adapter: expose Materialize version in mz_version parameter #17024
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This commit exposes the Materialize-specific information in a new
`mz_version` parameter, as in:
materialize=> show mz_version;
mz_version
-------------------------
v0.39.0-dev (73f6bed)
(1 row)
The `mz_version` parameter is additionally added to the parameter set
that is automatically sent to the client during part of startup. This
approach comes from CockroachDB, and allows clients to easily detect
whether they're talking to Materialize or PostgreSQL without incurring
an additional roundtrip.
I already have a PR out to sqlx [0] that uses this feature to
automatically disable PostgreSQL-specific features that Materialize does
not support.
The version string matches the output of the `mz_version()` function.
The implementation is somewhat irritating, as it requires plumbing the
`BuildInfo` from the adapter into each session. Doesn't turn out too
complicated, though, now that it's all written out.
[0]: launchbadge/sqlx#2282
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maddyblue
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Jan 9, 2023
| @@ -399,6 +402,7 @@ static EMIT_TRACE_ID_NOTICE: ServerVar<bool> = ServerVar { | |||
| #[derive(Debug)] | |||
| pub struct SessionVars { | |||
| application_name: SessionVar<str>, | |||
| build_info: &'static BuildInfo, | |||
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Should this go on SystemVars instead?
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System vars can be set with ALTER SYSTEM SET which is not what we want here. It's kinda a funny split (probably system vars and server/session vars should be unified somehow), but for now this is the right spot!
maddyblue
approved these changes
Jan 9, 2023
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This commit exposes the Materialize-specific information in a new
mz_versionparameter, as in:The
mz_versionparameter is additionally added to the parameter set that is automatically sent to the client during part of startup. This approach comes from CockroachDB, and allows clients to easily detect whether they're talking to Materialize or PostgreSQL without incurring an additional roundtrip.I already have a PR out to sqlx 0 that uses this feature to automatically disable PostgreSQL-specific features that Materialize does not support.
The version string matches the output of the
mz_version()function.The implementation is somewhat irritating, as it requires plumbing the
BuildInfofrom the adapter into each session. Doesn't turn out too complicated, though, now that it's all written out.Motivation
Checklist
This PR has adequate test coverage / QA involvement has been duly considered.
This PR evolves an existing
$T ⇔ Proto$Tmapping (possibly in a backwards-incompatible way) and therefore is tagged with aT-protolabel.If this PR will require changes to cloud orchestration, there is a
companion cloud PR to account for those changes that is tagged with
the release-blocker label (example).
This PR includes the following user-facing behavior changes:
mz_versionsystem configuration parameter, which reports the Materialize version information. The value of this parameter is the same as the value returned by the existingmz_version()function. The parameter form can be more convenient for downstream applications.