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When the estimated cost to do a sort overwhelms the estimated cost to do

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individual table lookups, make sure that the table lookup costs are still
taken into consideration when selecting the lookup algorithm.

FossilOrigin-Name: ec5d84ba69c100d9565425ed74040a49e410ea03
This commit is contained in:
drh
2014-08-07 16:50:00 +00:00
parent 858b638d1f
commit ddef5dc044
4 changed files with 83 additions and 16 deletions
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46
test/whereJ.test
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@ -9,7 +9,7 @@
#
#***********************************************************************
#
# This file implements a single regression test for a complex
# This file implements regression tests for a complex
# query planning case.
#
@ -328,4 +328,48 @@ do_execsql_test whereJ-1.4 {
GROUP BY aid;
} {/B-TREE/}
############################################################################
# Ensure that the sorting cost does not swamp the loop costs and cause
# distinctions between individual loop costs to get lost, and hence for
# sub-optimal loops to be chosen.
#
do_execsql_test whereJ-2.1 {
CREATE TABLE tab(
id INTEGER PRIMARY KEY,
minChild INTEGER REFERENCES t1,
maxChild INTEGER REFERENCES t1,
x INTEGER
);
EXPLAIN QUERY PLAN
SELECT t4.x
FROM tab AS t0, tab AS t1, tab AS t2, tab AS t3, tab AS t4
WHERE t0.id=0
AND t1.id BETWEEN t0.minChild AND t0.maxChild
AND t2.id BETWEEN t1.minChild AND t1.maxChild
AND t3.id BETWEEN t2.minChild AND t2.maxChild
AND t4.id BETWEEN t3.minChild AND t3.maxChild
ORDER BY t4.x;
} {~/SCAN/}
do_execsql_test whereJ-2.2 {
EXPLAIN QUERY PLAN
SELECT t4.x
FROM tab AS t0a, tab AS t0b,
tab AS t1a, tab AS t1b,
tab AS t2a, tab AS t2b,
tab AS t3a, tab AS t3b,
tab AS t4
WHERE 1
AND t0a.id=1
AND t1a.id BETWEEN t0a.minChild AND t0a.maxChild
AND t2a.id BETWEEN t1a.minChild AND t1a.maxChild
AND t3a.id BETWEEN t2a.minChild AND t2a.maxChild
AND t0b.id=2
AND t1b.id BETWEEN t0b.minChild AND t0b.maxChild
AND t2b.id BETWEEN t1b.minChild AND t1b.maxChild
AND t3b.id BETWEEN t2b.minChild AND t2b.maxChild
AND t4.id BETWEEN t3a.minChild AND t3b.maxChild
ORDER BY t4.x;
} {~/SCAN/}
finish_test