On 27.01.2012 15:54, David A Knight wrote:
I have been looking at changing an iOS app over to using Monotouch
and run into an issue with Sqlite performance. Writing some test
code (not running on a device) that just opens a database and does a
number of inserts (in a transaction) the performance difference
between C (using Core Foundation for unicode strings) and C# is
massive. ~37k compared to ~14k inserts per second under MacOSX
(including the iOS simulator) / Linux.
Looking at Mono.Data.Sqlite I can't see any code that would cause
this and so have come to the conclusion (wrongly or rightly) that the
difference in performance is down to Sqlite functions being called
via P/Invoke and the overhead it causes. Is there anything that can
be done to reduce this overhead that isn't already in place? Am I
wrong that the difference is caused by the P/Invoke?
It's hard to say w/out a test case.
If you did not specify SqliteConnection's "UseUTF16Encoding=true"
option, the p/invoke layer would have to marshal strings back and
forth between UTF-8 and UTF-16. This might add substantial overhead
to apps that need 37k transactions per second.
Robert
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