On 2018-09-16 1:29 AM, John Found wrote:
Is there some relation between the indexes used in the query, the GROUP BY
fields used
and the order of the result rows, when no "ORDER BY" clause is used?
I am asking, because I noticed, that on some queries, when I am using "ORDER
BY" the query
On Sun, 16 Sep 2018 10:59:31 -0400
Richard Hipp wrote:
> On 9/16/18, John Found wrote:
> >
> > Is it means that in every query that uses GROUP BY and ORDER BY
> > simultaneously, one of the operations will always be provided by using
> > temporary b-tree?
> >
>
> no.
>
> CREATE TABLE
I know that the answer is "no", but in the below example, group by clause
is meaningless, because (a,b) is primary key and there is no two rows with equal
(a, b) that to be grouped.
Please, comment my example from the first email in the thread.
Is it possible to make this query to group by and
On 9/16/18, John Found wrote:
>
> Is it means that in every query that uses GROUP BY and ORDER BY
> simultaneously, one of the operations will always be provided by using
> temporary b-tree?
>
no.
CREATE TABLE t1(a,b,c, PRIMARY KEY(a,b)) WITHOUT ROWID;
explain query plan
SELECT a, b, sum(c)
On Sun, 16 Sep 2018 13:30:55 +0100
Simon Slavin wrote:
> On 16 Sep 2018, at 9:29am, John Found wrote:
>
> > Is there some relation between the indexes used in the query, the GROUP BY
> > fields used
> > and the order of the result rows, when no "ORDER BY" clause is used?
>
> When you ask
On 16 Sep 2018, at 9:29am, John Found wrote:
> Is there some relation between the indexes used in the query, the GROUP BY
> fields used
> and the order of the result rows, when no "ORDER BY" clause is used?
When you ask for GROUP BY, SQLite internally does the same sort of thing as it
does
On Sun, 16 Sep 2018 19:27:40 +1000
Barry Smith wrote:
> Without an order by, sqlite can return the rows in any order it pleases.
> Likely whatever consumes the least resources. Although unlikely given your
> indices, it might be possible - for instance if some future
> micro-optimisation
Without an order by, sqlite can return the rows in any order it pleases. Likely
whatever consumes the least resources. Although unlikely given your indices, it
might be possible - for instance if some future micro-optimisation finds that
it's quicker to read the index in reverse, then sqlite
Is there some relation between the indexes used in the query, the GROUP BY
fields used
and the order of the result rows, when no "ORDER BY" clause is used?
I am asking, because I noticed, that on some queries, when I am using "ORDER
BY" the query always
use temporary b-tree for ordering, but
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