]> git.ipfire.org Git - thirdparty/postgresql.git/commitdiff
Prevent drop of tablespaces used by partitioned relations
authorAlvaro Herrera <alvherre@alvh.no-ip.org>
Thu, 14 Jan 2021 18:32:14 +0000 (15:32 -0300)
committerAlvaro Herrera <alvherre@alvh.no-ip.org>
Thu, 14 Jan 2021 18:32:14 +0000 (15:32 -0300)
When a tablespace is used in a partitioned relation (per commits
ca4103025dfe in pg12 for tables and 33e6c34c3267 in pg11 for indexes),
it is possible to drop the tablespace, potentially causing various
problems.  One such was reported in bug #16577, where a rewriting ALTER
TABLE causes a server crash.

Protect against this by using pg_shdepend to keep track of tablespaces
when used for relations that don't keep physical files; we now abort a
tablespace if we see that the tablespace is referenced from any
partitioned relations.

Backpatch this to 11, where this problem has been latent all along.  We
don't try to create pg_shdepend entries for existing partitioned
indexes/tables, but any ones that are modified going forward will be
protected.

Note slight behavior change: when trying to drop a tablespace that
contains both regular tables as well as partitioned ones, you'd
previously get ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE and now you'll
get ERRCODE_DEPENDENT_OBJECTS_STILL_EXIST.  Arguably, the latter is more
correct.

It is possible to add protecting pg_shdepend entries for existing
tables/indexes, by doing
  ALTER TABLE ONLY some_partitioned_table SET TABLESPACE pg_default;
  ALTER TABLE ONLY some_partitioned_table SET TABLESPACE original_tablespace;
for each partitioned table/index that is not in the database default
tablespace.  Because these partitioned objects do not have storage, no
file needs to be actually moved, so it shouldn't take more time than
what's required to acquire locks.

This query can be used to search for such relations:
SELECT ... FROM pg_class WHERE relkind IN ('p', 'I') AND reltablespace <> 0

Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/16577-881633a9f9894fd5@postgresql.org
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
doc/src/sgml/catalogs.sgml
src/backend/catalog/heap.c
src/backend/catalog/pg_shdepend.c
src/backend/commands/tablecmds.c
src/backend/commands/tablespace.c
src/include/catalog/dependency.h
src/test/regress/input/tablespace.source
src/test/regress/output/tablespace.source

index 75622250737cddd6651ccb58b7d48b63864588e1..9d6d65acd9f9779b64100c913e8cb6e7c75d7361 100644 (file)
@@ -6166,10 +6166,21 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       </para>
      </listitem>
     </varlistentry>
+
+    <varlistentry>
+     <term><symbol>SHARED_DEPENDENCY_TABLESPACE</symbol> (<literal>t</literal>)</term>
+     <listitem>
+      <para>
+       The referenced object (which must be a tablespace) is mentioned as
+       the tablespace for a relation that doesn't have storage.
+      </para>
+     </listitem>
+    </varlistentry>
    </variablelist>
 
    Other dependency flavors might be needed in future.  Note in particular
-   that the current definition only supports roles as referenced objects.
+   that the current definition only supports roles and tablespaces as referenced
+   objects.
   </para>
 
  </sect1>
index 8ebfe479ebe6a91db896055ad49b1d90ffc3986c..3c332e307dc761e18a9b1f4da5b0221a75cf19de 100644 (file)
@@ -376,6 +376,15 @@ heap_create(const char *relname,
                RelationCreateStorage(rel->rd_node, relpersistence);
        }
 
+       /*
+        * If a tablespace is specified, removal of that tablespace is normally
+        * protected by the existence of a physical file; but for relations with
+        * no files, add a pg_shdepend entry to account for that.
+        */
+       if (!create_storage && reltablespace != InvalidOid)
+               recordDependencyOnTablespace(RelationRelationId, relid,
+                                                                        reltablespace);
+
        return rel;
 }
 
index ca705190efc3fb789882e075858ab895eec706e7..a24e2cefa06d98d4de31a01d1140ed8e906046ae 100644 (file)
@@ -59,6 +59,7 @@
 #include "commands/schemacmds.h"
 #include "commands/subscriptioncmds.h"
 #include "commands/tablecmds.h"
+#include "commands/tablespace.h"
 #include "commands/typecmds.h"
 #include "storage/lmgr.h"
 #include "miscadmin.h"
@@ -181,11 +182,14 @@ recordDependencyOnOwner(Oid classId, Oid objectId, Oid owner)
  *
  * There must be no more than one existing entry for the given dependent
  * object and dependency type! So in practice this can only be used for
- * updating SHARED_DEPENDENCY_OWNER entries, which should have that property.
+ * updating SHARED_DEPENDENCY_OWNER and SHARED_DEPENDENCY_TABLESPACE
+ * entries, which should have that property.
  *
  * If there is no previous entry, we assume it was referencing a PINned
  * object, so we create a new entry.  If the new referenced object is
  * PINned, we don't create an entry (and drop the old one, if any).
+ * (For tablespaces, we don't record dependencies in certain cases, so
+ * there are other possible reasons for entries to be missing.)
  *
  * sdepRel must be the pg_shdepend relation, already opened and suitably
  * locked.
@@ -339,6 +343,58 @@ changeDependencyOnOwner(Oid classId, Oid objectId, Oid newOwnerId)
        heap_close(sdepRel, RowExclusiveLock);
 }
 
+/*
+ * recordDependencyOnTablespace
+ *
+ * A convenient wrapper of recordSharedDependencyOn -- register the specified
+ * tablespace as default for the given object.
+ *
+ * Note: it's the caller's responsibility to ensure that there isn't a
+ * tablespace entry for the object already.
+ */
+void
+recordDependencyOnTablespace(Oid classId, Oid objectId, Oid tablespace)
+{
+       ObjectAddress myself,
+                                 referenced;
+
+       ObjectAddressSet(myself, classId, objectId);
+       ObjectAddressSet(referenced, TableSpaceRelationId, tablespace);
+
+       recordSharedDependencyOn(&myself, &referenced,
+                                                        SHARED_DEPENDENCY_TABLESPACE);
+}
+
+/*
+ * changeDependencyOnTablespace
+ *
+ * Update the shared dependencies to account for the new tablespace.
+ *
+ * Note: we don't need an objsubid argument because only whole objects
+ * have tablespaces.
+ */
+void
+changeDependencyOnTablespace(Oid classId, Oid objectId, Oid newTablespaceId)
+{
+       Relation        sdepRel;
+
+       sdepRel = heap_open(SharedDependRelationId, RowExclusiveLock);
+
+       if (newTablespaceId != DEFAULTTABLESPACE_OID &&
+               newTablespaceId != InvalidOid)
+               shdepChangeDep(sdepRel,
+                                          classId, objectId, 0,
+                                          TableSpaceRelationId, newTablespaceId,
+                                          SHARED_DEPENDENCY_TABLESPACE);
+       else
+               shdepDropDependency(sdepRel,
+                                                       classId, objectId, 0, true,
+                                                       InvalidOid, InvalidOid,
+                                                       SHARED_DEPENDENCY_INVALID);
+
+       heap_close(sdepRel, RowExclusiveLock);
+}
+
 /*
  * getOidListDiff
  *             Helper for updateAclDependencies.
@@ -999,13 +1055,6 @@ shdepLockAndCheckObject(Oid classId, Oid objectId)
                                                                objectId)));
                        break;
 
-                       /*
-                        * Currently, this routine need not support any other shared
-                        * object types besides roles.  If we wanted to record explicit
-                        * dependencies on databases or tablespaces, we'd need code along
-                        * these lines:
-                        */
-#ifdef NOT_USED
                case TableSpaceRelationId:
                        {
                                /* For lack of a syscache on pg_tablespace, do this: */
@@ -1019,7 +1068,6 @@ shdepLockAndCheckObject(Oid classId, Oid objectId)
                                pfree(tablespace);
                                break;
                        }
-#endif
 
                case DatabaseRelationId:
                        {
@@ -1079,6 +1127,8 @@ storeObjectDescription(StringInfo descs,
                                appendStringInfo(descs, _("privileges for %s"), objdesc);
                        else if (deptype == SHARED_DEPENDENCY_POLICY)
                                appendStringInfo(descs, _("target of %s"), objdesc);
+                       else if (deptype == SHARED_DEPENDENCY_TABLESPACE)
+                               appendStringInfo(descs, _("tablespace for %s"), objdesc);
                        else
                                elog(ERROR, "unrecognized dependency type: %d",
                                         (int) deptype);
index 18dcb65f9f1e8e573e048b577355d256fdbc9848..a149ca044c1935b51414741de93b20e92eb07c49 100644 (file)
@@ -11845,6 +11845,10 @@ ATExecPartedIdxSetTableSpace(Relation rel, Oid newTableSpace)
        rd_rel->reltablespace = (newTableSpace == MyDatabaseTableSpace) ? InvalidOid : newTableSpace;
        CatalogTupleUpdate(pg_class, &tuple->t_self, tuple);
 
+       /* Record dependency on tablespace */
+       changeDependencyOnTablespace(RelationRelationId,
+                                                                indexOid, rd_rel->reltablespace);
+
        InvokeObjectPostAlterHook(RelationRelationId, indexOid, 0);
 
        heap_freetuple(tuple);
index e4cd961e3ba7bf6f7f46938f4722e261ddc392e8..da01c7b307542f78c92972c89934701588f28a46 100644 (file)
@@ -408,6 +408,8 @@ DropTableSpace(DropTableSpaceStmt *stmt)
        HeapTuple       tuple;
        ScanKeyData entry[1];
        Oid                     tablespaceoid;
+       char       *detail;
+       char       *detail_log;
 
        /*
         * Find the target tuple
@@ -455,6 +457,16 @@ DropTableSpace(DropTableSpaceStmt *stmt)
                aclcheck_error(ACLCHECK_NO_PRIV, OBJECT_TABLESPACE,
                                           tablespacename);
 
+       /* Check for pg_shdepend entries depending on this tablespace */
+       if (checkSharedDependencies(TableSpaceRelationId, tablespaceoid,
+                                                               &detail, &detail_log))
+               ereport(ERROR,
+                               (errcode(ERRCODE_DEPENDENT_OBJECTS_STILL_EXIST),
+                                errmsg("tablespace \"%s\" cannot be dropped because some objects depend on it",
+                                               tablespacename),
+                                errdetail_internal("%s", detail),
+                                errdetail_log("%s", detail_log)));
+
        /* DROP hook for the tablespace being removed */
        InvokeObjectDropHook(TableSpaceRelationId, tablespaceoid, 0);
 
index ec79e2c7dc2cc25405584c0ed525549c389db7a3..74d4686bb7dc7e0d828c974b79a7c217126e44d1 100644 (file)
@@ -122,6 +122,12 @@ typedef enum DependencyType
  * a role mentioned in a policy object.  The referenced object must be a
  * pg_authid entry.
  *
+ * (e) a SHARED_DEPENDENCY_TABLESPACE entry means that the referenced
+ * object is a tablespace mentioned in a relation without storage.  The
+ * referenced object must be a pg_tablespace entry.  (Relations that have
+ * storage don't need this: they are protected by the existence of a physical
+ * file in the tablespace.)
+ *
  * SHARED_DEPENDENCY_INVALID is a value used as a parameter in internal
  * routines, and is not valid in the catalog itself.
  */
@@ -131,6 +137,7 @@ typedef enum SharedDependencyType
        SHARED_DEPENDENCY_OWNER = 'o',
        SHARED_DEPENDENCY_ACL = 'a',
        SHARED_DEPENDENCY_POLICY = 'r',
+       SHARED_DEPENDENCY_TABLESPACE = 't',
        SHARED_DEPENDENCY_INVALID = 0
 } SharedDependencyType;
 
@@ -280,6 +287,12 @@ extern void recordDependencyOnOwner(Oid classId, Oid objectId, Oid owner);
 extern void changeDependencyOnOwner(Oid classId, Oid objectId,
                                                Oid newOwnerId);
 
+extern void recordDependencyOnTablespace(Oid classId, Oid objectId,
+                                                                                Oid tablespace);
+
+extern void changeDependencyOnTablespace(Oid classId, Oid objectId,
+                                                                                Oid newTablespaceId);
+
 extern void updateAclDependencies(Oid classId, Oid objectId, int32 objectSubId,
                                          Oid ownerId,
                                          int noldmembers, Oid *oldmembers,
index 2ac757cfab247b7873acdf36328cb6fd9f085e0d..920f4e630f24d2e4421ffa759cc6c7a61c0f181e 100644 (file)
@@ -115,6 +115,9 @@ CREATE TABLESPACE regress_badspace LOCATION '/no/such/location';
 -- No such tablespace
 CREATE TABLE bar (i int) TABLESPACE regress_nosuchspace;
 
+-- Fail, in use for some partitioned object
+DROP TABLESPACE regress_tblspace;
+ALTER INDEX testschema.part_a_idx SET TABLESPACE pg_default;
 -- Fail, not empty
 DROP TABLESPACE regress_tblspace;
 
index 2e78e5ece689155526105a72b070374fe0b4f01f..8a2bdc87fc98aac87dc49c2fbe723cb48bf18c68 100644 (file)
@@ -234,6 +234,11 @@ ERROR:  directory "/no/such/location" does not exist
 -- No such tablespace
 CREATE TABLE bar (i int) TABLESPACE regress_nosuchspace;
 ERROR:  tablespace "regress_nosuchspace" does not exist
+-- Fail, in use for some partitioned object
+DROP TABLESPACE regress_tblspace;
+ERROR:  tablespace "regress_tblspace" cannot be dropped because some objects depend on it
+DETAIL:  tablespace for index testschema.part_a_idx
+ALTER INDEX testschema.part_a_idx SET TABLESPACE pg_default;
 -- Fail, not empty
 DROP TABLESPACE regress_tblspace;
 ERROR:  tablespace "regress_tblspace" is not empty