Hello,
I'm seeing strange input given into xBestIndex method of my virtual table.
I'm maintaining sqlite4java wrapper and I'm trying to upgrade it from SQLite
3.7.4 to 3.7.7.1. A couple of failed tests uncovered that there's a problem
when searching a simple virtual table with constraints that contain NULL.
More specifically, the virtual table is declared as follows in xCreate
method:
CREATE TABLE x(value INTEGER)
When the following SQL is executed:
SELECT value FROM table WHERE value IS NOT NULL
, xBestIndex receives the following parameters:
pIdxInfo->nConstraint == 1
pIdxInfo->aConstraint[0].usable == 1
pIdxInfo->aConstraint[0].iColumn == 0
pIdxInfo->aConstraint[0].op == 4 (GT)
So basically the search is going to be for condition "value > ?".
When xFilter is called, the value passed is NULL. So instead of searching
for "value IS NOT NULL" the module is instructed to search for "value >
NULL" - which gives the opposite result. And when SQL executed is "SELECT
value FROM table WHERE value > NULL", all the parameters are identical.
This problem did not exist in SQLite 3.7.4.
Do I miss something or is this a bug?
Thanks for your help,
Igor
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