sqlite - SQLite：编辑字段，全文更新？

Question

在 SQLite 3 中

如果我更新具有全文索引的字段，全文索引会更新，还是需要手动更新？

Answer 1

例如，这取决于。如果您使用“外部内容 FTS4 表”，它不会自动更新。

来自http://www.sqlite.org/fts3.html#section_6_2_2

CREATE TABLE t2(id INTEGER PRIMARY KEY, a, b, c, d);
CREATE VIRTUAL TABLE t3 USING fts4(content="t2", b, c);

INSERT INTO t2 VALUES(2, 'a b', 'c d', 'e f');
INSERT INTO t2 VALUES(3, 'g h', 'i j', 'k l');
INSERT INTO t3(docid, b, c) SELECT id, b, c FROM t2;
-- The following query returns a single row with two columns containing
-- the text values "i j" and "k l".
--
-- The query uses the full-text index to discover that the MATCH 
-- term matches the row with docid=3. It then retrieves the values
-- of columns b and c from the row with rowid=3 in the content table
-- to return.
--
SELECT * FROM t3 WHERE t3 MATCH 'k';

-- Following the UPDATE, the query still returns a single row, this
-- time containing the text values "xxx" and "yyy". This is because the
-- full-text index still indicates that the row with docid=3 matches
-- the FTS4 query 'k', even though the documents stored in the content
-- table have been modified.
--
UPDATE t2 SET b = 'xxx', c = 'yyy' WHERE rowid = 3;
SELECT * FROM t3 WHERE t3 MATCH 'k';

但也可以通过触发器解决。

一些用户可能希望使用数据库触发器来保持全文索引相对于存储在内容表中的文档集保持最新，而不是单独写入全文索引和内容表。例如，使用前面示例中的表：