Hwllo,
On 2018-01-05 21:19, x wrote:
Tbl has 2.4 million records and has an INTEGER PRIMARY KEY ID which is NOT NULL.
SELECT ID FROM Tbl where ID = NULL
It has no sense as ``='' returns NULL when one of operands is NULL. NULL
evaluates to FALSE. Above query can be described as SELECT NOTHING.
SELECT ID FROM Tbl WHERE ID IS NULL
takes around 350 milliseconds to run and the explain query plan shows it uses
some covering index.
SQLite is looking for NULL values of ID.
Please, please, do not require to optimize such query due to the fact
that your field does not contain NULLs. :-)
I’m sure I’ve read something before about this but can’t find it in the
documentation?
STH IS STH allows NULLs and returns 1 if both are NULLs, 0 otherwise.
http://sqlite.org/lang_expr.html#isisnot
-- best regards
Cezary H. Noweta
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