Re: pg_upgrading to 10.1 corrupts (varchar,varchar) UNIQUE indices

rihad wrote:
> Hi there, this is a reproducible error. We recently pg_upgraded our 
> production database to 10.1 from 9.6.6. The upgrade runs fine with the 
> suggestion to analyze all data.

[...]

> Trying to find data using the specified indices fails to find matching rows:

[...]

> reindexing the table fixes the issue:

Did you also upgrade the operating system or at least libc?

Then the problem could come from a modified collation.
Compare https://www.postgresql.org/message-id/CB4D1C6BAA80CF146CB0D4F2%40eje.credativ.lan

Yours,
Laurenz Albe