On 8/29/20 9:50 PM, Tom Lane wrote:
Years ago (when I was still at Salesforce, IIRC, so ~5 years) we had
some discussions about making it possible for pg_dump and/or pg_upgrade
to propagate stats data forward to the new database. There is at least
one POC patch in the archives for doing that by dumping the stats data
wrapped in a function call, where the target database's version of the
function would be responsible for adapting the data if necessary, or
maybe just discarding it if it couldn't adapt. We seem to have lost
interest but it still seems like something worth pursuing. I'd guess
that if such infrastructure existed it could be helpful for this.
Thanks for this helpful feedback.
I found several threads related to the problem [1-3].
I agreed that this task needs to implement an API for
serialization/deserialization of statistics:
pg_load_relation_statistics(json_string text);
pg_get_relation_statistics(relname text);
We can use a version number for resolving conflicts with different
statistics implementations.
"Load" function will validate the values[] anyarray while deserializing
the input json string to the datatype of the relation column.
Maybe I didn't feel all the problems of this task?
1. https://www.postgresql.org/message-id/flat/724322880.K8vzik8zPz%40abook
2.
https://www.postgresql.org/message-id/flat/CAAZKuFaWdLkK8eozSAooZBets9y_mfo2HS6urPAKXEPbd-JLCA%40mail.gmail.com
3.
https://www.postgresql.org/message-id/flat/GNELIHDDFBOCMGBFGEFOOEOPCBAA.chriskl%40familyhealth.com.au
--
regards,
Andrey Lepikhov
Postgres Professional
