Thanks Igor,your examples really helped me!
--- Igor Tandetnik <[EMAIL PROTECTED]> wrote:
> "L B" <[EMAIL PROTECTED]> wrote in
> message
> news:[EMAIL PROTECTED]
> > Just to better understand, the index on (x,y,z),
> would
> > it be useful for querie
Just to better understand, the index on (x,y,z), would
it be useful for queries like
select * from table1 inner join table2
on table1.x=table2.x and table1.y = table2.y and
table1.z=table2.z
or
"table1.y = table2.y and table1.z=table2.z" would not
benefit the index (so it would be better 3 dif
Thank you very much for your reply, Igor.
The explanation you made is only valid for sqlite or
for SQL in general?
Moreover, the query:
select * from mytable where X=?;
would still benefit the index on (X, Y, Z)?
--- Igor Tandetnik <[EMAIL PROTECTED]> wrote:
> "L B" <[E
Hi all,
I would like to know if there is any difference
between using 3 indexes on three different fields or
just an index which groups them, in terms of physical
size and performance.
I have seen that sqlite cannot use more than one index
at a time, so I was wondering if the second option is
alwa
May be:
select B.* from B left join A on a.id = b.id
where A.id is null
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I have obtained a great performance improvement now
just adding an index in the 2 columns
dtfrom and idcatalogue,
removing the 2 single indexes on the column dtfrom and
idcatalogue.
I could not believe, now the query
SELECT MAX(DTFROM) AS MAXDT, IDCATALOGUE FROM
CRONOCATALOGUES GROUP BY IDCAT
I have investigated more.
It seems that the performance problem is simply
related to the query:
SELECT MAX(DTFROM) AS MAXDT, IDCATALOGUE FROM
CRONOCATALOGUES GROUP BY IDCATALOGUE
which takes at first execution 9 seconds in access and
30 seconds in sqlite, and it takes, after first
execution (OS c
Hi all,
I have a 500mb database in access, migrated to sqlite.
The structure is:
--this table has 100 records
CREATE TABLE CATALOGUES
(
IDCATALOGUE INTEGER PRIMARY KEY AUTOINCREMENT,
CATALOGUENAME TEXT,
IDPERSONALDATA INTEGER,
TYPE INTEGER,
ACTIVE INTEGER
);
C
Thanks Doug.
Is there any suggestion or rules about parameters to use (cache_size,
default_cache_size...) in relation to database size and number of records in a
table?
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Thanks for your reply.
So, as I understand, this performance improvement is due to the operating
system, not to sqlite itself.
Could this improvement be different changing operating system?
When Is it convenient to use SQLite page-cache for large database (example 4
gb) and in which terms?
Hi all,
I have a query that, first time is executed, takes 40 seconds to give results.
After the first execution, it takes about 15 seconds.
My question is: Is the db loaded into memory? I thought db is read from hard
disk every time, isn't it?
Why this difference in performance?
Tha
Hi Dennis, may be I understand now.
I have enabled mail delivery in my sqlite users account options (which was
not enabled before), now I should receive all messages so that I can reply to
one of them.
May be it was my problem, because I have never received any message from
sqlite user m
Sorry for this post, but I can't find a way to reply to a post. It seems that I
can only reply via email to the person who answered me.
How to reply and see my answer on this site?
thanks
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Hi all,
I have this query:
select CATALOGUES.idcatalogue, CATALOGUES.type, PERSONS.surname,
max(HISTORY.startingfrom) as maxdate
FROM PERSONS
INNER JOIN CATALOGUES
ON CATALOGUES.idperson = PERSONS.idperson
INNER JOIN HISTORY
ON HISTORY.idcatal
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