问题描述：

postgresql镜像站在ubuntu 18.04下无法使用，apt update的时候报错:

Get:4 https://repo.huaweicloud.com/postgresql/repos/apt bionic-pgdg InRelease [104 kB]                                                        
Get:5 https://repo.huaweicloud.com/postgresql/repos/apt bionic-pgdg/main i386 Packages [230 kB]         
Err:5 https://repo.huaweicloud.com/postgresql/repos/apt bionic-pgdg/main i386 Packages
  File has unexpected size (231546 != 230074). Mirror sync in progress? [IP: 218.1.70.85 443]
  Hashes of expected file:
   - Filesize:230074 [weak]
   - SHA256:16fffd7bd37fed9efc68f8a087142f42f47afa3596041f72cd08f2e9aa5c03c8
   - SHA1:1271f269071261a2e0cd132df5396c45b223eab6 [weak]
   - MD5Sum:2963a72fec35e1e75d25d2b4918596dd [weak]
  Release file created at: Tue, 02 Feb 2021 17:08:28 +0000
Get:6 https://repo.huaweicloud.com/postgresql/repos/apt bionic-pgdg/main amd64 Packages [231 kB]
Err:6 https://repo.huaweicloud.com/postgresql/repos/apt bionic-pgdg/main amd64 Packages

Fetched 104 kB in 1s (134 kB/s)            
Reading package lists... Done
E: Failed to fetch https://repo.huaweicloud.com/postgresql/repos/apt/dists/bionic-pgdg/main/binary-i386/Packages.bz2  File has unexpected size (231546 != 230074). Mirror sync in progress? [IP: 218.1.70.85 443]
   Hashes of expected file:
    - Filesize:230074 [weak]
    - SHA256:16fffd7bd37fed9efc68f8a087142f42f47afa3596041f72cd08f2e9aa5c03c8
    - SHA1:1271f269071261a2e0cd132df5396c45b223eab6 [weak]
    - MD5Sum:2963a72fec35e1e75d25d2b4918596dd [weak]
   Release file created at: Tue, 02 Feb 2021 17:08:28 +0000
E: Failed to fetch https://repo.huaweicloud.com/postgresql/repos/apt/dists/bionic-pgdg/main/binary-amd64/Packages.bz2  
E: Some index files failed to download. They have been ignored, or old ones used instead.

/etc/apt/sources.list.d/pgdg.list内容:

deb https://repo.huaweicloud.com/postgresql/repos/apt/ bionic-pgdg main

建议方案：

检查postgresql的ubuntu 18.04镜像