On Thu, 29 Mar 2018 17:26:36 -0700
Andres Freund <[email protected]> wrote:
Thank you for your comments. I attach a patch to fix issues
you've pointed out.
> Hi,
>
> On 2018-03-28 20:26:48 +0900, Yugo Nagata wrote:
> > diff --git a/doc/src/sgml/ref/lock.sgml b/doc/src/sgml/ref/lock.sgml
> > index b2c7203..96d477c 100644
> > --- a/doc/src/sgml/ref/lock.sgml
> > +++ b/doc/src/sgml/ref/lock.sgml
> > @@ -46,6 +46,11 @@ LOCK [ TABLE ] [ ONLY ] <replaceable
> > class="parameter">name</replaceable> [ * ]
> > </para>
> >
> > <para>
> > + When a view is specified to be locked, all relations appearing in the
> > view
> > + definition query are also locked recursively with the same lock mode.
> > + </para>
>
> Trailing space added. I'd remove "specified to be" from the sentence.
Fixed.
>
> I think mentioning how this interacts with permissions would be a good
> idea too. Given how operations use the view's owner to recurse, that's
> not obvious. Should also explain what permissions are required to do the
> operation on the view.
Added a description about permissions into the documentation.
>
>
> > @@ -86,15 +92,17 @@ RangeVarCallbackForLockTable(const RangeVar *rv, Oid
> > relid, Oid oldrelid,
> > return; /* woops, concurrently
> > dropped; no permissions
> > * check */
> >
> > - /* Currently, we only allow plain tables to be locked */
> > - if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE)
> > +
>
> This newline looks spurious to me.
Removed.
>
>
> > /*
> > + * Apply LOCK TABLE recursively over a view
> > + *
> > + * All tables and views appearing in the view definition query are locked
> > + * recursively with the same lock mode.
> > + */
> > +
> > +typedef struct
> > +{
> > + Oid root_reloid;
> > + LOCKMODE lockmode;
> > + bool nowait;
> > + Oid viewowner;
> > + Oid viewoid;
> > +} LockViewRecurse_context;
>
> Probably wouldn't hurt to pgindent the larger changes in the patch.
>
>
> > +static bool
> > +LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
> > +{
> > + if (node == NULL)
> > + return false;
> > +
> > + if (IsA(node, Query))
> > + {
> > + Query *query = (Query *) node;
> > + ListCell *rtable;
> > +
> > + foreach(rtable, query->rtable)
> > + {
> > + RangeTblEntry *rte = lfirst(rtable);
> > + AclResult aclresult;
> > +
> > + Oid relid = rte->relid;
> > + char relkind = rte->relkind;
> > + char *relname = get_rel_name(relid);
> > +
> > + /* The OLD and NEW placeholder entries in the view's
> > rtable are skipped. */
> > + if (relid == context->viewoid &&
> > + (!strcmp(rte->eref->aliasname, "old") ||
> > !strcmp(rte->eref->aliasname, "new")))
> > + continue;
> > +
> > + /* Currently, we only allow plain tables or views to be
> > locked. */
> > + if (relkind != RELKIND_RELATION && relkind !=
> > RELKIND_PARTITIONED_TABLE &&
> > + relkind != RELKIND_VIEW)
> > + continue;
> > +
> > + /* Check infinite recursion in the view definition. */
> > + if (relid == context->root_reloid)
> > + ereport(ERROR,
> > +
> > (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
> > + errmsg("infinite recursion
> > detected in rules for relation \"%s\"",
> > +
> > get_rel_name(context->root_reloid))));
>
> Hm, how can that happen? And if it can happen, why can it only happen
> with the root relation?
For example, the following queries cause the infinite recursion of views.
This is detected and the error is raised.
create table t (i int);
create view v1 as select 1;
create view v2 as select * from v1;
create or replace view v1 as select * from v2;
begin;
lock v1;
abort;
However, I found that the previous patch could not handle the following
situation in which the root relation itself doesn't have infinite recursion.
create view v3 as select * from v1;
begin;
lock v3;
abort;
This fixed in the attached patch.
Regards,
>
> Greetings,
>
> Andres Freund
--
Yugo Nagata <[email protected]>
diff --git a/doc/src/sgml/ref/lock.sgml b/doc/src/sgml/ref/lock.sgml
index 96d477c..12303fe 100644
--- a/doc/src/sgml/ref/lock.sgml
+++ b/doc/src/sgml/ref/lock.sgml
@@ -46,8 +46,8 @@ LOCK [ TABLE ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ * ]
</para>
<para>
- When a view is specified to be locked, all relations appearing in the view
- definition query are also locked recursively with the same lock mode.
+ When a view is locked, all relations appearing in the view definition
+ query are also locked recursively with the same lock mode.
</para>
<para>
@@ -174,6 +174,13 @@ LOCK [ TABLE ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ * ]
</para>
<para>
+ The user performint the lock on the view must have the corresponding privilege
+ on the view. In addition the view's owner must have the relevant privileges on
+ the underlying base relations, but the user performing the lock does
+ not need any permissions on the underlying base relations.
+ </para>
+
+ <para>
<command>LOCK TABLE</command> is useless outside a transaction block: the lock
would remain held only to the completion of the statement. Therefore
<productname>PostgreSQL</productname> reports an error if <command>LOCK</command>
diff --git a/src/backend/commands/lockcmds.c b/src/backend/commands/lockcmds.c
index b247c0f..c46dc36 100644
--- a/src/backend/commands/lockcmds.c
+++ b/src/backend/commands/lockcmds.c
@@ -31,7 +31,7 @@ static void LockTableRecurse(Oid reloid, LOCKMODE lockmode, bool nowait, Oid use
static AclResult LockTableAclCheck(Oid relid, LOCKMODE lockmode, Oid userid);
static void RangeVarCallbackForLockTable(const RangeVar *rv, Oid relid,
Oid oldrelid, void *arg);
-static void LockViewRecurse(Oid reloid, Oid root_reloid, LOCKMODE lockmode, bool nowait);
+static void LockViewRecurse(Oid reloid, LOCKMODE lockmode, bool nowait, List *ancestor_views);
/*
* LOCK TABLE
@@ -67,7 +67,7 @@ LockTableCommand(LockStmt *lockstmt)
(void *) &lockstmt->mode);
if (get_rel_relkind(reloid) == RELKIND_VIEW)
- LockViewRecurse(reloid, reloid, lockstmt->mode, lockstmt->nowait);
+ LockViewRecurse(reloid, lockstmt->mode, lockstmt->nowait, NIL);
else if (recurse)
LockTableRecurse(reloid, lockstmt->mode, lockstmt->nowait, GetUserId());
}
@@ -92,7 +92,6 @@ RangeVarCallbackForLockTable(const RangeVar *rv, Oid relid, Oid oldrelid,
return; /* woops, concurrently dropped; no permissions
* check */
-
/* Currently, we only allow plain tables or views to be locked */
if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE &&
relkind != RELKIND_VIEW)
@@ -178,11 +177,11 @@ LockTableRecurse(Oid reloid, LOCKMODE lockmode, bool nowait, Oid userid)
typedef struct
{
- Oid root_reloid;
LOCKMODE lockmode;
bool nowait;
Oid viewowner;
Oid viewoid;
+ List *ancestor_views;
} LockViewRecurse_context;
static bool
@@ -216,11 +215,11 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
continue;
/* Check infinite recursion in the view definition. */
- if (relid == context->root_reloid)
+ if (list_member_oid(context->ancestor_views, relid))
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("infinite recursion detected in rules for relation \"%s\"",
- get_rel_name(context->root_reloid))));
+ get_rel_name(relid))));
/* Check permissions with the view owner's privilege. */
aclresult = LockTableAclCheck(relid, context->lockmode, context->viewowner);
@@ -237,7 +236,7 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
relname)));
if (relkind == RELKIND_VIEW)
- LockViewRecurse(relid, context->root_reloid, context->lockmode, context->nowait);
+ LockViewRecurse(relid, context->lockmode, context->nowait, context->ancestor_views);
else if (rte->inh)
LockTableRecurse(relid, context->lockmode, context->nowait, context->viewowner);
}
@@ -254,7 +253,7 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
}
static void
-LockViewRecurse(Oid reloid, Oid root_reloid, LOCKMODE lockmode, bool nowait)
+LockViewRecurse(Oid reloid, LOCKMODE lockmode, bool nowait, List *ancestor_views)
{
LockViewRecurse_context context;
@@ -264,14 +263,17 @@ LockViewRecurse(Oid reloid, Oid root_reloid, LOCKMODE lockmode, bool nowait)
view = heap_open(reloid, NoLock);
viewquery = get_view_query(view);
- context.root_reloid = root_reloid;
context.lockmode = lockmode;
context.nowait = nowait;
context.viewowner = view->rd_rel->relowner;
context.viewoid = reloid;
+ context.ancestor_views = lcons_oid(reloid, ancestor_views);
LockViewRecurse_walker((Node *) viewquery, &context);
+ ancestor_views = list_delete_oid(ancestor_views, reloid);
+
+
heap_close(view, NoLock);
}
