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42P06 — Duplicate schema

PostgreSQL SQLSTATE 42P06: Duplicate schema (duplicate_schema), source-backed diagnosis and recovery guidance.

42P06 — Duplicate schema

At a glance

42P06 (duplicate_schema) is a schema-definition collision. Plain CREATE SCHEMA errors; IF NOT EXISTS can emit NOTICE and continue, but that conditional path only skips creation and does not reconcile the existing schema.

Field Value
SQLSTATE 42P06
Condition duplicate_schema
Status active
Known present by 7.4
Locked snapshots 9.0.23, 9.1.24, 9.2.24, 9.3.25, 9.4.26, 9.5.25, 9.6.24, 10.23, 11.22, 12.22, 13.23, 14.24, 15.19, 16.15, 17.11, 18.6, 19beta3
Macros ERRCODE_DUPLICATE_SCHEMA
Aliases —

Meaning

NamespaceCreate reports ERROR schema "%s" already exists when the pg_namespace name lookup finds a row. CREATE SCHEMA IF NOT EXISTS checks the same namespace and reports NOTICE schema "%s" already exists, skipping before creation. Both messages identify the schema itself, not a relation inside it. The fixed command path performs the creation-permission checks before the conditional skip; the NOTICE is not an ownership or definition comparison.

Diagnosis

Resolve the target database and schema, then inspect pg_namespace.nspname, owner/ACL, contents, and the exact migration statement. Preserve severity: NOTICE is conditional behavior and lets the command continue; plain CREATE’s ERROR aborts an explicit transaction. Do not infer that a NOTICE schema has the requested owner, grants, extensions, tables, or migration version.

Response

Reuse only when owner, privileges, and contents meet the application contract. IF NOT EXISTS does not verify or reconcile those properties; follow it with explicit ownership/grant or migration checks when required. Do not drop a schema merely to pass a migration. If plain CREATE produced an ERROR in an explicit transaction, roll back to a suitable savepoint or roll back the transaction before continuing.

Messages

The selected variants are schema "%s" already exists (explicit ERROR) and schema "%s" already exists, skipping (explicit NOTICE). %s is the dynamic schema name; neither message certifies the existing schema’s owner or definition.

Versions

From 7.4 through 18.6 and 19beta3; that catalogue range is not a precise introduction claim. The selected ERROR and NOTICE branches are fixed 18.6 source paths, and runtime was not run.

Sources

  • src.errcodes.42P06.18.6 — src/backend/utils/errcodes.txt line 382, fixed at 724edf9bde9d356724ad384a2e196edc3c9f80f7; SHA-256 6e8de346643ba84aa3c9c6a73360acfc7b2dfb89162c06c08ce9bf5bcd5bbcba (source).

  • src.call.42P06.4d5505b63e38ef1b25836623 — src/backend/catalog/pg_namespace.c lines 62-64, fixed at 724edf9bde9d356724ad384a2e196edc3c9f80f7; SHA-256 89675ba1bb9c531ab4f43db8a6f7cac00956561b342e42ea6eaae6b8d0b50d78 (source).

  • src.call.42P06.373538bec86ad8eedfce8d7a — src/backend/commands/schemacmds.c lines 132-135, fixed at 724edf9bde9d356724ad384a2e196edc3c9f80f7; SHA-256 5fd5f43dce5f36f06ed390014c06f244564072227d25a22735f594d2170626b1 (source).

  • src.calls.REL_18_6.42P06 — resolved core call groups; SHA-256 9ee8a0e81d8f0825c5c1ae45583439859a26e602bdd4ce2f2a62aa278867ccbf.

  • authored evidence — source claims, message roles, and runtime boundary.