4. Why can't Qt be installed with SQLite that has load_extension enabled?

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Why can't Qt be installed with SQLite that has load_extension enabled?


  • Several apps that I have that use Qt also use Sqlite. Also, these apps require that Sqlite be able to load extension functions. However, this ability is disabled in the version of Sqlite that is compiled with Qt. So, every time that I want to use a new version of Qt, I have to download the source and recompile QT and the Sqlite plugin. Not only does this take a lot of time, it also eats up huge amounts of disk space. Generally, for my purposes, I have not found it necessary to compile Qt from source for any other reason than to be able to compile the Sqlite plugin.

    A simple solution to this problem could be made by shipping Qt with 2 versions of the Sqlite plugin. One, configured just as at present and the 2nd configured to use a system Sqlite. The user would then be free to use Sqlite of any version configured to his/her needs.

    I am sure that any Sqlite user, including users of Spatialite would appreciate such an enhancement to Qt.

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  • Lifetime Qt Champion

    Hi,

    You don't need to rebuild Qt to rebuild the SQLite plugin. Build the plugin like described here.

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  • @SGaist thanks, I'll try that next time, however it still means that one must download the source package.

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  • I built the plugin with this script:

    CALL "C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat" x64

set QTDIR="C:\Qt5\5.6\Src\"

cd %QTDIR%\qtbase\src\plugins\sqldrivers\sqlite

%QTDIR%\..\msvc2013_64\bin\qmake "INCLUDEPATH+=C:/Progra~1/Sqlite3_3_13/src" "LIBS+=C:/Progra~1/Sqlite3_3_13/SQLITE3.LIB" sqlite.pro

nmake

    This did not work. qmake added the define "ENABLE_LOAD_EXTENSION" but failed to delete "OMIT_LOAD_EXTENSION"

    I solved this problem by manually editing the sqlite.pro file referenced by qmake by adding:

    DEFINES -= SQLITE_OMIT_LOAD_EXTENSION
DEFINES += SQLITE_ENABLE_LOAD_EXTENSION

    This time a sqlite plugin was compiled with the options I wanted but this was not really what I wanted. I wanted to use a system sqlite. So it looks like I must run the config program with the "-system-sqlite" configuration parameter. So it looks like there is no way to do this without running configure.

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  • Lifetime Qt Champion

    Since you are editing sqlite.pro anyway, why not disable the !system-sqlite part and put the include/link path needed for your system sqlite ?

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  • This is what qtbase/src/plugins/sqlite/sqlite.pro looks like after running configure with the -system-sqlite parameter specified.

    TARGET = qsqlite

SOURCES = smain.cpp
OTHER_FILES += sqlite.json
include(../../../sql/drivers/sqlite/qsql_sqlite.pri)

PLUGIN_CLASS_NAME = QSQLiteDriverPlugin
include(../qsqldriverbase.pri)

    Here is the partial output of configure:

    QMAKESPEC...................win32-msvc2013 (commandline)
Architecture................x86_64, features: sse sse2
Host Architecture...........x86_64, features: sse sse2
Maketool....................nmake
Debug build.................yes (combined)
Default build...............debug
Force debug info............no
Force optimized tools.......no
C++ language standard.......auto
Link Time Code Generation...no
Using PCH ..................yes
Accessibility support.......no
RTTI support................yes
SSE support.................SSE2 SSE3 SSSE3 SSE4.1 SSE4.2
AVX support.................AVX AVX2
AVX512 support..............<none>
NEON support................no
OpenGL support..............yes
Large File support..........yes
NIS support.................no
Iconv support...............no
Evdev support...............no
Mtdev support...............no
Inotify support.............no
eventfd(7) support..........no
Glib support................no
CUPS support................no
OpenVG support..............no
SSL support.................no
OpenSSL support.............no
libproxy support............no
Qt D-Bus support............runtime
Qt Widgets module support...yes
Qt GUI module support.......yes
QML debugging...............yes
DirectWrite support.........yes
DirectWrite 2 support.......yes
Use system proxies..........no

QPA Backends:
    GDI.....................yes
    Direct2D................no

Third Party Libraries:
    ZLIB support............qt
    GIF support.............plugin
    JPEG support............plugin
    PNG support.............yes
    DoubleConversion........qt
    FreeType support........yes
    Fontconfig support......no
    HarfBuzz support........qt
    PCRE support............qt
    ICU support.............no
    ANGLE...................yes
    Dynamic OpenGL..........no

Styles:
    Windows.................yes
    Windows XP..............yes
    Windows Vista...........yes
    Fusion..................yes

Sql Drivers:
    ODBC....................no
    MySQL...................no
    OCI.....................no
    PostgreSQL..............no
    TDS.....................no
    DB2.....................no
    SQLite..................plugin (system)
    SQLite2.................no
    InterBase...............no

Sources are in..............C:\Qt5\5.7\Src\qtbase
Build is done in............C:\Qt5\5.7\Src\qtbase
Install prefix..............C:\Qt5\5.7\Src\qtbase
Headers installed to........C:\Qt5\5.7\Src\qtbase\include
Libraries installed to......C:\Qt5\5.7\Src\qtbase\lib
Arch-dep. data to...........C:\Qt5\5.7\Src\qtbase
Plugins installed to........C:\Qt5\5.7\Src\qtbase\plugins
Library execs installed to..C:\Qt5\5.7\Src\qtbase\bin
QML1 imports installed to...C:\Qt5\5.7\Src\qtbase\imports
QML2 imports installed to...C:\Qt5\5.7\Src\qtbase\qml
Binaries installed to.......C:\Qt5\5.7\Src\qtbase\bin
Arch-indep. data to.........C:\Qt5\5.7\Src\qtbase
Docs installed to...........C:\Qt5\5.7\Src\qtbase\doc
Translations installed to...C:\Qt5\5.7\Src\qtbase\translations
Examples installed to.......C:\Qt5\5.7\Src\qtbase\examples
Tests installed to..........C:\Qt5\5.7\Src\qtbase\tests
Include paths...............C:\Progra~1\Sqlite3_3_13\src
Additional libraries........-LC:\Progra~1\Sqlite3_3_13
Using internal configuration.

Info: creating super cache file C:\Qt5\5.7\Src\.qmake.super


Qt is now configured for building. Just run nmake.
To reconfigure, run nmake confclean and configure.

    It does not appear to me that there is any change to the sqlite.pro file that would result in a sqlite plugin configured for system-sqlite.

    I tried using the qmake created by configure but got this result:

    C:\Qt5\5.7\Src\qtbase\src\plugins\sqldrivers\sqlite>%QTDIR%\qtbase\bin\qmake "IN
CLUDEPATH+=C:/Progra~1/Sqlite3_3_13/src" "LIBS+=C:/Progra~1/Sqlite3_3_13/SQLITE3
.LIB" sqlite.pro
Project ERROR: No module claims plugin type 'sqldrivers'

    So how can you create a system sqlite plugin without recompiling QT from source?

    It still seems that if QT were shipped with an alternative sqlite driver that specifies system-sqlite it would make things easier. Alternatively, maybe a run-time parameter to open the plugin could have an extra parameter that specified using the system sqlite instead of the built-in one.

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  • Lifetime Qt Champion

    The .pro file won't be changed.

    The QMAKE_CONFIG will contain system-sqlite which will be used to determine how the plugin will be built.

    Modify the .pro file to remove the check, add the LIBS, INCLUDEPATH and flags you need.

    There's an important difference between the use of the bundled SQLite and a system installed SQLite. The bundled one gets builtin the plugin.

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  • What or where is QMAKE_CONFIG? Remove what check? I'm aware of the difference between the use of the bundled SQLITE and a system installed SQLITE but would like to know how to have QT use a system SQLITE without compiling it from source.

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  • Lifetime Qt Champion

    QMAKE_CONFIG is populated by configure.

    The way it's described in the documentation I linked to. However the name of the lib might be sqlite3 rather that just sqlite

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  • Back up to where I ran configure specifying -system_sqlite. Then I ran qmake on the sqlite.pro file and then nmake, It didn't work; I got an error that I documented there. I believe it requires some other library to be compiled also; maybe qt5sql.dll.

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  • Lifetime Qt Champion

    Which qmake are you using ?

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  • I used the qmake that was created when you run configure.

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  • Lifetime Qt Champion

    Don't, use the qmake from the Qt version you want to build the plugin for.

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  • That doesn't result in a system_sqlite plugin. Why don't you download a fresh copy of QT and you will see what I mean.

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