sqlite 3.44发布

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才发现，sqlite可以强制用索引

sqlite> CREATE TABLE gravity
   ...> (
(x1...>   domain TEXT NOT NULL,
(x1...>   adlist_id INTEGER NOT NULL REFERENCES adlist (id),
(x1...>   PRIMARY KEY(domain, adlist_id)
(x1...> );
sqlite> explain query plan select count(*) from (select distinct domain from gravity);
QUERY PLAN
|--CO-ROUTINE (subquery-1)
|  `--SCAN gravity USING COVERING INDEX sqlite_autoindex_gravity_1
`--SCAN (subquery-1)
sqlite> explain query plan select count(distinct domain) from gravity;
QUERY PLAN
|--USE TEMP B-TREE FOR count(DISTINCT)
sqlite> explain query plan select count(distinct domain) from gravity INDEXED BY sqlite_autoindex_gravity_1;
QUERY PLAN
`--SCAN gravity USING COVERING INDEX sqlite_autoindex_gravity_1
sqlite> CREATE INDEX idx_gravity_domains_only ON gravity (domain);
sqlite> explain query plan select count(distinct domain) from gravity;
QUERY PLAN
`--SCAN gravity USING COVERING INDEX idx_gravity_domains_only
sqlite>

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3.45.2发布

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3.45.3发布

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3.46.1发布
https://sqlite.org/releaselog/3_46_1.html