Javier,
we don't explicitly write temporary files, but sqlite3 can decide to do
so (typically for a "heavy" request like listing all CRS with an order
clause in it). https://sqlite.org/c3ref/temp_directory.html mentions
"SQLite performs a search for an appropriate temporary file
directory.". Not very helpful. Source code at
https://github.com/sqlite/sqlite/blob/da67225f04ad0470b54433fee31baf266e6630ef/src/os_unix.c#L6262
shows it tries in that order (for Unix systems): SQLITE_TMPDIR env var,
TMPDIR env var, /var/tmp, /usr/tmp, /tmp and "."
For the embed proj.db, we have
https://github.com/OSGeo/PROJ/blob/master/src/memvfs.c#L300 , which
basically redirects to the above logic
Even
Le 24/02/2026 à 16:34, Javier Jimenez Shaw via PROJ a écrit :
Hi
We are having problems with sqlite3 and disk while running on iOS. It
happens only from time to time. Restarting the application is usually
enough.
The first case returns an sqlite3 error 13: "database or disk is full"
https://sqlite.org/rescode.html#full
This is the message (trimmed)
Fatal Exception:osgeo::proj::io::FactoryException
SQLite error [ code = 13, msg = database or disk is full ] on SELECT * FROM
(SELECT
c.auth_name, c.code,c.name <http://c.name>, c.type, c.deprecated, a.west_lon,
a.south_lat, a.east_lon,
a.north_lat, a.description, NULL,cb.name <http://cb.name> FROM geodetic_crs c
LEFT JOIN usage u ON
u.object_table_name = 'geodetic_crs'...
And this is the stack trace
8 libc++abi.dylib 0x11bdcstd::__terminate(void (*)()) + 16
9 libc++abi.dylib 0x15314 __cxa_get_exception_ptr + 86
10 libc++abi.dylib 0x152bc
__cxxabiv1::failed_throw(__cxxabiv1::__cxa_exception*) + 90
11 proj
0x168434osgeo::proj::io::SQLiteHandle::run(sqlite3_stmt*,std::__1::basic_string<char,std::__1::char_traits<char>,std::__1::allocator<char>>
const&,std::__1::list<osgeo::proj::io::SQLValues,std::__1::allocator<osgeo::proj::io::SQLValues>>
const&, bool) + 1468
12 proj
0x16a6e8osgeo::proj::io::DatabaseContext::Private::run(std::__1::basic_string<char,std::__1::char_traits<char>,std::__1::allocator<char>>
const&,std::__1::list<osgeo::proj::io::SQLValues,std::__1::allocator<osgeo::proj::io::SQLValues>>
const&, bool) + 1220
13 proj 0x1ad76cosgeo::proj::io::AuthorityFactory::getCRSInfoList() const + 2332
...
There is another similar (but different) issue with error 10: "disk
I/O error" https://sqlite.org/rescode.html#ioerr
Fatal Exception:osgeo::proj::io::FactoryException
SQLite error [ code = 10, msg = disk I/O error ] on SELECT name FROM
"geodetic_datum" WHERE auth_name = ? AND code = ?
Stack trace
9 libc++abi.dylib 0x11b80 std::terminate() + 108
10 proj 0x8270 __clang_call_terminate + 14
11 proj 0xad1e8
osgeo::proj::common::IdentifiedObject::_isEquivalentTo(osgeo::proj::common::IdentifiedObject
const*, osgeo::proj::util::IComparable::Criterion,
std::__1::shared_ptr<osgeo::proj::io::DatabaseContext> const&) const +
234 12 proj 0xe82f4
osgeo::proj::datum::Datum::_isEquivalentTo(osgeo::proj::util::IComparable
const*, osgeo::proj::util::IComparable::Criterion,
std::__1::shared_ptr<osgeo::proj::io::DatabaseContext> const&) const +
100 13 proj 0xed7ac
osgeo::proj::datum::GeodeticReferenceFrame::isEquivalentToNoExactTypeCheck(osgeo::proj::util::IComparable
const*, osgeo::proj::util::IComparable::Criterion,
std::__1::shared_ptr<osgeo::proj::io::DatabaseContext> const&) const +
96 14 proj 0xc0774
osgeo::proj::crs::SingleCRS::baseIsEquivalentTo(osgeo::proj::util::IComparable
const*, osgeo::proj::util::IComparable::Criterion,
std::__1::shared_ptr<osgeo::proj::io::DatabaseContext> const&) const +
456 15 proj 0xc8eb0
osgeo::proj::crs::GeographicCRS::_isEquivalentTo(osgeo::proj::util::IComparable
const*, osgeo::proj::util::IComparable::Criterion,
std::__1::shared_ptr<osgeo::proj::io::DatabaseContext> const&) const +
172 16 proj 0xc627c
osgeo::proj::crs::GeodeticCRS::identify(std::__1::shared_ptr<osgeo::proj::io::AuthorityFactory>
const&) const + 724 17 proj 0xd072c
osgeo::proj::crs::ProjectedCRS::identify(std::__1::shared_ptr<osgeo::proj::io::AuthorityFactory>
const&) const + 1184 18 proj 0xd4028
osgeo::proj::crs::ProjectedCRS::_identify(std::__1::shared_ptr<osgeo::proj::io::AuthorityFactory>
const&) const + 44 ...
Are we writing anything to disk at runtime related to sqlite3? Even a
temporary file? Where?
If yes, would this problem be fixed if we embed proj.db in the
library? Currently we are using it as an external file.
My only guess would be that sqlite3 is creating a temporary file in a
folder with very little space (like /tmp), because the phone should
have a lot of free space for normal storage.
Thank you
Javier.
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