SQLite 3.25.1 发布，零配置的 SQL 数据库引擎

SQLite Release 3.25.1 发布了，SQLite 是一个开源、跨平台、免费的小型 C 库，实现了一个独立的、可嵌入的、事务性的、无服务器和零配置的 SQL 数据库引擎。更新如下：

1. Add support for window functions
2. Enhancements the ALTER TABLE command:
   1. Add support for renaming columns within a table using ALTER TABLE table RENAME COLUMN oldname TO newname.
   2. Fix table rename feature so that it also updates references to the renamed table in triggers and views.
3. Query optimizer improvements:
   1. Avoid unnecessary loads of columns in an aggregate query that are not within an aggregate function and that are not part of the GROUP BY clause.
   2. The IN-early-out optimization: When doing a look-up on a multi-column index and an IN operator is used on a column other than the left-most column, then if no rows match against the first IN value, check to make sure there exist rows that match the columns to the right before continuing with the next IN value.
   3. Use the transitive property to try to propagate constant values within the WHERE clause. For example, convert “a=99 AND b=a” into “a=99 AND b=99”.
4. Use a separate mutex on every inode in the unix VFS, rather than a single mutex shared among them all, for slightly better concurrency in multi-threaded environments.
5. Enhance the PRAGMA integrity_check command for improved detection of problems on the page freelist.
6. Output infinity as 1e999 in the “.dump” command of the command-line shell.
7. Added the SQLITE_FCNTL_DATA_VERSION file-control.
8. Added the Geopoly module

   Bug fixes:

9. The ORDER BY LIMIT optimization might have caused an infinite loop in the byte code of the prepared statement under very obscure circumstances, due to a confluence of minor defects in the query optimizer. Fix for ticket 9936b2fa443fec03ff25
10. On an UPSERT when the order of constraint checks is rearranged, ensure that the affinity transformations on the inserted content occur before any of the constraint checks. Fix for ticket 79cad5e4b2e219dd197242e9e.
11. Avoid using a prepared statement for “.stats on” command of the CLI after it has been closed by the “.eqp full” logicc. Fix for ticket 7be932dfa60a8a6b3b26bcf76.
12. The LIKE optimization was generating incorrect byte-code and hence getting the wrong answer if the left-hand operand has numeric affinity and the right-hand-side pattern is ‘/%’ or if the pattern begins with the ESCAPE character. Fix for ticket c94369cae9b561b1f996d0054b

详情见发布公告。

转自 https://www.oschina.net/news/100180/sqlite-3-25-1-released