I was thinking more of general (not just LIMIT 1) optimization:
http://en.wikipedia.org/wiki/Partial_sorting
On Sun, Apr 7, 2013 at 6:16 PM, Simon Slavin wrote:
>
> On 7 Apr 2013, at 3:51pm, Stephen Chrzanowski wrote:
>
> > I don't know if it'd be an interesting optimization. Who's to say what
On 7 Apr 2013, at 6:56pm, Richard Hipp wrote:
> It uses a btree as a priority queue. If you have LIMIT N, then it
> initially starts putting results into the btree until the btree contains N
> entries. Then for each additional row, it first adds the value to the
> btree, then removes the large
On Sun, Apr 7, 2013 at 9:08 AM, Baruch Burstein wrote:
> If I issue a select statement with a ORDER BY clause and a LIMIT clause,
> does SQLite do a full sort (assuming no index) and then return the first X
> rows, or just a partial sort to get the first X sorted results?
>
It uses a btree as a p
Stephen Chrzanowski wrote:
> I don't know if it'd be an interesting optimization. Who's to say what the
> order ends up as prior to the sort?
When doing a merge sort, it would actually be possible to abort the very
last merge step when the first LIMIT entries have been merged.
I might be wrong,
On 7 Apr 2013, at 3:51pm, Stephen Chrzanowski wrote:
> I don't know if it'd be an interesting optimization. Who's to say what the
> order ends up as prior to the sort? Take for example if I have a list of
> dollars and cents being returned from a query. I want the 5 top highest
> cost items o
I don't know if it'd be an interesting optimization. Who's to say what the
order ends up as prior to the sort? Take for example if I have a list of
dollars and cents being returned from a query. I want the 5 top highest
cost items out of 6 possibilities, if I keep the top 5 unsorted, item 6
coul
On 7 Apr 2013, at 2:08pm, Baruch Burstein wrote:
> If I issue a select statement with a ORDER BY clause and a LIMIT clause,
> does SQLite do a full sort (assuming no index) and then return the first X
> rows, or just a partial sort to get the first X sorted results?
The ORDER BY clause does not
If I issue a select statement with a ORDER BY clause and a LIMIT clause,
does SQLite do a full sort (assuming no index) and then return the first X
rows, or just a partial sort to get the first X sorted results?
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