Hello.
I have two tables to join. TABLE_A (contains column 'a') and TABLE_BC (contains
columns 'b' and 'c'). There is a condition on TABLE_BC. The two tables are
joined by 'rowid'.
Something like:
SELECT a, b, c FROM main.TABLE_A INNER JOIN main.TABLE_BC WHERE (b > 10.0 AND c
< 10.0) ON main.TABLE_A.rowid = main.TABLE_BC.rowid ORDER BY a;
Alternatively:
SELECT a, b, c FROM main.TABLE_A AS s1 INNER JOIN (SELECT rowid, b, c FROM
main.TABLE_BC WHERE (b > 10.0 AND c < 10.0)) AS s2 ON s1.rowid = s2.rowid ORDER
BY a;
I need to do this a couple of time with different TABLE_A, but TABLE_BC does
not change... I could therefore speed things up by creating a temporary
in-memory database (mem) for the constant part of the query.
CREATE TABLE mem.cache AS SELECT rowid, b, c FROM main.TABLE_BC WHERE (b > 10.0
AND c < 10.0);
followed by (many):
SELECT a, b, c FROM main.TABLE_A INNER JOIN mem.cache ON main.TABLE_A.rowid =
mem.cache.rowid ORDER BY a;
I get the same result set from all the queries above, but the last option is by
far the fastest one.
The problem is that I would like to avoid splitting the query into two parts. I
would expect SQLite to do the same thing for me automatically (at least in the
second scenario), but it does not seem to happen... Why is that?
Thanks.
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