[sqlite] Why SQLITE_BUSY?

2015-12-14 Thread sanhua.zh
I queue all my db operation into one thread with single sqlite conn. neither 
multi-thread nor multi-process operation happened.But some SQLITE_BUSY error 
code still be catched.
I can not re-produce this error code indeveloping environment,because it happen 
in alow probability. I only catch this error report online.


So how did it happen?
I guess that, when WAL reach the checkpoint, sqlite will write the data back to 
original db file in background thread. So writing will be busy at this time. 
But I?m not sure.
I hope that you will not stint your criticism


Re: [sqlite] why SQLITE_BUSY when read the database

2010-03-10 Thread a1rex
>Do The words mean that while one process is writing the database other

>processes could not read the database at the same time?

The reader fails since it cannot obtain SHARED lock required for 
reading.
It cannot obtain that lock since the writer already 
managed to obtain PENDING or EXCLUSIVE lock.



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Re: [sqlite] why SQLITE_BUSY when read the database

2010-03-10 Thread a1rex


>Do The words mean that while one process is writing the database other
>processes could not read the database at the same time?

In short:: YES


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[sqlite] why SQLITE_BUSY when read the database

2010-03-10 Thread liubin liu

why SQLITE_BUSY when read the database

My application suffered a problem that sqlite3_step(*) of SELECT returns
SQLITE_BUSY.

I know "Multiple processes can be doing a SELECT at the same time. But only
one process can be making changes to the database at any moment in time,
however." from the sqlite3's faq in the link
http://www.sqlite.org/faq.html#q5;.

Do The words mean that while one process is writing the database other
processes could not read the database at the same time?
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