SQLite open shared

[mk-soft]

How to open SQLite Database as shared

[infratec]

In general: bad idea.
It is not build for multi user usage.
There is no record locking and so on.

But there are attempts to do it.

http://purebasic.fr/english/viewtopic.php?f=14&t=43203

http://www.purebasic.fr/english/viewtop ... 14&t=63738

Bernd

[mk-soft]

I mean this
https://www.sqlite.org/lockingv3.html#shared_lock

I think Purebasic open database as unlocked

[mrjiles]

I am looking into this at the moment as well.

This article states the SQLite can be used for multiple concurrent read connections, but only a single write connection. https://www.sqlite.org/whentouse.html. From using PB, it appears the database is locked, even when only reading from the database.

mk-soft, are you planning on accessing the database via network share?

[infratec]

Hi,

maybe this helps:

Code: Select all

UseSQLiteDatabase()

DB = OpenDatabase(#PB_Any, ":memory:", "", "")
If DB
  
  If DatabaseUpdate(DB, "PRAGMA query_only=true") = 0
    Debug DatabaseError()
  EndIf
  
  If DatabaseUpdate(DB, "CREATE TABLE test (text VARCHAR(255))") = 0
    Debug DatabaseError()
  EndIf
  
  If DatabaseUpdate(DB, "PRAGMA query_only=false") = 0
    Debug DatabaseError()
  EndIf
  
  If DatabaseUpdate(DB, "CREATE TABLE test (text VARCHAR(255))") = 0
    Debug DatabaseError()
  Else
    Debug "Created"
  EndIf
  
  CloseDatabase(DB)
EndIf

See here:
https://www.sqlite.org/pragma.html

Bernd

[infratec]

Maybe you have to set the PRAGMA locking_mode to NORMAL.
Maybe it is set to EXCLUSIVE by PB.

Bernd

[mrjiles]

What about Write-Ahead Logging https://www.sqlite.org/wal.html?

Code: Select all

If DatabaseUpdate(DB, "PRAGMA journal_mode=WAL") = 0
    Debug DatabaseError()
  EndIf

This appears to be working as intended, but I haven't tested it yet. Would this create the desired result of concurrent access?

[mk-soft]

I think it´s a question to Fred.
Needed an optional parameter for open database as shared.

[infratec]

Hi,

I think you are wrong.
This SHARED is only handled internal of SQLite.
Read 5.0 Writing to a database file on the link you provided above.

I think it has nothing todo with how you open the database file.

Bernd

[siesit]

I will test later
thankee