(dot)de │ Checkpoint sorting and balancing. │
│ 1 │ 3bd909b220930f21d6e15833a17947be749e7fde │ rhaas(at)postgresql(dot)org │ Add a Gather executor node. │
│ 1 │ c319991bcad02a2e99ddac3f42762b0f6fa8d52a │ rhaas(at)postgresql(dot)org │ Use separate lwlock tranches for buffer, lock, and predicate lock managers. │
│ 1 │ 1c1a7cbd6a1600c97dfcd9b5dc78a23b5db9bbf6 │ tgl(at)sss(dot)pgh(dot)pa(dot)us │ Sync our copy of the timezone library with IANA release tzcode2016c. │
│ 1 │ 65578341af1ae50e52e0f45e691ce88ad5a1b9b1 │ teodor(at)sigaev(dot)ru │ Add Generic WAL interface │
│ 1 │ c09b18f21c52cbcf8718d6c267c84fcfea3739a9 │ alvherre(at)alvh(dot)no-ip(dot)org │ Support crosstabview in psql │
│ 1 │ e4106b2528727c4b48639c0e12bf2f70a766b910 │ rhaas(at)postgresql(dot)org │ postgres_fdw: Push down joins to remote servers. │
│ 1 │ 428b1d6b29ca599c5700d4bc4f4ce4c5880369bf │ andres(at)anarazel(dot)de │ Allow to trigger kernel writeback after a configurable number of writes. │
│ 1 │ 6150a1b08a9fe7ead2b25240be46dddeae9d98e1 │ rhaas(at)postgresql(dot)org │ Move buffer I/O and content LWLocks out of the main tranche. │
│ 1 │ 48354581a49c30f5757c203415aa8412d85b0f70 │ andres(at)anarazel(dot)de │ Allow Pin/UnpinBuffer to operate in a lockfree manner. │
│ 1 │ 7a542700df25eaf97b794bff63606176433dcdda │ sfrost(at)snowman(dot)net │ Create default roles │
│ 1 │ 013ebc0a7b7ea9c1b1ab7a3d4dd75ea121ea8ba7 │ teodor(at)sigaev(dot)ru │ Microvacuum for GIST │
│ 1 │ 53be0b1add7064ca5db3cd884302dfc3268d884e │ rhaas(at)postgresql(dot)org │ Provide much better wait information in pg_stat_activity. │
│ 1 │ 0711803775a37e0bf39d7efdd1e34d9d7e640ea1 │ rhaas(at)postgresql(dot)org │ Use quicksort, not replacement selection, for external sorting. │
│ 1 │ b319356f0e94a6482c726cf4af96597c211d8d6e │ rhaas(at)postgresql(dot)org │ Migrate PGPROC's backendLock into PGPROC itself, using a new tranche. │
│ 1 │ 11c8669c0cc7abc7a7702594cf13452c378d2517 │ rhaas(at)postgresql(dot)org │ Add parallel query support functions for assorted aggregates. │
│ 1 │ 2251179e6ad3a865d2f55e1832fab34608fcce43 │ rhaas(at)postgresql(dot)org │ Migrate replication slot I/O locks into a separate tranche. │
│ 1 │ 45be99f8cd5d606086e0a458c9c72910ba8a613d │ rhaas(at)postgresql(dot)org │ Support parallel joins, and make related improvements. │
│ 1 │ 7117685461af50f50c03f43e6a622284c8d54694 │ magnus(at)hagander(dot)net │ Implement backup API functions for non-exclusive backups │
│ 1 │ 98a64d0bd713cb89e61bef6432befc4b7b5da59e │ andres(at)anarazel(dot)de │ Introduce WaitEventSet API. │
└───────┴──────────────────────────────────────────┴─────────────────────────┴─────────────────────────────────────────────────────────────────────────────┘

It's clear that Robert is winner, even if you discount the distortion
caused by counting one entry as multiple patches.

--
Álvaro Herrera