dropcmds.c

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/*-------------------------------------------------------------------------
 *
 * dropcmds.c
 *    handle various "DROP" operations
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/commands/dropcmds.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/table.h"
#include "access/xact.h"
#include "catalog/dependency.h"
#include "catalog/namespace.h"
#include "catalog/objectaddress.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_proc.h"
#include "commands/defrem.h"
#include "miscadmin.h"
#include "parser/parse_type.h"
#include "utils/acl.h"
#include "utils/lsyscache.h"
 
 
static void does_not_exist_skipping(ObjectType objtype,
                                    Node *object);
static bool owningrel_does_not_exist_skipping(List *object,
                                              const char **msg, char **name);
static bool schema_does_not_exist_skipping(List *object,
                                           const char **msg, char **name);
static bool type_in_list_does_not_exist_skipping(List *typenames,
                                                 const char **msg, char **name);
 
 
/*
 * Drop one or more objects.
 *
 * We don't currently handle all object types here.  Relations, for example,
 * require special handling, because (for example) indexes have additional
 * locking requirements.
 *
 * We look up all the objects first, and then delete them in a single
 * performMultipleDeletions() call.  This avoids unnecessary DROP RESTRICT
 * errors if there are dependencies between them.
 */
void
RemoveObjects(DropStmt *stmt)
{
    ObjectAddresses *objects;
    ListCell   *cell1;
 
    objects = new_object_addresses();
 
    foreach(cell1, stmt->objects)
    {
        ObjectAddress address;
        Node       *object = lfirst(cell1);
        Relation    relation = NULL;
        Oid         namespaceId;
 
        /* Get an ObjectAddress for the object. */
        address = get_object_address(stmt->removeType,
                                     object,
                                     &relation,
                                     AccessExclusiveLock,
                                     stmt->missing_ok);
 
        /*
         * Issue NOTICE if supplied object was not found.  Note this is only
         * relevant in the missing_ok case, because otherwise
         * get_object_address would have thrown an error.
         */
        if (!OidIsValid(address.objectId))
        {
            Assert(stmt->missing_ok);
            does_not_exist_skipping(stmt->removeType, object);
            continue;
        }
 
        /*
         * Although COMMENT ON FUNCTION, SECURITY LABEL ON FUNCTION, etc. are
         * happy to operate on an aggregate as on any other function, we have
         * historically not allowed this for DROP FUNCTION.
         */
        if (stmt->removeType == OBJECT_FUNCTION)
        {
            if (get_func_prokind(address.objectId) == PROKIND_AGGREGATE)
                ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is an aggregate function",
                                NameListToString(castNode(ObjectWithArgs, object)->objname)),
                         errhint("Use DROP AGGREGATE to drop aggregate functions.")));
        }
 
        /* Check permissions. */
        namespaceId = get_object_namespace(&address);
        if (!OidIsValid(namespaceId) ||
            !object_ownercheck(NamespaceRelationId, namespaceId, GetUserId()))
            check_object_ownership(GetUserId(), stmt->removeType, address,
                                   object, relation);
 
        /*
         * Make note if a temporary namespace has been accessed in this
         * transaction.
         */
        if (OidIsValid(namespaceId) && isTempNamespace(namespaceId))
            MyXactFlags |= XACT_FLAGS_ACCESSEDTEMPNAMESPACE;
 
        /* Release any relcache reference count, but keep lock until commit. */
        if (relation)
            table_close(relation, NoLock);
 
        add_exact_object_address(&address, objects);
    }
 
    /* Here we really delete them. */
    performMultipleDeletions(objects, stmt->behavior, 0);
 
    free_object_addresses(objects);
}
 
/*
 * owningrel_does_not_exist_skipping
 *      Subroutine for RemoveObjects
 *
 * After determining that a specification for a rule or trigger returns that
 * the specified object does not exist, test whether its owning relation, and
 * its schema, exist or not; if they do, return false --- the trigger or rule
 * itself is missing instead.  If the owning relation or its schema do not
 * exist, fill the error message format string and name, and return true.
 */
static bool
owningrel_does_not_exist_skipping(List *object, const char **msg, char **name)
{
    List       *parent_object;
    RangeVar   *parent_rel;
 
    parent_object = list_copy_head(object, list_length(object) - 1);
 
    if (schema_does_not_exist_skipping(parent_object, msg, name))
        return true;
 
    parent_rel = makeRangeVarFromNameList(parent_object);
 
    if (!OidIsValid(RangeVarGetRelid(parent_rel, NoLock, true)))
    {
        *msg = gettext_noop("relation \"%s\" does not exist, skipping");
        *name = NameListToString(parent_object);
 
        return true;
    }
 
    return false;
}
 
/*
 * schema_does_not_exist_skipping
 *      Subroutine for RemoveObjects
 *
 * After determining that a specification for a schema-qualifiable object
 * refers to an object that does not exist, test whether the specified schema
 * exists or not.  If no schema was specified, or if the schema does exist,
 * return false -- the object itself is missing instead.  If the specified
 * schema does not exist, fill the error message format string and the
 * specified schema name, and return true.
 */
static bool
schema_does_not_exist_skipping(List *object, const char **msg, char **name)
{
    RangeVar   *rel;
 
    rel = makeRangeVarFromNameList(object);
 
    if (rel->schemaname != NULL &&
        !OidIsValid(LookupNamespaceNoError(rel->schemaname)))
    {
        *msg = gettext_noop("schema \"%s\" does not exist, skipping");
        *name = rel->schemaname;
 
        return true;
    }
 
    return false;
}
 
/*
 * type_in_list_does_not_exist_skipping
 *      Subroutine for RemoveObjects
 *
 * After determining that a specification for a function, cast, aggregate or
 * operator returns that the specified object does not exist, test whether the
 * involved datatypes, and their schemas, exist or not; if they do, return
 * false --- the original object itself is missing instead.  If the datatypes
 * or schemas do not exist, fill the error message format string and the
 * missing name, and return true.
 *
 * First parameter is a list of TypeNames.
 */
static bool
type_in_list_does_not_exist_skipping(List *typenames, const char **msg,
                                     char **name)
{
    ListCell   *l;
 
    foreach(l, typenames)
    {
        TypeName   *typeName = lfirst_node(TypeName, l);
 
        if (typeName != NULL)
        {
            if (!OidIsValid(LookupTypeNameOid(NULL, typeName, true)))
            {
                /* type doesn't exist, try to find why */
                if (schema_does_not_exist_skipping(typeName->names, msg, name))
                    return true;
 
                *msg = gettext_noop("type \"%s\" does not exist, skipping");
                *name = TypeNameToString(typeName);
 
                return true;
            }
        }
    }
 
    return false;
}
 
/*
 * does_not_exist_skipping
 *      Subroutine for RemoveObjects
 *
 * Generate a NOTICE stating that the named object was not found, and is
 * being skipped.  This is only relevant when "IF EXISTS" is used; otherwise,
 * get_object_address() in RemoveObjects would have thrown an ERROR.
 */
static void
does_not_exist_skipping(ObjectType objtype, Node *object)
{
    const char *msg = NULL;
    char       *name = NULL;
    char       *args = NULL;
 
    switch (objtype)
    {
        case OBJECT_ACCESS_METHOD:
            msg = gettext_noop("access method \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
        case OBJECT_TYPE:
        case OBJECT_DOMAIN:
            {
                TypeName   *typ = castNode(TypeName, object);
 
                if (!schema_does_not_exist_skipping(typ->names, &msg, &name))
                {
                    msg = gettext_noop("type \"%s\" does not exist, skipping");
                    name = TypeNameToString(typ);
                }
            }
            break;
        case OBJECT_COLLATION:
            if (!schema_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("collation \"%s\" does not exist, skipping");
                name = NameListToString(castNode(List, object));
            }
            break;
        case OBJECT_CONVERSION:
            if (!schema_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("conversion \"%s\" does not exist, skipping");
                name = NameListToString(castNode(List, object));
            }
            break;
        case OBJECT_SCHEMA:
            msg = gettext_noop("schema \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
        case OBJECT_STATISTIC_EXT:
            if (!schema_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("statistics object \"%s\" does not exist, skipping");
                name = NameListToString(castNode(List, object));
            }
            break;
        case OBJECT_TSPARSER:
            if (!schema_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("text search parser \"%s\" does not exist, skipping");
                name = NameListToString(castNode(List, object));
            }
            break;
        case OBJECT_TSDICTIONARY:
            if (!schema_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("text search dictionary \"%s\" does not exist, skipping");
                name = NameListToString(castNode(List, object));
            }
            break;
        case OBJECT_TSTEMPLATE:
            if (!schema_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("text search template \"%s\" does not exist, skipping");
                name = NameListToString(castNode(List, object));
            }
            break;
        case OBJECT_TSCONFIGURATION:
            if (!schema_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("text search configuration \"%s\" does not exist, skipping");
                name = NameListToString(castNode(List, object));
            }
            break;
        case OBJECT_EXTENSION:
            msg = gettext_noop("extension \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
        case OBJECT_FUNCTION:
            {
                ObjectWithArgs *owa = castNode(ObjectWithArgs, object);
 
                if (!schema_does_not_exist_skipping(owa->objname, &msg, &name) &&
                    !type_in_list_does_not_exist_skipping(owa->objargs, &msg, &name))
                {
                    msg = gettext_noop("function %s(%s) does not exist, skipping");
                    name = NameListToString(owa->objname);
                    args = TypeNameListToString(owa->objargs);
                }
                break;
            }
        case OBJECT_PROCEDURE:
            {
                ObjectWithArgs *owa = castNode(ObjectWithArgs, object);
 
                if (!schema_does_not_exist_skipping(owa->objname, &msg, &name) &&
                    !type_in_list_does_not_exist_skipping(owa->objargs, &msg, &name))
                {
                    msg = gettext_noop("procedure %s(%s) does not exist, skipping");
                    name = NameListToString(owa->objname);
                    args = TypeNameListToString(owa->objargs);
                }
                break;
            }
        case OBJECT_ROUTINE:
            {
                ObjectWithArgs *owa = castNode(ObjectWithArgs, object);
 
                if (!schema_does_not_exist_skipping(owa->objname, &msg, &name) &&
                    !type_in_list_does_not_exist_skipping(owa->objargs, &msg, &name))
                {
                    msg = gettext_noop("routine %s(%s) does not exist, skipping");
                    name = NameListToString(owa->objname);
                    args = TypeNameListToString(owa->objargs);
                }
                break;
            }
        case OBJECT_AGGREGATE:
            {
                ObjectWithArgs *owa = castNode(ObjectWithArgs, object);
 
                if (!schema_does_not_exist_skipping(owa->objname, &msg, &name) &&
                    !type_in_list_does_not_exist_skipping(owa->objargs, &msg, &name))
                {
                    msg = gettext_noop("aggregate %s(%s) does not exist, skipping");
                    name = NameListToString(owa->objname);
                    args = TypeNameListToString(owa->objargs);
                }
                break;
            }
        case OBJECT_OPERATOR:
            {
                ObjectWithArgs *owa = castNode(ObjectWithArgs, object);
 
                if (!schema_does_not_exist_skipping(owa->objname, &msg, &name) &&
                    !type_in_list_does_not_exist_skipping(owa->objargs, &msg, &name))
                {
                    msg = gettext_noop("operator %s does not exist, skipping");
                    name = NameListToString(owa->objname);
                }
                break;
            }
        case OBJECT_LANGUAGE:
            msg = gettext_noop("language \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
        case OBJECT_CAST:
            {
                if (!type_in_list_does_not_exist_skipping(list_make1(linitial(castNode(List, object))), &msg, &name) &&
                    !type_in_list_does_not_exist_skipping(list_make1(lsecond(castNode(List, object))), &msg, &name))
                {
                    /* XXX quote or no quote? */
                    msg = gettext_noop("cast from type %s to type %s does not exist, skipping");
                    name = TypeNameToString(linitial_node(TypeName, castNode(List, object)));
                    args = TypeNameToString(lsecond_node(TypeName, castNode(List, object)));
                }
            }
            break;
        case OBJECT_TRANSFORM:
            if (!type_in_list_does_not_exist_skipping(list_make1(linitial(castNode(List, object))), &msg, &name))
            {
                msg = gettext_noop("transform for type %s language \"%s\" does not exist, skipping");
                name = TypeNameToString(linitial_node(TypeName, castNode(List, object)));
                args = strVal(lsecond(castNode(List, object)));
            }
            break;
        case OBJECT_TRIGGER:
            if (!owningrel_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("trigger \"%s\" for relation \"%s\" does not exist, skipping");
                name = strVal(llast(castNode(List, object)));
                args = NameListToString(list_copy_head(castNode(List, object),
                                                       list_length(castNode(List, object)) - 1));
            }
            break;
        case OBJECT_POLICY:
            if (!owningrel_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("policy \"%s\" for relation \"%s\" does not exist, skipping");
                name = strVal(llast(castNode(List, object)));
                args = NameListToString(list_copy_head(castNode(List, object),
                                                       list_length(castNode(List, object)) - 1));
            }
            break;
        case OBJECT_EVENT_TRIGGER:
            msg = gettext_noop("event trigger \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
        case OBJECT_RULE:
            if (!owningrel_does_not_exist_skipping(castNode(List, object), &msg, &name))
            {
                msg = gettext_noop("rule \"%s\" for relation \"%s\" does not exist, skipping");
                name = strVal(llast(castNode(List, object)));
                args = NameListToString(list_copy_head(castNode(List, object),
                                                       list_length(castNode(List, object)) - 1));
            }
            break;
        case OBJECT_FDW:
            msg = gettext_noop("foreign-data wrapper \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
        case OBJECT_FOREIGN_SERVER:
            msg = gettext_noop("server \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
        case OBJECT_OPCLASS:
            {
                List       *opcname = list_copy_tail(castNode(List, object), 1);
 
                if (!schema_does_not_exist_skipping(opcname, &msg, &name))
                {
                    msg = gettext_noop("operator class \"%s\" does not exist for access method \"%s\", skipping");
                    name = NameListToString(opcname);
                    args = strVal(linitial(castNode(List, object)));
                }
            }
            break;
        case OBJECT_OPFAMILY:
            {
                List       *opfname = list_copy_tail(castNode(List, object), 1);
 
                if (!schema_does_not_exist_skipping(opfname, &msg, &name))
                {
                    msg = gettext_noop("operator family \"%s\" does not exist for access method \"%s\", skipping");
                    name = NameListToString(opfname);
                    args = strVal(linitial(castNode(List, object)));
                }
            }
            break;
        case OBJECT_PUBLICATION:
            msg = gettext_noop("publication \"%s\" does not exist, skipping");
            name = strVal(object);
            break;
 
        case OBJECT_COLUMN:
        case OBJECT_DATABASE:
        case OBJECT_FOREIGN_TABLE:
        case OBJECT_INDEX:
        case OBJECT_MATVIEW:
        case OBJECT_ROLE:
        case OBJECT_SEQUENCE:
        case OBJECT_SUBSCRIPTION:
        case OBJECT_TABLE:
        case OBJECT_TABLESPACE:
        case OBJECT_VIEW:
 
            /*
             * These are handled elsewhere, so if someone gets here the code
             * is probably wrong or should be revisited.
             */
            elog(ERROR, "unsupported object type: %d", (int) objtype);
            break;
 
        case OBJECT_AMOP:
        case OBJECT_AMPROC:
        case OBJECT_ATTRIBUTE:
        case OBJECT_DEFAULT:
        case OBJECT_DEFACL:
        case OBJECT_DOMCONSTRAINT:
        case OBJECT_LARGEOBJECT:
        case OBJECT_PARAMETER_ACL:
        case OBJECT_PUBLICATION_NAMESPACE:
        case OBJECT_PUBLICATION_REL:
        case OBJECT_TABCONSTRAINT:
        case OBJECT_USER_MAPPING:
            /* These are currently not used or needed. */
            elog(ERROR, "unsupported object type: %d", (int) objtype);
            break;
 
            /* no default, to let compiler warn about missing case */
    }
    if (!msg)
        elog(ERROR, "unrecognized object type: %d", (int) objtype);
 
    if (!args)
        ereport(NOTICE, (errmsg(msg, name)));
    else
        ereport(NOTICE, (errmsg(msg, name, args)));
}