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  1. Redis 16 times faster than Postgres?

    Colin 't Hart <colinthart@gmail.com> — 2019-09-29T21:42:00Z

    Hi,

Can someone take a look at this blog post?
https://www.peterbe.com/plog/redis-vs-postgres-blob-of-json

Can Redis really be 16 times faster than Postgres? Surely Postgres can get
closer to the raw speed of the hardware than 1 order of magnitude?

Thanks,

Colin

  2. Re: Redis 16 times faster than Postgres?

    Nathan Woodrow <madmanwoo@gmail.com> — 2019-09-29T21:46:14Z

    Redis is a in memory database so I would except it to be always much
faster..

On Mon., 30 Sep. 2019, 7:42 am Colin 't Hart, <colinthart@gmail.com> wrote:

> Hi,
>
> Can someone take a look at this blog post?
> https://www.peterbe.com/plog/redis-vs-postgres-blob-of-json
>
> Can Redis really be 16 times faster than Postgres? Surely Postgres can get
> closer to the raw speed of the hardware than 1 order of magnitude?
>
> Thanks,
>
> Colin
>

  3. Re: Redis 16 times faster than Postgres?

    Ron Johnson <ronljohnsonjr@gmail.com> — 2019-09-29T21:52:15Z

    On 9/29/19 4:42 PM, Colin 't Hart wrote:
> Hi,
>
> Can someone take a look at this blog post?
> https://www.peterbe.com/plog/redis-vs-postgres-blob-of-json
>
> Can Redis really be 16 times faster than Postgres? Surely Postgres can get 
> closer to the raw speed of the hardware than 1 order of magnitude?

Redis is an in-memory key-value database. PostgreSQL... isn't.


-- 
Angular momentum makes the world go 'round.

  4. Re: Redis 16 times faster than Postgres?

    Morris de Oryx <morrisdeoryx@gmail.com> — 2019-09-30T00:01:46Z

    Sigh. I despair of "16x faster" and "20x faster" headlines that ignore the
raw numbers. *The worst numbers in there are far below the threshold of
user perception*. Unless these results are compounded by running in a loop,
they are meaningless. Not immeasurable, just meaningless.

https://www.nngroup.com/articles/response-times-3-important-limits/

That piece is from 1993, but the human nervous system hasn't changed since
then.

  5. Re: Redis 16 times faster than Postgres?

    Ron Johnson <ronljohnsonjr@gmail.com> — 2019-09-30T00:25:27Z

    On 9/29/19 7:01 PM, Morris de Oryx wrote:
> Sigh. I despair of "16x faster" and "20x faster" headlines that ignore the 
> raw numbers. *The worst numbers in there are far below the threshold of 
> user perception*. Unless these results are compounded by running in a 
> loop, they are meaningless. Not immeasurable, just meaningless.
>
> https://www.nngroup.com/articles/response-times-3-important-limits/
>
> That piece is from 1993, but the human nervous system hasn't changed since 
> then.

Back-end web servers don't have human nervous systems. Faster response time 
means that a give bit of hardware can support a much higher load, saving you 
money

-- 
Angular momentum makes the world go 'round.

  6. Re: Redis 16 times faster than Postgres?

    Morris de Oryx <morrisdeoryx@gmail.com> — 2019-09-30T00:59:20Z

    > Back-end web servers don't have human nervous systems. Faster response
time means that a give bit of hardware can support
>  a much higher load, saving you money

Fair point, I can't argue against it as stated. Although I have no way of
know if this person's site is *ever* overloaded or has any chance of saving
money. Other sites do for sure. Not knocking using in-memory caches, they
can be a life-saver.

Like everyone else here, I've been to a *lot* of meetings down the year
that came down to arguing about optimizations that could not pay for
themselves before the heat death of the universe. As such, I've developed
an allergy to context-free performance comparisons.

On Mon, Sep 30, 2019 at 10:25 AM Ron <ronljohnsonjr@gmail.com> wrote:

> On 9/29/19 7:01 PM, Morris de Oryx wrote:
>
> Sigh. I despair of "16x faster" and "20x faster" headlines that ignore the
> raw numbers. *The worst numbers in there are far below the threshold of
> user perception*. Unless these results are compounded by running in a
> loop, they are meaningless. Not immeasurable, just meaningless.
>
> https://www.nngroup.com/articles/response-times-3-important-limits/
>
> That piece is from 1993, but the human nervous system hasn't changed since
> then.
>
>
> Back-end web servers don't have human nervous systems. Faster response
> time means that a give bit of hardware can support a much higher load,
> saving you money
>
> --
> Angular momentum makes the world go 'round.
>

  7. Re: Redis 16 times faster than Postgres?

    Steve Litt <slitt@troubleshooters.com> — 2019-09-30T01:09:52Z

    On Mon, 30 Sep 2019 07:46:14 +1000
Nathan Woodrow <madmanwoo@gmail.com> wrote:

> Redis is a in memory database so I would except it to be always much
> faster..

Is there a way to have Redis periodically update an on-disk backup?
That would be great, but otherwise you're at the mercy of your power
company (here in Central Florida it's routine for power to go down and
stay down for five hours).

SteveT
 
Steve Litt
Author: The Key to Everyday Excellence
http://www.troubleshooters.com/key
Twitter: http://www.twitter.com/stevelitt

  8. Re: Redis 16 times faster than Postgres?

    raf <raf@raf.org> — 2019-09-30T03:05:55Z

    Steve Litt wrote:

> On Mon, 30 Sep 2019 07:46:14 +1000
> Nathan Woodrow <madmanwoo@gmail.com> wrote:
> 
> > Redis is a in memory database so I would except it to be always much
> > faster..
> 
> Is there a way to have Redis periodically update an on-disk backup?
> That would be great, but otherwise you're at the mercy of your power
> company (here in Central Florida it's routine for power to go down and
> stay down for five hours).
> 
> SteveT
>  
> Steve Litt
> Author: The Key to Everyday Excellence
> http://www.troubleshooters.com/key
> Twitter: http://www.twitter.com/stevelitt

i don't know but voltdb, another in-memory database,
replicates to other instances which can be in different
geographical locations and so not prone to a single
power failure. perhaps all in-memory databases are
aware of the need for this.

cheers,
raf

  9. Re: Redis 16 times faster than Postgres?

    Ron Johnson <ronljohnsonjr@gmail.com> — 2019-09-30T03:44:13Z

    On 9/29/19 8:09 PM, Steve Litt wrote:
> On Mon, 30 Sep 2019 07:46:14 +1000
> Nathan Woodrow <madmanwoo@gmail.com> wrote:
>
>> Redis is a in memory database so I would except it to be always much
>> faster..
> Is there a way to have Redis periodically update an on-disk backup?
> That would be great, but otherwise you're at the mercy of your power
> company (here in Central Florida it's routine for power to go down and
> stay down for five hours).

It would be criminal for it not to have an async writer process flushing 
modified pages to disk.  And to not have a UPS that you've tested.

-- 
Angular momentum makes the world go 'round.

  10. Re: Redis 16 times faster than Postgres?

    Michael Paquier <michael@paquier.xyz> — 2019-09-30T03:48:10Z

    On Sun, Sep 29, 2019 at 04:52:15PM -0500, Ron wrote:
> On 9/29/19 4:42 PM, Colin 't Hart wrote:
> Redis is an in-memory key-value database. PostgreSQL... isn't.

Well, I think that you have never heard about the urban legend of
running Postgres on scissors then and this reminds me of this blog
post:
http://www.databasesoup.com/2015/02/running-with-scissors-mode.html

Note that sometimes I have run Postgres on a tmpfs as well to test
some specific patches.  So that can be done, and of course that's
unsafe.
--
Michael

  11. Re: Redis 16 times faster than Postgres?

    Ben Chobot <bench@silentmedia.com> — 2019-09-30T03:52:10Z

    On Sep 29, 2019, at 8:44 PM, Ron <ronljohnsonjr@gmail.com> wrote:
> 
> On 9/29/19 8:09 PM, Steve Litt wrote:
>> On Mon, 30 Sep 2019 07:46:14 +1000
>> Nathan Woodrow <madmanwoo@gmail.com> wrote:
>> 
>>> Redis is a in memory database so I would except it to be always much
>>> faster..
>> Is there a way to have Redis periodically update an on-disk backup?
>> That would be great, but otherwise you're at the mercy of your power
>> company (here in Central Florida it's routine for power to go down and
>> stay down for five hours).
> 
> It would be criminal for it not to have an async writer process flushing modified pages to disk.  And to not have a UPS that you've tested.

It's perfectly reasonable to use Redis as a caching layer without any persistence at all. In such cases, flushing state to disk is a waste of resources. 

(For other use cases, yes, Redis allows you to flush state to disk.)

  12. Re: Redis 16 times faster than Postgres?

    Imre Samu <pella.samu@gmail.com> — 2019-09-30T09:40:31Z

    from the original article:
> For example, the PostgreSQL speeds depend on the Django ORM code
> that makes the SQL and sends the query and then turns it into the model
instance.
> I don't know what the proportions are between that and
> the actual bytes-from-PG's-disk times. But I'm not sure I care either.

imho:   the "Django ORM" is not so fast.
according to "TechEmpower Web Framework Benchmarks" ...
it has only  ~3% performance  -  compare to the best rust+pg (100%) results.

example:
"Data updates"
https://www.techempower.com/benchmarks/#section=data-r18&hw=ph&test=update
the "django-postgresql" performance = 766   - only 3.0% of the best pg +
rust results
checking the other test types (  "Single query" ;" Multiple queries" ) has
a similar results.

the Django implementation of the test:
https://github.com/TechEmpower/FrameworkBenchmarks/tree/master/frameworks/Python/django

Imre


Colin 't Hart <colinthart@gmail.com> ezt írta (időpont: 2019. szept. 29.,
V, 23:42):

> Hi,
>
> Can someone take a look at this blog post?
> https://www.peterbe.com/plog/redis-vs-postgres-blob-of-json
>
> Can Redis really be 16 times faster than Postgres? Surely Postgres can get
> closer to the raw speed of the hardware than 1 order of magnitude?
>
> Thanks,
>
> Colin
>