Re: [sqlite] how is "pragma threads = 4" working

On Fri, 16 Sep 2016 07:29:28 -0400 Richard Hipp wrote: > The algorithm used for "ORDER BY ... LIMIT N" uses much less memory > than a full-up "ORDER BY" because is only keeps track of the top N > entries seen so far, discarding the rest. But it also only uses a > single thread.

Re: [sqlite] how is "pragma threads = 4" working

On 08/15/2016 12:02 AM, Венцислав Русев wrote: My computer has 4 cores. I have compile sqlite like this "gcc -DSQLITE_MAX_WORKER_THREADS=4 -DSQLITE_DEFAULT_WORKER_THREADS=4 shell.c sqlite3.c -lpthread -ldl -o sqlite3". I made some tests and found that "pragma threads = 4" doesn't decrease

Re: [sqlite] how is "pragma threads = 4" working

that is a single sql statement though ; it doesn't spread itself amongst threads, the compile option says 'limits number of threads' so if you had an application (not sqlite shell) that had threads it could have a limit? On Fri, Sep 16, 2016 at 5:13 AM, Adam Devita wrote:

Re: [sqlite] how is "pragma threads = 4" working

Have you proven that the cpu is the bottleneck? Sorting a million rows seems like a lot, but even older single core cpus may be capable of 2 billion ops per second. [I apologize if this has been sorted out already I've got about 2 days of history on the thread] regards, Adam DeVita On Fri,

Re: [sqlite] how is "pragma threads = 4" working

Although programmatically easily done, from the SQLite point of view, what if that query, sans LIMIT, were a subquery, and the limit was put out on the outside? Would the inner query execute, use all the threads, then return just one row on the outer? On Fri, Sep 16, 2016 at 7:29 AM, Richard

Re: [sqlite] how is "pragma threads = 4" working

On 8/14/16, Венцислав Русев wrote: > My computer has 4 cores. I have compile sqlite like this "gcc > -DSQLITE_MAX_WORKER_THREADS=4 -DSQLITE_DEFAULT_WORKER_THREADS=4 shell.c > sqlite3.c -lpthread -ldl -o sqlite3". I made some tests and found that > "pragma threads = 4"

Re: [sqlite] how is "pragma threads = 4" working

On 15 Aug 2016, at 1:02am, Венцислав Русев wrote: > sqlite doesn't use these "auxiliary threads" that sqlite docs talks about and > the runtime of that query is the same with or without "pragma threads = 4". I cannot solve your problem, but this information may help the