Re: [sqlite] index for a group by

2009-10-21 Thread Simon Slavin
On 21 Oct 2009, at 11:34pm, Sylvain Pointeau wrote: > if your "book" contains all lines (a,b,c,t,d)and you create an index > on > (a,b,c,t) I assume you meant to add ',d'in there. > then your index is as fat as your book, isn't it? Yes. And it still isn't as useful for any SELECT that doesn

Re: [sqlite] index for a group by

2009-10-21 Thread Nicolas Williams
On Thu, Oct 22, 2009 at 12:34:26AM +0200, Sylvain Pointeau wrote: > if your "book" contains all lines (a,b,c,t,d)and you create an index on > (a,b,c,t) > > then your index is as fat as your book, isn't it? Depends on the size of d. Also, if you add a constraint declaring t, a, b, and c (you want

Re: [sqlite] index for a group by

2009-10-21 Thread Sylvain Pointeau
if your "book" contains all lines (a,b,c,t,d)and you create an index on (a,b,c,t) then your index is as fat as your book, isn't it? cheers, Sylvain On Wed, Oct 21, 2009 at 11:52 PM, Simon Slavin wrote: > > On 21 Oct 2009, at 9:19pm, Sylvain Pointeau wrote: > > > Thank you for your answers. > >

Re: [sqlite] index for a group by

2009-10-21 Thread Simon Slavin
On 21 Oct 2009, at 9:19pm, Sylvain Pointeau wrote: > Thank you for your answers. > knowing that I have a table T (a,b,c,d,t) > where d is a value > a,b,c some dimensions > and t the time > > where I need to make a subset with a "group by" like > > select a,b,c,sum(d) > from T > where t>x1 and t g

Re: [sqlite] index for a group by

2009-10-21 Thread Sylvain Pointeau
the individual transactions you avoid, which makes a huge > difference. > > John > > -Original Message- > From: sqlite-users-boun...@sqlite.org > [mailto:sqlite-users-boun...@sqlite.org] On Behalf Of Pavel Ivanov > Sent: Tuesday, October 20, 2009 2:47 PM > To: General Discussio

Re: [sqlite] index for a group by

2009-10-20 Thread John Crenshaw
you avoid, which makes a huge difference. John -Original Message- From: sqlite-users-boun...@sqlite.org [mailto:sqlite-users-boun...@sqlite.org] On Behalf Of Pavel Ivanov Sent: Tuesday, October 20, 2009 2:47 PM To: General Discussion of SQLite Database Subject: Re: [sqlite] index for a g

Re: [sqlite] index for a group by

2009-10-20 Thread Pavel Ivanov
e more btree than that, increase the size, or split across > several transactions. > > John > > -Original Message- > From: sqlite-users-boun...@sqlite.org > [mailto:sqlite-users-boun...@sqlite.org] On Behalf Of Pavel Ivanov > Sent: Tuesday, October 20, 2009 7:35 AM &

Re: [sqlite] index for a group by

2009-10-20 Thread John Crenshaw
Sent: Tuesday, October 20, 2009 7:35 AM To: General Discussion of SQLite Database Subject: Re: [sqlite] index for a group by > please could you let me know which index could be better or faster? For this particular query index on (t,a,b,c) or even on (t,a,b,c,d) would be better and cause the q

Re: [sqlite] index for a group by

2009-10-20 Thread Pavel Ivanov
> please could you let me know which index could be better or faster? For this particular query index on (t,a,b,c) or even on (t,a,b,c,d) would be better and cause the query to execute faster (of course if by conditions t>x1 and t also do you know by chance how to speed up the index creation? The

[sqlite] index for a group by

2009-10-19 Thread Sylvain Pointeau
hello, I have a table T (a,b,c,d,t) where c is a value a,b,c some dimensions and t the time I need to make a subset with a "group by" like select a,b,c,sum(d) from T where t>x1 and thttp://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users