Time issue when selecting several columns about matlab-sqlite3-driver HOT 2 OPEN

@florentmathieu Thanks for reporting this. Probably this is due to the driver API.

There could be several reasons. Perhaps the biggest is time to allocate memory during construction. The current implementation first keeps the copy of the database rows in C++ array then converts all the array items to Matlab objects so that in the first stage the number of items can be calculated.

https://github.com/kyamagu/matlab-sqlite3-driver/blob/master/src/sqlite3mex.cc#L263

The current implementation works but inefficiently consumes memory due to the first conversion. When there are more columns, the converter takes more time to allocate memory. I suspect this is the main reason why retrieving multiple columns gets slow.

Currently there is also the official API by Mathworks. Maybe you can check if alternative implementation solves this issue?

https://www.mathworks.com/help/database/ug/working-with-the-matlab-interface-to-sqlite.html

from matlab-sqlite3-driver.

Hello,
thanks for the quick reply. Indeed it can explain that kind of behavior. I didn't realize there was an official API now, maybe I'll check this one. I'm quite happy with yours already, but I'll see when I find time.

from matlab-sqlite3-driver.