[sqlite] Contstant WHERE terms still require table scan?

[no...@null.net]

On Fri Jun 12, 2015 at 09:49:29AM +0000, Hick Gunter wrote:
> Seems the correct code is already generated...

Thanks Hick, that shows a bit more detail I didn't think to look for.
It seems that this only works for bind values, as the comparison and goto
statements aren't present when the term is defined at prepare time:

    .width 4 10 4 4 4 10 2 10
    EXPLAIN SELECT
        x.id
    FROM
        x
    WHERE
        1=0
    ;

    addr  opcode      p1    p2    p3    p4          p5  comment   
    ----  ----------  ----  ----  ----  ----------  --  ----------
    0     Init        0     9     0                 00  NULL      
    1     Ne          2     7     1                 51  NULL      
    2     OpenRead    0     2     0     0           00  NULL      
    3     Rewind      0     7     0                 00  NULL      
    4     Rowid       0     3     0                 00  NULL      
    5     ResultRow   3     1     0                 00  NULL      
    6     Next        0     4     0                 01  NULL      
    7     Close       0     0     0                 00  NULL      
    8     Halt        0     0     0                 00  NULL      
    9     Transactio  0     0     1     0           01  NULL      
    10    TableLock   0     2     0     x           00  NULL      
    11    Integer     1     1     0                 00  NULL      
    12    Integer     0     2     0                 00  NULL      
    13    Goto        0     1     0                 00  NULL      

That makes me think that for the 1=0 case the scan occurs anyway?

-- 
Mark Lawrence