Sqlite and performances in LiveCode
jrosat at mac.com
Wed Mar 7 15:08:09 EST 2012
Thank you Pete for that clarification.
Le 7 mars 2012 à 17:37, Pete a écrit :
> I emailed sqlitemanager support re the manage/sql tab performance
> difference. Mystery solved by the reply:
> "In the Manage panel when you see SELECT * FROM table the real query
> executed is SELECT rowid FROM table and then a SELECT * FROM table WHERE
> rowid=N is execute for each visible row of the listbox. In the SQL panel
> query executed is just what you type"
> On Mar 6, 2012 5:47 PM, "Pete" <pete at mollysrevenge.com> wrote:
>> I just noticed that the same vendor that makes SQLiteManager also makes an
>> SQLite server package (cubeSQL) that does implement MVCC. But you're
>> right, it's definitely not there in standard SQLite. An SQLite server
>> sounds interesting though.
>> On Tue, Mar 6, 2012 at 11:35 AM, Bernard Devlin <bdrunrev at gmail.com>wrote:
>>> I notice from things discussed on the Valentina list that they
>>> recommend using API methods rather than SQL calls, because the former
>>> will be faster due to less overhead. So these different ways of
>>> interacting with a sqlite database might well represent an application
>>> using the sqlite API.
>>> Although when I use the Valentina VStudio SQL interface I will still
>>> see results being returned in 25 ms, compared to 500 ms going through
>>> sql yoga > revdb > v4rev sql > valentina. This is doing a "select *"
>>> from a table with 22k rows (10mb in size). That's not to say that I'm
>>> outraged at 500ms. There are other steps one can take to make an
>>> interface responsive at these timescales.
>>> The Valentina guys are pretty used to comparing Livecode with the
>>> other platforms for which they provide Valentina. On 19/12/2010
>>> Ruslan had this to say about Livecode:
>>> "REALbasic - as I remember -- was very fast, near to C code...so it
>>> gives e.g. 5% overhead to pure C engine... Revolution and Director
>>> give me x4-x10 overhead I think....Revolution because all params are
>>> packed to strings ... Director because quite complex SDK similar to MS
>>> COM ..." This conclusion by Ruslan appears to be only in the
>>> discussion of calling the Valentina API, therefore one would expect
>>> that adding other layers (sql, revdb, etc.) one would see other layers
>>> adding their own torpor to the action.
>>> Does using explict transation control make any difference with sqlite?
>>> It shouldn't matter in a case where the data is only being read. I
>>> know on MVCC databases this is still a factor if one has a cursor
>>> containing the read data, as such data might still be altered from the
>>> cursor and the currency control of the MVCC requires a handle on such
>>> data to be able to maintain consistency. I can't see that it would
>>> apply to sqlite, and this site confirms that sqlite does not implement
>>> MVCC: http://www.sqliteconcepts.org/SI_index.html
>>> On Tue, Mar 6, 2012 at 5:15 PM, Pete <pete at mollysrevenge.com> wrote:
>>>> I got the same results on the movies database and even more pronounced
>>>> differences on a table in one of my own databases with ~48k records in
>>>> SQL tab 0.519secs, Manage tab 0.045 secs, more than a 10-fold
>>>> Just a straight SELECT * in each case.
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