[SQL] BITMAP INDEXES...
Hi, I have learnt from certain texts that bitmap indexes are very useful for large DSS (decesion support systems). bitmap indexes are currently not available in postgresql. My question is in what way is a normal btree index in pgsql inferior to bitmap indexes (found in oracle for example). is it just in terms of space requirements for performance too? regds mallah. -- Rajesh Kumar Mallah, Project Manager (Development) Infocom Network Limited, New Delhi phone: +91(11)6152172 (221) (L) ,9811255597 (M) Visit http://www.trade-india.com , India's Leading B2B eMarketplace. ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
[SQL] Separating data sets in a table
Hello, I want to solve the following problem: CREATE TABLE Ref( Id int ) ; CREATE TABLE Import ( Idint, Other varchar(42), Flag int, Tstimestamp ) ; CREATE TABLE Data ( Idint, Other varchar(42) ) ; The table Import will be filled by a COPY FROM statement and contains no checks for referential integrity. The columns Id and Other have to be moved to the table Data if the table Ref contains the Id. If not Flag should get a certain value that something went wrong. Moreover Import should only contain one representation of a dataset with equal Id and Other column and I would like to store the newest one (this is the reason for the timestamp). I tried to do the following approach: CREATE LOCAL TEMPORARY TABLE ImportOK () INHERITS (Import) ; INSERT INTO ImportOK SELECT * FROM Import i INNER JOIN Ref r ON i.Id = r.Id; DELETE FROM Import WHERE Id IN (SELECT Id FROM ImportOK) ; The idea was that the latest statement should get rid of all valid data sets from Import. The valid datasets now could be moved to Data and I could afterwards check Import for duplicated data sets. Unfortunately the latest statement is so terribly slow that I can't imagine that there is a better way to do this. It seems like a very beginner question but I have no real clue how to do this right. Probably the solution has to be done completely different. Thanks for your patience Andreas. ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
Re: [SQL] Problem with timestamp field/time function.. (upgrading
Hi Stephan
>> So, how can I get the same result above without using time() ??
>>Or if it not possible, how can I extract (yes, I tried with extract()
>>function too) time from a timestamp column?
>> I know it's quite simple question... but I haven't find any clue!
>>
>
> In general you could probably use CAST(materiadata as time) I'd guess.
> I believe that at this point you can still use the functions, you just
> need to double quote them ("time"(materiadata)) to differentiate them
> from the type specifiers.
>
Well, it seems to work only with "timestamp without time zone" type. But
worked. Thanks a lot.
For me it's a new approching not using functions such as time, but
"casting" it to a "time" type ( like select materiadata::time from
materia;).
If PostgreSQL development group change it's point of view, I suppose
there's some advantage. Do you know some advantages ??
bests regards
--
[]'s
Lucas Brasilino
[EMAIL PROTECTED]
http://www.recife.pe.gov.br
Emprel -Empresa Municipal de Informatica (pt_BR)
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Recife - Pernambuco - Brasil
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[SQL] bytea etc.
Hi , All!
Could someone clarify me :
When I want to store BLOB's internally in database (for example jpeg )
should I use bytea or OID? Is OID something like BFILE in Oracle 8i?
If both are appropriate for internal BLOB why I can't use
update image set picture=lo_import('Myfile') where image_code='blablabla' ;
with bytea column type but only with OID column type?
And one more thing:
Where is function byteain documented?
TIA,
Andrew.Do You Yahoo!?
HotJobs, a Yahoo! service - Search Thousands of New Jobs
Re: [SQL] Problem with timestamp field/time function.. (upgrading
On Thu, 22 Aug 2002, Lucas Brasilino wrote:
> Hi Stephan
>
> >>So, how can I get the same result above without using time() ??
> >>Or if it not possible, how can I extract (yes, I tried with extract()
> >>function too) time from a timestamp column?
> >>I know it's quite simple question... but I haven't find any clue!
> >>
> >
> > In general you could probably use CAST(materiadata as time) I'd guess.
> > I believe that at this point you can still use the functions, you just
> > need to double quote them ("time"(materiadata)) to differentiate them
> > from the type specifiers.
> >
>
> Well, it seems to work only with "timestamp without time zone" type. But
> worked. Thanks a lot.
> For me it's a new approching not using functions such as time, but
> "casting" it to a "time" type ( like select materiadata::time from
> materia;).
> If PostgreSQL development group change it's point of view, I suppose
> there's some advantage. Do you know some advantages ??
time(n) and timestamp(n) refer to a type which I believe gives n digits of
fractional seconds in SQL. Compatibility for that SQL feature was added
but the syntax collided with the old usage. In any case the old time()
etc were actually typecasts since it was a direct call to the type casting
function.
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Re: [SQL] BITMAP INDEXES...
See the email about bitmapped indexes linked to from the TODO list item on bitmaps. Bitmap indexes allow arbitrary indexes to be combined into a single index. Btree indexes can not be combined. --- Rajesh Kumar Mallah. wrote: > Hi, > > I have learnt from certain texts that bitmap indexes are very useful for > large DSS (decesion support systems). > > bitmap indexes are currently not available in postgresql. > > My question is in what way is a normal btree index in pgsql > inferior to bitmap indexes (found in oracle for example). > > is it just in terms of space requirements for performance too? > > > regds > mallah. > > > -- > Rajesh Kumar Mallah, > Project Manager (Development) > Infocom Network Limited, New Delhi > phone: +91(11)6152172 (221) (L) ,9811255597 (M) > > Visit http://www.trade-india.com , > India's Leading B2B eMarketplace. > > > > ---(end of broadcast)--- > TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED]) > -- Bruce Momjian| http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup.| Newtown Square, Pennsylvania 19073 ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
