Re: BUG #15896: pg_upgrade from 10-or-earlier: TRAP: FailedAssertion(»!(metad->btm_version >= 3)«

Adding Peter G. to CC.

On 2019-Jul-05, PG Bug reporting form wrote:

> When pg_upgrading from 10-or-earlier to 12beta2 or 13devel, an assertion is
> raised. (Spotted by Debian's postgresql-common upgrade tests. Previously
> missed because we were only testing version+1 upgrades.)
> 
> TRAP: FailedAssertion(»!(metad->btm_version >= 3)«, Datei:
> »/build/postgresql-12-3URvLF/postgresql-12-12~beta2/build/../src/backend/access/nbtree/nbtpage.c«,
> Zeile: 665)

Seems that _bt_getrootheight is too optimistic about the metapage
version it'll find.  I suppose this could be handled by just not caching
the metapage if it is of the old version ... or maybe by calling
_bt_upgrademetapage().

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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