为什么 yum 命令不行

[root@localhost ~]# yum -y install gcc

rpmdb: /var/lib/rpm/Packages: file size not a multiple of the pagesize

error: cannot open Packages index using db3 - 无效的参数 (22)

error: cannot open Packages database in /var/lib/rpm

CRITICAL:yum.main:

Error: rpmdb open failed