Thread: index on an int8 column
I have a table with a column of type int8. When I try to create an
index on it, the
database protests and gives the following error message:
ERROR: Can't find a default operator class for type 20.
Is there an easy fix for this? I assumed builtin numeric types would
have
default comparison functions.
Also, if I am not posting to the appropriate mailing list, please let me
know.
Thanks in advance,
Sarah Officer
officers@aries.tucson.saic.com
It works on 6.5beta1. Sarah Officer ha scritto: > I have a table with a column of type int8. When I try to create an > index on it, the > database protests and gives the following error message: > > ERROR: Can't find a default operator class for type 20. > > Is there an easy fix for this? I assumed builtin numeric types would > have > default comparison functions. > > Also, if I am not posting to the appropriate mailing list, please let me > know. > > Thanks in advance, > > Sarah Officer > officers@aries.tucson.saic.com ______________________________________________________________ PostgreSQL 6.5.0 on i586-pc-linux-gnu, compiled by gcc 2.7.2.3 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Jose'
This is probably one of those things everyone knows except me, but my search of the documentation only turned up it's not a keyword in PostgreSQL... SELECT * FROM foo WHERE ROW_COUNT < 10; Is there anything like "ROW_COUNT" or "ROWCOUNT" in PostgreSQL? I've been looking through "The Practical SQL Handbook" as I know it is a significant influence on PostgreSQL, and I haven't found anything similar there either. Bruce Tong | Got me an office; I'm there late at night. Systems Programmer | Just send me e-mail, maybe I'll write. Electronic Vision / FITNE | zztong@laxmi.ev.net | -- Joe Walsh for the 21st Century
Try "select count(*) from row" to get a count of the number of rows. If trying to receive 10 rows, try begin; declare thomas cursor for select * from foo; fetch 10 in thomas; end; Bruce Tong wrote: > > This is probably one of those things everyone knows except me, but my > search of the documentation only turned up it's not a keyword in > PostgreSQL... > > SELECT * FROM foo WHERE ROW_COUNT < 10; > > Is there anything like "ROW_COUNT" or "ROWCOUNT" in PostgreSQL? > > I've been looking through "The Practical SQL Handbook" as I know it is a > significant influence on PostgreSQL, and I haven't found anything similar > there either. > > Bruce Tong | Got me an office; I'm there late at night. > Systems Programmer | Just send me e-mail, maybe I'll write. > Electronic Vision / FITNE | > zztong@laxmi.ev.net | -- Joe Walsh for the 21st Century -- ------------------------------------------------------------ Thomas Reinke Tel: (416) 460-7021 Director of Technology Fax: (416) 598-2319 E-Soft Inc. http://www.e-softinc.com
> > SELECT * FROM foo WHERE ROW_COUNT < 10; > > Is there anything like "ROW_COUNT" or "ROWCOUNT" in PostgreSQL? > If trying to receive 10 rows, try > > begin; > declare thomas cursor for select * from foo; > fetch 10 in thomas; > end; Ooo, a cursor. I'll have to look into those. I was thinking I could just issue "select * from foo" and then only use the first 10 results, but that seemed like such a waste of time since there's likely to be 100's of records. Admittedly I'm ignorant of the solution you pose and I'll have to do some research, but it seems it too might also have the postmaster return all of the records, of which I would only use 10. Am I wrong? Bruce Tong | Got me an office; I'm there late at night. Systems Programmer | Just send me e-mail, maybe I'll write. Electronic Vision / FITNE | zztong@laxmi.ev.net | -- Joe Walsh for the 21st Century
Bruce Tong wrote:
>
> > > SELECT * FROM foo WHERE ROW_COUNT < 10;
> > > Is there anything like "ROW_COUNT" or "ROWCOUNT" in PostgreSQL?
>
> > If trying to receive 10 rows, try
> >
> > begin;
> > declare thomas cursor for select * from foo;
> > fetch 10 in thomas;
> > end;
>
> Ooo, a cursor. I'll have to look into those. I was thinking I could just
> issue "select * from foo" and then only use the first 10 results, but that
> seemed like such a waste of time since there's likely to be 100's of
> records. Admittedly I'm ignorant of the solution you pose and I'll have to
> do some research, but it seems it too might also have the postmaster
> return all of the records, of which I would only use 10. Am I wrong?
Yes. It is designed explicitly for the purpose of limiting the returns.
For example, if you have a database of several million records and
want only 10 to be returned...
For example, a piece of code that wanted to be conservative on memory
usage, while handling millions of records in the database, might issue
(pseudo-code):
begin;
declare thomas cursor for select * from foo;
do
res = fetch 10 in thomas;
iRows = nTuples(res)
process_records;
while(iRows>0);
end;
From a coding perspective, you deal with the results of the fetch just
as if they had come from the select.
Hope this helps
Thomas
>
> Bruce Tong | Got me an office; I'm there late at night.
> Systems Programmer | Just send me e-mail, maybe I'll write.
> Electronic Vision / FITNE |
> zztong@laxmi.ev.net | -- Joe Walsh for the 21st Century
--
------------------------------------------------------------
Thomas Reinke Tel: (416) 460-7021
Director of Technology Fax: (416) 598-2319
E-Soft Inc. http://www.e-softinc.com
On Wed, 5 May 1999, Bruce Tong wrote:
Someone has a table with a column named row_count.
# This is probably one of those things everyone knows except me, but my
# search of the documentation only turned up it's not a keyword in
# PostgreSQL...
#
# SELECT * FROM foo WHERE ROW_COUNT < 10;
#
# Is there anything like "ROW_COUNT" or "ROWCOUNT" in PostgreSQL?
#
# I've been looking through "The Practical SQL Handbook" as I know it is a
# significant influence on PostgreSQL, and I haven't found anything similar
# there either.
#
#
# Bruce Tong | Got me an office; I'm there late at night.
# Systems Programmer | Just send me e-mail, maybe I'll write.
# Electronic Vision / FITNE |
# zztong@laxmi.ev.net | -- Joe Walsh for the 21st Century
#
#
#
#
--
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pub 1024/3CAE01D5 1994/11/03 Dustin Sallings <dustin@spy.net>
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