Hi all,
I create a table with 200 columns, then use sqlite3_prepare() and
sqlite3_step()
to get a record by this: "select * from tbl where ID =.. ". Test in my
embedded system
The total time is about 65ms,it is too long for the performance
requirement, I found
sqlite3_prepare() time is about 50ms. Then test the code with VTune, I
found
lookupName() function in Sqlite take about 50% of the total time,
and sqlite3StrICmp() occupied most execution time (867/922, see the
follow pics ) in lookupName().
The follow is the graph info link grnerate by VTune:
http://img15.tianya.cn/photo/2008/11/18/10872206_2807293.jpg
http://img15.tianya.cn/photo/2008/11/18/10872205_2807293.jpg
If use "select * from tbl where...." ,tbl is a table with 200
columns,
sqlite3StrICmp() will be executed more than 20000 times in
lookupName()，this
is the main bottleneck
in sqlite3_prepare().
I think maybe Sqlite should do a special Optimization for "select
*.......", and there is
no necessary to compare the column names expand by "*" with the table
column names.
Are there some efficient ways to get a whole record with many many
columns ?
Thanks very much!
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