database disk image is malformed

在执行yum更新，即运行 yum update 命令时，提示以下错误：

File "/usr/bin/yum", line 29, in ?
yummain.main(sys.argv[1:])
File "/usr/share/yum-cli/yummain.py", line 97, in main
result, resultmsgs = do()
File "/usr/share/yum-cli/cli.py", line 481, in doCommands
return self.updatePkgs()
File "/usr/share/yum-cli/cli.py", line 957, in updatePkgs
self.doRepoSetup()
File "/usr/share/yum-cli/cli.py", line 82, in doRepoSetup
self.doSackSetup(thisrepo=thisrepo)
File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 291, in
doSackSetup
self.repos.populateSack(which=repos)
File "/usr/lib/python2.4/site-packages/yum/repos.py", line 289, in
populateSack
dobj = repo.cacheHandler.getPrimary(xml, csum)
File "/usr/lib/python2.4/site-packages/yum/sqlitecache.py", line 96, in
getPrimary
return self._getbase(location, checksum, 'primary')
File "/usr/lib/python2.4/site-packages/yum/sqlitecache.py", line 89, in
_getbase
self.updateSqliteCache(db, parser, checksum, metadatatype)
File "/usr/lib/python2.4/site-packages/yum/sqlitecache.py", line 373, in
updateSqliteCache
cur.execute("DELETE FROM "+table+ " where pkgKey in %s" % delpkgs)
File "/usr/lib/python2.4/site-packages/sqlite/main.py", line 244, in
execute
self.rs = self.con.db.execute(SQL)
_sqlite.DatabaseError: database disk image is malformed

估计是由于yum的原数据损坏导致的，与rpm的数据库损坏类似，前者会导致更新不能正常执行，后者会导致安装失败并出现乱码，前者的解决参见yum更新和rpm安装包问题(rpmdb: PANIC: Invalid argument)，后者的错误可以通过一下方法解决：
终端，依次输入：
1.) yum clean metadata
2.) yum clean dbcache
3.) yum makecache
即先删除原数据和数据库缓存，然后重建之，问题即可解决