SQLite

Check-in [928486231f]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:More details in the header comment of pushDownWhereTerms(). No changes to code.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | prefer-coroutine-sort-subquery
Files: files | file ages | folders
SHA3-256: 928486231ff7cc0df17a5aa23a080a1b8720e168db5227a7dbd34861283ba689
User & Date: drh 2017-09-30 11:47:06.786
Context
2017-10-02
02:52
The query planner now always prefers to implement a FROM-clause subquery using a co-routine rather than flattening the subquery into the outer query. (check-in: c9104b59c7 user: drh tags: trunk)
2017-09-30
11:47
More details in the header comment of pushDownWhereTerms(). No changes to code. (Closed-Leaf check-in: 928486231f user: drh tags: prefer-coroutine-sort-subquery)
10:50
Make sure the SQLITE_Stat34 optimization switch is always 0x800, a value which is hard-coded in the TH3 test suite. (check-in: 6aed4ea34c user: drh tags: prefer-coroutine-sort-subquery)
Changes
Side-by-Side Diff Ignore Whitespace Patch
Changes to src/select.c.
︙
3827
3828
3829
3830
3831
3832
3833
3834





3835
3836
3837
3838
3839
3840
3841

3827
3828
3829
3830
3831
3832
3833

3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845








-
+
+
+
+
+








** The hope is that the terms added to the inner query will make it more
** efficient.
**
** Do not attempt this optimization if:
**
**   (1) (** This restriction was removed on 2017-09-29.  We used to
**           disallow this optimization for aggregate subqueries, but now
**           it is allowed by putting the extra terms on the HAVING clause **)
**           it is allowed by putting the extra terms on the HAVING clause.
**           The added HAVING clause is pointless if the subquery lacks
**           a GROUP BY clause.  But such a HAVING clause is also harmless
**           so there does not appear to be any reason to add extra logic
**           to suppress it. **)
**
**   (2) The inner query is the recursive part of a common table expression.
**
**   (3) The inner query has a LIMIT clause (since the changes to the WHERE
**       close would change the meaning of the LIMIT).
**
**   (4) The inner query is the right operand of a LEFT JOIN.  (The caller
︙