[SQL] Table Copy.

[PostgreSQL Server]

HI!

I'm new to postgres. I need to have a table as a copy of another one.

Example:

CREATE TABLE one (
fileda INTEGER,
filedb INTEGER,
filedc INTEGER );

CREATE TABLE two (
fileda INTEGER,
filedb INTEGER,
filedc INTEGER );

As on insert to table one I should get the same insert on table two.
As on delete to table one I should get the same delete on table two.
As on update to table one I should get the same update on table two.

Can someone provide the examples i can study ?

Thanks in advance.

Alex




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[SQL] DATE TIME INDEX ?

[PostgreSQL Server]

I have been tring to use index on timestamps:


I have a table with a timestamp filed with index on it.

I nned to extract all the ids of the table  with datarx 

>= a date
<= a date 

or between 2 dates


I found that the only way to force postgres to use index is:

explain select id,datarx::date from docs where datarx between '2002-11-13' and 
'2002-11-14' ;

Index Scan using idx_documenti_datarx on documenti  (cost=0.00..7.86 rows=2 width=12)

In other cases the index is not used:


explain select id,datarx::date from docs where datarx >= '2002-11-16';
Seq Scan on documenti  (cost=0.00..12.01 rows=107 width=12)

explain select id,datarx::date from docs where datarx::date between '2002-11-13' and 
'2002-11-13' ;
Seq Scan on documenti  (cost=0.00..16.02 rows=36 width=12)

I found that the only way to force postgres to use index is:

explain select id,datarx::date from docs where datarx between '2002-11-13' and 
'2002-11-14' ;
Index Scan using idx_documenti_datarx on documenti  (cost=0.00..7.86 rows=2 width=12)




Do I need to use some other functons o trick?

Thanks in advance

Alex



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[SQL] INDEX PROBLEMS ?

[PostgreSQL Server]

On postgres 7.2.3 I have found what follows:

explain select * from documents where iddoc>1;

Seq Scan on lotti  (cost=0.00..831.79 rows=26783 width=98)

EXPLAIN
explain select * from documents where iddoc=1;

Index Scan using lotti_pkey on lotti  (cost=0.00..2.26 rows=1 width=98)


Why index is not used for operators > and < 

Alex







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