On 5/23/2012 1:51 PM, Sander Jansen wrote:
I was always under the impression that prepared statements can only be
used from one thread at a time, so if 2 threads need to perform the
same query independently, you need to have a prepared statement for
each thread. Now I came across the following which seems to contradict
this:
"
http://www.sqlite.org/c3ref/c_config_getmalloc.html#sqliteconfigserialized
There is no contradiction. Basically, there's a mutex associated with a
connection, and sqlite3_step as well as other API functions acquire it
on entry and release it on exit. So, while it is safe to call
sqlite3_step on the same statement from multiple threads, it is rather
pointless, since a) all these calls are going to be serialized on the
mutex so you won't actually get any parallelism out of this, and b) the
statement is traversing the same single resultset, so each thread will
see some random subset of the rows, depending on how their calls happen
to interleave.
--
Igor Tandetnik
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