On Mon, Jun 19, 2017 at 4:51 PM, Peter Geoghegan wrote:
> This would make only the first lookup for each distinct value on the
> outer side actually do an index scan on the inner side. I can imagine
> the optimization saving certain queries from consuming a lot of memory
> bandwidth, as well as sa
On Mon, Jun 19, 2017 at 4:35 PM, Andres Freund wrote:
>> I think that this is the way index scan prefetch is normally
>> implemented. Index scans will on average have a much more random
>> access pattern than what is typical for bitmap heap scans, making this
>> optimization more compelling, so ho
On 2017-06-19 15:21:20 -0700, Peter Geoghegan wrote:
> On Mon, Jun 19, 2017 at 8:36 AM, Jeff Janes wrote:
> > Unfortunately, it is only implemented in very narrow circumstances. You
> > have to be doing bitmap index scans of many widely scattered rows to make it
> > useful. I don't think that th
On Mon, Jun 19, 2017 at 3:25 PM, Alvaro Herrera
wrote:
> Surely you could prefetch all the heap pages pointed to by index items
> in the current leaf index page ...
I'm sure that you could do that too. I'm not sure how valuable each
prefetching optimization is.
I can imagine prefetching heap pag
Peter Geoghegan wrote:
> On Mon, Jun 19, 2017 at 8:36 AM, Jeff Janes wrote:
> > Unfortunately, it is only implemented in very narrow circumstances. You
> > have to be doing bitmap index scans of many widely scattered rows to make it
> > useful. I don't think that this is all that common of a sit
On Mon, Jun 19, 2017 at 8:36 AM, Jeff Janes wrote:
> Unfortunately, it is only implemented in very narrow circumstances. You
> have to be doing bitmap index scans of many widely scattered rows to make it
> useful. I don't think that this is all that common of a situation. The
> problem is that
On Mon, Jun 19, 2017 at 10:49:59AM -0500, Merlin Moncure wrote:
> On Mon, Jun 19, 2017 at 10:36 AM, Jeff Janes wrote:
> > If you have a RAID, set it to the number of spindles in your RAID and forget
> > it. It is usually one of the less interesting knobs to play with. (Unless
> > your usage patte
On Mon, Jun 19, 2017 at 8:49 AM, Merlin Moncure wrote:
> On Mon, Jun 19, 2017 at 10:36 AM, Jeff Janes wrote:
> > If you have a RAID, set it to the number of spindles in your RAID and
> forget
> > it. It is usually one of the less interesting knobs to play with.
> (Unless
> > your usage pattern o
On Mon, Jun 19, 2017 at 10:36 AM, Jeff Janes wrote:
> If you have a RAID, set it to the number of spindles in your RAID and forget
> it. It is usually one of the less interesting knobs to play with. (Unless
> your usage pattern of the database is unusual and exact fits the above
> pattern.)
Isn'
On Sun, Jun 18, 2017 at 7:09 PM, David G. Johnston <
david.g.johns...@gmail.com> wrote:
> On Sun, Jun 18, 2017 at 6:02 PM, Patrick B
> wrote:
>
>> Hi guys.
>>
>> I just wanna understand the effective_io_concurrency value better.
>>
>> My current Master database server has 16 vCPUS and I use
>>
Am 19.06.2017 um 03:02 schrieb Patrick B:
Hi guys.
I just wanna understand the effective_io_concurrency value better.
My current Master database server has 16 vCPUS and I
use effective_io_concurrency = 0.
What can be the benefits of increasing that number? Also, do you guys
have any recom
On Sun, Jun 18, 2017 at 6:02 PM, Patrick B wrote:
> Hi guys.
>
> I just wanna understand the effective_io_concurrency value better.
>
> My current Master database server has 16 vCPUS and I use
>
> effective_io_concurrency = 0.
>
It seems as though the number of virtual CPUs little to no bea
*As per the docs:*
*1. This is dependent on whether or not you are using a RAID disk,2. "Some
experimentation may be needed to find the best value"*
*IOW, there is no general recommendation.*
On Sun, Jun 18, 2017 at 9:24 PM, Patrick B wrote:
>
>
> 2017-06-19 13:19 GMT+12:00 Melvin Davidson :
2017-06-19 13:19 GMT+12:00 Melvin Davidson :
>
>
> On Sun, Jun 18, 2017 at 9:02 PM, Patrick B
> wrote:
>
>> Hi guys.
>>
>> I just wanna understand the effective_io_concurrency value better.
>>
>> My current Master database server has 16 vCPUS and I
>> use effective_io_concurrency = 0.
>>
>> What
On Sun, Jun 18, 2017 at 9:02 PM, Patrick B wrote:
> Hi guys.
>
> I just wanna understand the effective_io_concurrency value better.
>
> My current Master database server has 16 vCPUS and I
> use effective_io_concurrency = 0.
>
> What can be the benefits of increasing that number? Also, do you guy
Hi guys.
I just wanna understand the effective_io_concurrency value better.
My current Master database server has 16 vCPUS and I
use effective_io_concurrency = 0.
What can be the benefits of increasing that number? Also, do you guys have
any recommendations?
I'm using PG 9.2 and the official do
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