Endpoints SQL translator emits BigQuery backticks on PostgreSQL backend (OSS v1.36.1 through v1.42.0)

[dainjaruss]

Bug

Logflare OSS v1.36.1 (and verified byte-identical through v1.42.0) — the /endpoints page's SQL translator rewrites friendly source-name references into BigQuery-style backtick-quoted identifiers regardless of backend. When the backend is PostgreSQL, the resulting query errors with %Postgrex.Error{... message: "syntax error at or near \"""...}`.

Code path

Logflare.Endpoints.Query.infer_language_from_backend/1 returns :pg_sql only when a Postgres backend is explicitly selected on the endpoint AND Supabase mode is OFF. Endpoint defaults to :bq_sql regardless of deployment mode.

Workaround

Stick with /query page (doesn't run the broken translator) and save URL as a browser bookmark.

Attempted fix that regresses worse

Setting LOGFLARE_FEATURE_FLAG_OVERRIDE=multibackend=true,endpointbackendselection=true is supposed to surface a Backend selector. In v1.36.1 the toggle removes the query SQL field entirely from the endpoint create form.

Suggested upstream change

The endpoint create form should default language: :pg_sql when the deployment is single-tenant PG, not require explicit per-endpoint backend selection that's gated behind a buggy flag.

Evidence / full diagnostic

Full diagnostic + code-path analysis in the Paari project's runbook:
https://github.com/dainjaruss/paari/blob/main/docs/runbooks/logflare.md#the-endpoints-pg-translator-bug-logflare-oss-bug-upstream-unfixed-as-of-v1420

(Quote of the section at time of filing is included below for permanence.)

---

The /endpoints PG-translator bug (Logflare OSS bug, upstream unfixed as of v1.42.0)

The Endpoints UI runs a pre-execution SQL translator that rewrites friendly source-name references into BigQuery-style backtick-quoted internal identifiers regardless of the configured backend. When the backend is PostgreSQL, the resulting query errors:

%Postgrex.Error{... message: "syntax error at or near \"`\"" ...}
... query: "... FROM `.1_default.5bf225a1_037e_4092_8899_c7515e503bce` ..."

The translator emits BQ backticks because the endpoint defaults to language: :bq_sql. Code path: Logflare.Endpoints.Query.infer_language_from_backend/1 returns :pg_sql only when a Postgres backend is explicitly selected on the endpoint AND Supabase mode is OFF.

Workaround on v1.36.1: stick with the /query page and save the URL as a browser bookmark. The /query page does NOT run the broken translator. You lose HTTP-callable named endpoints but gain working queries.

Attempted fix that regresses worse: setting LOGFLARE_FEATURE_FLAG_OVERRIDE=multibackend=true,endpointbackendselection=true is supposed to surface a Backend selector in the endpoint create form. In practice on v1.36.1 the toggle removes the query SQL field entirely from the form (form layout regression). Revert with LOGFLARE_FEATURE_FLAG_OVERRIDE=multibackend=true (single flag) and recreate the logflare container. Browser hard-refresh required afterward.

Code-side analysis (from a v1.36.1→v1.42.0 changelog audit on 2026-05-26): the PG translator code path is byte-identical between v1.36.1 and v1.42.0. No upstream release fixes this. Upstream issue to file: the endpoint create form should default language: :pg_sql when the deployment is single-tenant PG, not require explicit per-endpoint backend selection that's gated behind a broken flag.

---

This was filed from Paari (private family photo app) which runs self-hosted single-tenant OSS Logflare on Postgres. See related Paari issue: https://github.com/dainjaruss/paari/issues/980