Robert Haas <robertmh...@gmail.com> writes: > In more normal cases, however, the system can (and probably should) > figure out what was intended by choosing the *shortest* path to get to > the intended version. For example, if someone ships 1.0, 1.0--1.1, > 1.1, and 1.1--1.2, the system should choose to run 1.1 and then > 1.1--1.2, not 1.0 and then 1.0--1.1 and then 1.1--1.2. But that can > be automatic: only if there are two paths of equal length (as in the > example in the previous paragraph) do we need help from the user to > figure out what to do.
Yeah. > We should also consider the possibility of a user trying to > deliberately install and older release. For example, if the user has > 1.0, 1.0--1.1, 1.1, 1.1--1.2, and 1.2--1.0 (a downgrade script) with > default_full_version = 1.2, an attempt to install 1.0 should run just > the 1.0 script, NOT 1.2 and then 1.2--1.0. In what I did, if you want version 1.0 and we have a script --1.0.sql around, then we just use that script, never kicking the path chooser. The path chooser at CREATE EXTENSION time is only execised when we don't have a direct script to support that specific version you're asking. > Putting all that together, I'm inclined to suggest that what we really > need is a LIST of version numbers, rather than just one. If there one > path to the version we're installing is shorter than any other, we > choose that, period. If there are multiple paths of equal length, we That's what Jeff did propose, yes. > break the tie by choosing which version number appears first in the > aforementioned list. If that still doesn't break the tie, either > because none of the starting points are mentioned in that list or > because there are multiple equal-length paths starting in the same > place, we give up and emit an error. Jeff also did mention about tiebreakers without entering into any level of details. We won't be able to just use default_version as the tiebreaker list here, because of the following example: default_version = 1.2, 1.0 create extension foo version '1.1'; With such a setup it would prefer 1.2--1.1 to 1.0--1.1, which doesn't look like what we want. Instead, we want default_version = 1.2 create_from_version_candidates = 1.0 create extension foo version '1.1'; Then the tie breaker is the 1.0 in "create_from_version_candidates" so we would run foo--1.0.sql and then foo--1.0--1.1.sql. Comments? Baring objections, I'm going to prepare a new branch to support developping that behavior against only file based extensions, and submit a spin-off patch to the current CF entry. Regards, -- Dimitri Fontaine http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
