On Thu, Aug 8, 2013 at 5:01 PM, Kevin Grittner wrote:
> Claudio Freire wrote:
>> On Wed, Aug 7, 2013 at 4:04 PM, Tom Lane wrote:
Yeah, but it's faster if it's in the same direction, because the
kernel read-ahead code detects sequential reads, whereas it doesn't
when it goes backwa
On Wed, Aug 7, 2013 at 4:04 PM, Tom Lane wrote:
>> Yeah, but it's faster if it's in the same direction, because the
>> kernel read-ahead code detects sequential reads, whereas it doesn't
>> when it goes backwards. The difference can be up to a factor of 10 for
>> long index scans.
>
> Color me ske
Claudio Freire escribió:
> On Wed, Aug 7, 2013 at 3:34 PM, Tom Lane wrote:
> > Note that there's no particular need to specify "desc" in the index
> > definition. This same index can support searches in either direction
> > on the "called" column.
>
> Yeah, but it's faster if it's in the same d
Claudio Freire writes:
> On Wed, Aug 7, 2013 at 3:34 PM, Tom Lane wrote:
>> Note that there's no particular need to specify "desc" in the index
>> definition. This same index can support searches in either direction
>> on the "called" column.
> Yeah, but it's faster if it's in the same directio
On Wed, Aug 7, 2013 at 3:34 PM, Tom Lane wrote:
> Claudio Freire writes:
>> On Wed, Aug 7, 2013 at 3:12 PM, Robert DiFalco
>> wrote:
>>> I want to get the last call_activity record for a single user.
>
>> Create an index over (user_id, called desc), and do
>> select * from call_activity where u
M
> > To: Robert DiFalco
> > Cc: pgsql-performance@postgresql.org
> > Subject: Re: [PERFORM] Efficiently query for the most recent record for a
> > given user
> >
> > On Wed, Aug 7, 2013 at 3:12 PM, Robert DiFalco >
> > wrote:
> > > Let'
[PERFORM] Efficiently query for the most recent record for a
> given user
>
> On Wed, Aug 7, 2013 at 3:12 PM, Robert DiFalco
> wrote:
> > Let's say I have a table something like this:
> >
> >create table call_activity (
> > id int8 not null,
&
Claudio Freire writes:
> On Wed, Aug 7, 2013 at 3:12 PM, Robert DiFalco
> wrote:
>> I want to get the last call_activity record for a single user.
> Create an index over (user_id, called desc), and do
> select * from call_activity where user_id = blarg order by called desc limit 1
Note that th
On Wed, Aug 7, 2013 at 3:12 PM, Robert DiFalco wrote:
> Let's say I have a table something like this:
>
>create table call_activity (
> id int8 not null,
> called timestamp,
> user_id int8 not null,
> primary key (id)
> foreign key (user_id) references m
Let's say I have a table something like this:
create table call_activity (
id int8 not null,
called timestamp,
user_id int8 not null,
primary key (id)
foreign key (user_id) references my_users
)
I want to get the last call_activity record for a sing
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