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Adding the "noskipscan" token to an sqlite_stat1.stat field prevents an

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index for being used with the skip-scan algorithm.

FossilOrigin-Name: 00fe09505792cd0d104b2da9d040f023e30fa871
This commit is contained in:
drh
2014-11-15 19:08:13 +00:00
parent dd715f7c57
commit f9df2fbdcd
6 changed files with 37 additions and 11 deletions
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19
test/skipscan1.test
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@ -273,4 +273,23 @@ do_execsql_test skipscan1-6.3 {
EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE b=1;
} {~/ANY/}
# If the sqlite_stat1 entry includes the "noskipscan" token, then never use
# skipscan with that index.
#
do_execsql_test skipscan1-7.1 {
UPDATE sqlite_stat1 SET stat='500000 125000 1 sz=100';
ANALYZE sqlite_master;
EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE b=1;
} {/ANY/}
do_execsql_test skipscan1-7.2 {
UPDATE sqlite_stat1 SET stat='500000 125000 1 noskipscan sz=100';
ANALYZE sqlite_master;
EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE b=1;
} {~/ANY/}
do_execsql_test skipscan1-7.3 {
UPDATE sqlite_stat1 SET stat='500000 125000 1 sz=100 noskipscan';
ANALYZE sqlite_master;
EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE b=1;
} {~/ANY/}
finish_test