当准备“选择”时，SQLite DB（具有WAL）被锁定。 statmement - 为什么？ [英] SQLite DB (with WAL) locked when preparing a "select" statmement - why?
问题描述
我的设置：
p>- SQLite3数据库，journal_mode = WAL，synchronous = NORMAL
- 多个C ++进程使用数据库 - 这些进程中的任何方法都会用
sqlite3_open_v2打开和关闭自己的非共享连接。 - 在
SQLITE_OPEN_READWRITE模式中打开db - 从数据库读取的方法（即仅执行select语句） $ c> SQLITE_OPEN_READONLY 模式
在wAL模式下，我相信应该可以同时有读者，是一个写入。
然而我看到数据库被锁定当我准备一个select语句使用 sqlite3_prepare_v2
我可以做什么错误，导致读者被阻止？我误解了读实际上是什么？
任何提示赞赏，
感谢：）
检查每个sqlite3_step之后是否有sqlite3_reset，因为这是一种导致数据库被锁定的错误。
在使用sqlite3_prepare准备语句并使用sqlite3_step执行之后，您需要总是使用sqlite3_reset重置它。
sqlite3_reset S）接口将准备语句S重置为
程序的开始。
希望这解决了您的问题。 。!!!
I am seeing my reads getting blocked by the writes to the database which is in WAL mode - I'm stumped as to why.
My setup:
- SQLite3 database, journal_mode=WAL, synchronous=NORMAL
- Mulitple C++ processes (3 to be exact) use the database - Any method within these process open and close their own non-shared connection with
sqlite3_open_v2. - Methods that are inserting data open the db in
SQLITE_OPEN_READWRITEmode - Methods that read from the database (i.e. only do select statements) open the db in
SQLITE_OPEN_READONLYmode
In WAL mode I believe it should be possible to have concurrent readers whilst there is a write occuring.
Yet I am seeing "database is locked" when I am preparing a select statement using sqlite3_prepare_v2
What could I be doing wrong which is causing the reader to get blocked? Am I misunderstanding what a "Read" actually is?
Any tips appreciated,
thanks :)
check whether you have sqlite3_reset after every sqlite3_step because this is one case that causes database is locked error. after preparing a statement with sqlite3_prepare and executing it with sqlite3_step,you need to always reset it with sqlite3_reset.
The sqlite3_reset(S) interface resets the prepared statement S back to the beginning of its program.
hope this solves your problem...!!!
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