How to fix "DB error: database disk image is malformed"

[matlabbe]

If you try to use a database and you get this error:

[FATAL] (2022-11-08 20:16:15.028) DBDriverSqlite3.cpp:521::executeNoResultQuery() Condition (rc == SQLITE_OK) not met! 
[DB error: database disk image is malformed, the query is PRAGMA cache_size = 10000;]
terminate called after throwing an instance of 'UException'
  what():  [FATAL] (2022-11-08 20:16:15.028) DBDriverSqlite3.cpp:521::executeNoResultQuery() Condition (rc == SQLITE_OK) not met! 
[DB error: database disk image is malformed, the query is PRAGMA cache_size = 10000;]
Aborted (core dumped)

it means for some reason the database file got corrupted (e.g. the robot lost power while creating the map). To recover, as explained in this post, create fix_db.sh with this code:

#!/bin/bash

cat <( sqlite3 "$1" .dump | grep "^ROLLBACK" -v ) <( echo "COMMIT;" ) | sqlite3 "fix_$1"

Usage:

chmod +x fix_db.sh
./fix_db.sh rtabmap.db

The file fix_rtabmap.db is created and you would be able to open it again in rtabmap-dabatabaseViewer. However, if the file has been corrupted during mapping, it is likely that the visual dictionary hasn't been saved correctly. To recover the database, do:

rtabmap-recovery fix_rtabmap.db

The database fix_rtabmap.db should be now correctly recovered and safe to use.