[GRASS-user] turning sqlite journal off

Nikos Alexandris nik at nikosalexandris.net
Wed May 15 14:53:25 PDT 2019


* Markus Metz <markus.metz.giswork at gmail.com> [2019-05-15 22:55:13 +0200]:

>On Tue, May 14, 2019 at 11:12 AM Panagiotis Mavrogiorgos <pmav99 at gmail.com>
>wrote:
>>
>> Hi Laura,
>>
>> This thread seems to be related:
>http://osgeo-org.1560.x6.nabble.com/SQLITE-db-locking-problem-td5182180.html
>> I also had a somewhat similar problem that was related to the VACUUM
>command issued when closing a GRASS session (new session started before the
>VACUUM of the previous session was finished)
>> If I understand this correctly, you are not supposed to concurrently use
>the same sqlite database.
>
>Yes, this is a limitation of sqlite, and the GRASS-internal sqlite driver
>has been adapted accordingly as much as possible.

Nevertheless, concurrent reading is allowed.  Reading the discussion so
far, one may think that no concurrent use is possible at all.

See also https://sqlite.org/whentouse.html :

  "SQLite supports an unlimited number of simultaneous readers, but it
  will only allow one writer at any instant in time."

And in https://sqlite.org/lockingv3.html see 'SHARED'.
Also, https://stackoverflow.com/a/4060838/1172302.

Nikos


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