Hello!
On Sunday 11 October 2009 00:54:04 Simon Slavin wrote:
> > Using transactions speeds up a long series of SELECTs because it
> > eliminates the need to re-acquire a read-only file-lock for each
> > individual SELECT.
> >
> > Since in-memory databases have no file locks, I'm not sure that is
> > relevant to this specific case.
>
> I wasn't sure about that. It could still be slower
You can check it very easy.
In transactions:
ve...@veter-laptop:/tmp$ ./test.tcl
19968119 microseconds per iteration
25649514 microseconds per iteration
Without transactions:
ve...@veter-laptop:/tmp$ ./test.tcl
35586024 microseconds per iteration
28630785 microseconds per iteration
$ cat ./test.tcl
#!/usr/bin/tclsh8.5
package require sqlite3
sqlite3 db :memory:
set limit 500000
db eval {create table test(id int primary key, value text)}
puts [time {
db transaction {
for {set i 0} {$i<$limit} {incr i} {
set value "value $i"
db eval {insert into test (value) values ($value)}
}
}
}]
puts [time {
db transaction {
for {set i 0} {$i<$limit} {incr i} {
set rowid [expr round(rand()*$limit)]
db onecolumn {select value from test where rowid=$rowid}
}
}
}]
Best regards, Alexey Pechnikov.
http://pechnikov.tel/
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