[sqlite] obtainingthe number of rows returned by a query (with a limit)

On 5 March 2016 at 23:52, Paul Sanderson wrote: > That doesn't work for me: > > I am trying to avoid (select col1, col2, ... colx ) from ... > > and want just a row count which is much less resource intensive. > Have you measured this? I think you might be surprised as sqlite doesn't keep track

[sqlite] obtainingthe number of rows returned by a query (with a limit)

So select count (*) from ... Doesn't require a crystal ball and returns the number of rows but Select count(*) from ... Limit x Dies need one, interesting On Saturday, 5 March 2016, Igor Tandetnik wrote: > On 3/5/2016 12:20 PM, Paul Sanderson wrote: > >> If it computes many things and

[sqlite] obtainingthe number of rows returned by a query (with a limit)

On 3/5/2016 7:15 PM, Paul Sanderson wrote: > So > > select count (*) from ... > > Doesn't require a crystal ball and returns the number of rows It does however fail to satisfy "before I execute it in full" requirement. It essentially does execute the inner query in full, while counting the rows

[sqlite] obtainingthe number of rows returned by a query (with a limit)

Paul Sanderson wrote: > I have users who need to execute queries that generate a large number > of rows, I have other users that create queries that generate a large > number of rows by accident (i.e. cross joins). I have no control over > what they enter but I want to do something to warn them

[sqlite] obtainingthe number of rows returned by a query (with a limit)

> Just allow them to cancel the query; use sqlite3_progress_handler(). I am using a third party data access component so this is out of my control. If it computes many things and doesn't return many rows then I don't really care. I only want to know how many rows a query will return before I

[sqlite] obtainingthe number of rows returned by a query (with a limit)

On 3/5/2016 12:20 PM, Paul Sanderson wrote: > If it computes many things and doesn't return many rows then I don't > really care. I only want to know how many rows a query will return > before I execute it in full. That would require a crystal ball or a time machine. Absent those, it's

[sqlite] obtainingthe number of rows returned by a query (with a limit)

That doesn't work for me: I am trying to avoid (select col1, col2, ... colx ) from ... and want just a row count which is much less resource intensive. I have users who need to execute queries that generate a large number of rows, I have other users that create queries that generate a large

[sqlite] obtainingthe number of rows returned by a query (with a limit)

Paul Sanderson wrote: > I am trying to determine before a query is executed how many rows will > be returned. the following query works as expected > > select count(*) from table > > but > > select count(*) from table limit 100 > > still returns the number of rows in the table not the number of

[sqlite] obtainingthe number of rows returned by a query (with a limit)

I am trying to determine before a query is executed how many rows will be returned. the following query works as expected select count(*) from table but select count(*) from table limit 100 still returns the number of rows in the table not the number of rows that would be returned by the