Function BuildRoleInheritanceTable

pg_documentdb/src/commands/roles.c:1444–1620

* BuildRoleInheritanceTable fetches all roles and their parent relationships * and builds an in-memory hash table for efficient lookups. * * Role System Overview: * - pg_roles contains information about both user roles and groups. * - pg_auth_members tracks role membership: which roles are members of which * parent roles. Note that parent roles can themselves have parents * * Query Logic

 *   - parentRoles: List of internal parent role names this role inherits from
 */
static HTAB *
BuildRoleInheritanceTable(void)
{
	HASHCTL hashCtl;
	memset(&hashCtl, 0, sizeof(hashCtl));
	hashCtl.keysize = NAMEDATALEN;
	hashCtl.entrysize = sizeof(RoleParentEntry);
	hashCtl.hcxt = CurrentMemoryContext;

	HTAB *roleInheritanceTable = hash_create("RoleInheritanceTable",
											 64,
											 &hashCtl,
											 HASH_ELEM | HASH_STRINGS | HASH_CONTEXT);

	/*
	 * Query returns all built-in and custom roles with their direct parent roles, all in internal role names.
	 */
	const char *inheritanceQuery = FormatSqlQuery(
		"SELECT ARRAY_AGG(%s.row_get_bson(r)) FROM ("
		"  SELECT "
		"    child.rolname::text AS child_role, "
		"    ARRAY_AGG(parent.rolname::text) "
		"      FILTER (WHERE parent.rolname IS NOT NULL AND parent.oid >= %d) AS parent_roles "
		"  FROM pg_roles child "
		"  LEFT JOIN pg_auth_members am ON am.member = child.oid "
		"  LEFT JOIN pg_roles parent ON parent.oid = am.roleid "
		"  WHERE child.oid >= %d "
		"    AND (NOT child.rolcanlogin OR child.rolname = '%s') "
		"  GROUP BY child.rolname"
		") r;",
		CoreSchemaName,
		FirstNormalObjectId,
		FirstNormalObjectId,
		ApiRootInternalRole);

	bool readOnly = true;
	bool isNull = false;

	Datum resultDatum = ExtensionExecuteQueryViaSPI(inheritanceQuery, readOnly,
													SPI_OK_SELECT, &isNull);

	/*
	 * If result is NULL, no roles matched the query, which should never happen.
	 */
	if (isNull)
	{
		ereport(ERROR, (errcode(ERRCODE_DOCUMENTDB_INTERNALERROR),
						errmsg("Role inheritance query returned NULL result.")));
	}

	ArrayType *resultArray = DatumGetArrayTypeP(resultDatum);

	Datum *rowDatums;
	bool *rowNulls;
	int rowCount;
	deconstruct_array(resultArray, BsonTypeId(), -1, false, TYPALIGN_INT,
					  &rowDatums, &rowNulls, &rowCount);