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Overview
Comment:More details in the header comment of pushDownWhereTerms(). No changes to code.
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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
Unified Diff Show Whitespace Changes Patch
Changes to src/select.c.
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** 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 **)




**
**   (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








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3827
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3830
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3837
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** 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.
**           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
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