Through googling, i found that Normal Disk has external data transfer rate of
around 40MBps,
^^
Does this includes, seek and rotational latency ?
where as Main Memory has Data transfer rate ra
Anjan,
> But, in PostgreSQL all costs are scaled relative to a page fetch. If we
> make both sequential_page_fetch_cost and random_page_cost to "1", then we
> need to increase the various cpu_* paramters by multiplying the default
> values with appropriate Scaling Factor. Now, we need to dete
On Mon, Dec 12, 2005 at 06:39:42PM +0530, Anjan Kumar. A. wrote:
> Through googling, i found that Normal Disk has external data transfer rate
> of around 40MBps,
> where as Main Memory has Data transfer rate ranging from 1.6GBps to 2.8GBps.
I think 40MB/s is a burst speed. You should do some test
Defaulat values of various parameters in PostgreSQL:
#random_page_cost = 4 # units are one sequential page fetch
cost
#cpu_tuple_cost = 0.01 # (same)
#cpu_index_tuple_cost = 0.001 # (same)
#cpu_operator_cost = 0.0025 # (same)
#e
Am Sonntag, den 11.12.2005, 17:55 -0500 schrieb Carlos Moreno:
...
> I'm interested in adding additional hash functions -- PG supports, as part
> of the built-in SQL functions, MD5 hashing. So, for instance, I can simply
> type, at a psql console, the following:
>
> select md5('abc');
>
> My "fe
Actually, there is probably comparatively little to gain from making it
a builtin. And SHA1 is already there in the pgcrypto contrib module.
Presumably if we wanted a builtin we would start from that code base.
cheers
andrew
Carlos Moreno wrote:
Hi,
I'm very new to this list -- I've bee
Ühel kenal päeval, P, 2005-12-11 kell 17:55, kirjutas Carlos Moreno:
> Hi,
>
> I'm very new to this list -- I've been using and advocating PostgreSQL for
> no less than 4 or 5 years now, and have participated in some of the other
> mailing lists, but never on this one.
>
> My question is (short v
Hi,
I'm very new to this list -- I've been using and advocating PostgreSQL for
no less than 4 or 5 years now, and have participated in some of the other
mailing lists, but never on this one.
My question is (short version): how would one go about adding a new
(built-in) function to PostgreSQL?
Since sequential access is not significantly faster than random access in a
MMDB, random_page_cost will be approximately same as sequential page fetch cost.
As every thing is present in Main Memory, we need to give approximately same
cost to read/write to Main Memory and CPU Related operation
Josh Berkus writes:
> I don't see why you're increasing the various cpu_* costs.
You missed the point Josh --- these numbers are relative to the cost of
a page fetch, so if page fetch is measured in microseconds instead of
milliseconds, then you *do* want to bump the CPU costs up.
Anjan,
> In our case we are reading pages from Main Memory File System, but not from
> Disk. Will it be sufficient, if we change the default values of above
> paramters in "src/include/optimizer/cost.h and
> src/backend/utils/misc/postgresql.conf.sample" as follows:
>
> random_page_cost
I'm working on a project, whose implementation deals with PostgreSQL. A brief
description of the project is given below.
Project Description:
In Main Memory DataBase(MMDB) entire database on the disk is loaded on to
the main memory during initial startup of the sys
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