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docs(typelayer): tenants on one ClickHouse line must report the same zone spelling (UTC ≠ Etc/UTC) #717
Description
Activity
Correction: comparing zone names is the safe behaviour, not a bug.
This was measured on the 26.8.15.10 chtypes artifact: for a bare
DateTimecolumn,DEFAULT timezoneOf(ts)stores the zone spelling the library was opened with, verbatim.UTCstores"UTC"andEtc/UTCstores"Etc/UTC", and the same goes forUS/PacificvsAmerica/Los_Angeles. A server presumably stores its own configured spelling (inferred).So if a tenant whose server reports
Etc/UTCwere served by a line opened asUTC, atimezoneOf-style DEFAULT would publish and insert"UTC"where the server stores"Etc/UTC". That is a silent wrong value. Refusing the tenant on a spelling mismatch avoids it.What is left is documentation: tenants served by one process on one ClickHouse line must report the same zone spelling, not just the same zone, so give servers one consistent spelling. Retitled to match. Per-call or per-schema zones are tracked upstream in chtypes, and would remove the constraint.
- changed the title
[-]bug(typelayer): the zone check compares names, so a tenant reporting Etc/UTC is refused by a process opened as UTC[/-][+]docs(typelayer): tenants on one ClickHouse line must report the same zone spelling (UTC ≠ Etc/UTC)[/+]on Oct 1, 2026 Update from #712's move to chtypes 1.0: the per-line zone check this issue describes is gone. A process now has one image zone, taken from the first tenant actually served, and every other tenant's server zone is passed per call when it differs.
How the spelling case looks now (inferred from
internal/typelayer/zone.go, not reproduced):- A tenant reporting
Etc/UTCin a process whose image zone isUTCis no longer refused whole. - Its name differs from the image zone's, so it counts as a different zone.
- Its zone is passed per call. That is harmless, because literals and parsing come out the same.
- The narrowed per-table rule refuses its tables that pair a zone-less
DateTimecolumn with aDEFAULT/MATERIALIZED/ALIAS/EPHEMERALexpression, although both names resolve to the same zone.
Related: #726 (which tenant sets the image zone).
- A tenant reporting
Found while reviewing the type layer in draft PR #712 (branch
chtypes-v2).Problem. The server-zone check compares zone name strings. A tenant whose server reports
Etc/UTCis refused by a process that opened its line asUTC, although both are the same zone. Inferred from reading the comparison; the refusal has not been reproduced.Repro (to be confirmed). Run two ClickHouse servers, one with
timezoneset toUTCand one toEtc/UTC, register both as tenants in one process.Expected: zones that resolve to the same offsets are accepted.