2BP01

At a glance

2BP01 means a DROP or related catalog operation would remove an object that other database objects still require. The useful repair is dependency-aware: identify the dependent object, decide whether it should be removed or retained, and only then retry the original operation.

Meaning

The dependency walker emits 2BP01 for a blocked object operation. In the representative path, a view depends on a table, so DROP TABLE cannot proceed. The primary message, DETAIL, and CASCADE hint are dynamically assembled from object descriptions and the dependency graph. 2BP01 is about dependent objects; 2B000 is a separate dependent-privilege-descriptor condition.

Diagnosis

Capture SQLSTATE, primary message, DETAIL, and HINT together. The DETAIL identifies the dependent view in the selected path. Inspect the view definition and dependency metadata before choosing a repair; pg_depend and pg_get_viewdef() help explain why the object is retained. In the selected explicit BEGIN block, this ERROR puts the connection in INERROR until ROLLBACK; an autocommit statement has no surrounding block to preserve. Catalog queries issued through the failed explicit block will not provide a clean diagnosis.

Response

Rollback the failed explicit transaction. If the view is intentionally disposable, drop that view first and then the table; if it is part of the schema contract, preserve it and choose a different migration. CASCADE is a deliberate request to remove dependent objects and can exceed the intended change, so the HINT is not an instruction to apply it automatically. After a dependency-aware repair, rerun the complete DDL plan and verify the surviving objects.

Messages

The selected source branch uses cannot drop %s because other objects depend on it, a dynamic internal DETAIL, and Use DROP ... CASCADE to drop the dependent objects too. The object descriptions and dependency list are runtime values; do not treat the DETAIL as a stable single-object template or assume every 2BP01 path has this exact wording.

Representative case

The runner reads this dependency sequence from verify/cases/2BP01/snippets.json (SHA-256 899e4fd9fb002fc293bd9efee0204e4f2622968c6d9460ad05eb9a0ebd3bac69). It uses an explicit BEGIN/ROLLBACK for the failed DROP and then removes the known view before its table, without CASCADE. See the public case export and structured evidence.

CREATE TABLE base_items(id integer PRIMARY KEY, payload text NOT NULL);
CREATE VIEW dependent_view AS SELECT id, payload FROM base_items;
BEGIN;
DROP TABLE base_items;
ROLLBACK;
DROP VIEW dependent_view;
DROP TABLE base_items;
SELECT to_regclass('base_items'), to_regclass('dependent_view');

The registry names are qualified by the runner inside a private schema. The final to_regclass check returns two nulls, proving that the intended objects were removed rather than silently cascading through an unknown graph.

The selected case observed 2BP01 on PostgreSQL 18.6 and 10.21. DROP TABLE reported the dependent view in DETAIL and suggested CASCADE; the explicit block was INERROR, ROLLBACK restored IDLE, and intentionally dropping the view first allowed the table to be removed.

Versions

The catalogue records this condition from the early historical boundary through the formal snapshots. The fixed 18.6 source includes dependency, shared-dependency, role, privilege, typed-table, and tablespace branches; the runtime case covers one ordinary view-to-table dependency on 18.6 and 10.21. Do not infer that a CASCADE hint is equally safe for all branches.

Related

Compare 2B000 dependent privilege descriptors and 42P01 undefined table when a DROP or dependency report names the wrong layer.

Sources

• src.errcodes.18.6 (SHA-256 6e8de346643ba84aa3c9c6a73360acfc7b2dfb89162c06c08ce9bf5bcd5bbcba)
• src.dependency.18.6 (SHA-256 1878f848dae03e08424a47a09508f3443227ad67c4bc5e0aba3ec9655d015b74)
• DROP TABLE documentation · local call scan src.calls.REL_18_6 (SHA-256 9ee8a0e81d8f0825c5c1ae45583439859a26e602bdd4ce2f2a62aa278867ccbf)

Source evidence

Evidence belongs to the frozen source and runtime versions listed here. It is not a runtime verification of the selected manual version.

• src/backend/utils/errcodes.txt · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• raw/calls/REL_18_6.jsonl · ·
• src/backend/catalog/dependency.c · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7
• doc/src/sgml/ref/drop_table.sgml · REL_18_6 ·
  724edf9bde9d356724ad384a2e196edc3c9f80f7

Message templates

cannot drop %s because other objects depend on it

%s (dynamic internal detail)

Use DROP ... CASCADE to drop the dependent objects too.

Reproduction & repair cases

Recorded runtime evidence

{
  "repair": {
    "remaining_relations": [
      null,
      null
    ]
  },
  "primary": "cannot drop table c2bp01_dependent_object_drop_recovery.base_items because other objects depend on it",
  "severity": "ERROR",
  "sqlstate": "2BP01",
  "statuses": {
    "after_error": "INERROR",
    "after_repair": "IDLE",
    "after_rollback": "IDLE"
  },
  "connection_autocommit": true
}

{
  "repair": {
    "remaining_relations": [
      null,
      null
    ]
  },
  "primary": "cannot drop table c2bp01_dependent_object_drop_recovery.base_items because other objects depend on it",
  "severity": "ERROR",
  "sqlstate": "2BP01",
  "statuses": {
    "after_error": "INERROR",
    "after_repair": "IDLE",
    "after_rollback": "IDLE"
  },
  "connection_autocommit": true
}