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* Last 'n' records?
@ 1994-09-16 20:50 Bernhard Buettner <root@DL6RAI.MUC.DE>
0 siblings, 1 reply; 2+ messages in thread
From: Bernhard Buettner @ 1994-09-16 20:50 UTC (permalink / raw)
To: legacy
Hello Postgres experts,
I am currently developing amateur radio software utilizig Postgres
with a friend. The application is going to be used as an on-line
database run under packet radio. The database contains data records
which are being entered by many different users and the growth is about
10,000 records/month.
A problem arises with the fact that very often a user wants to
retrieve "the last 'n'" records of the database. Reading through
the manual, I could not find an operator to do this. At this time,
the query is realised as follows:
retrieve portal P unique (data.all) sort by date using >
fetch 5 in P
This will take the whole relation, sort it by date and then retrieve
the last 5 (0.01%). This cannot be the solution, but we can't find
any better. Any hints, ideas?
Greetings,
Ben
--
[] Bernhard Buettner (Ben)
[] Mail: Am Brunnen 18, 85551 Kirchheim, Germany
[] Internet: root@dl6rai.muc.de
[] Packet: DL6RAI @ DB0AAB.#BAY.DEU.EU
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^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Last 'n' records?
@ 1994-09-18 04:20 Robert.Patrick@cs.cmu.edu
parent: Bernhard Buettner <root@DL6RAI.MUC.DE>
0 siblings, 0 replies; 2+ messages in thread
From: Robert.Patrick@cs.cmu.edu @ 1994-09-18 04:20 UTC (permalink / raw)
To: legacy
Excerpts from internet.postgres: 16-Sep-94 Last 'n' records? Bernhard
Buettner@DL6RAI (1441*)
> A problem arises with the fact that very often a user wants to retrieve
> "the last 'n'" records of the database. Reading through the manual, I
> could not find an operator to do this. At this time, the query is
> realised as follows:
> retrieve portal P unique (data.all) sort by date using >
> fetch 5 in P
> This will take the whole relation, sort it by date and then retrieve the
> last 5 (0.01%). This cannot be the solution, but we can't find any
> better. Any hints, ideas?
The only solution (partial solution, anyway) I can see is to specify a
range on the dates so that only records with recent dates will be
retrieved. If you really have 10,000 records/month, try limiting your
query to those records which match today's date (or yesterday's and
today's).
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the subject line ADD or DEL to "postgres-request@postgres.Berkeley.EDU"
If this fails, send mail to "post_questions@postgres.Berkeley.EDU" and
a human will deal with it. DO NOT post to the "postgres" mailing list.
==============================================================================
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