Re: [HACKERS] [PATCH] Lockable views

From: Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp>
To: andres(at)anarazel(dot)de
Cc: nagata(at)sraoss(dot)co(dot)jp, ishii(at)sraoss(dot)co(dot)jp, robertmhaas(at)gmail(dot)com, thomas(dot)munro(at)enterprisedb(dot)com, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [HACKERS] [PATCH] Lockable views
Date: 2018-03-30 00:48:02
Message-ID: 20180330.094802.1218289934398032890.t-ishii@sraoss.co.jp
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Andres,

I have just pushed the v10 patch. Yugo will reply back to your point
but I will look into your review as well.

Thanks.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> 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.
>
> 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.
>
>
>> @@ -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.
>
>
>> /*
>> + * 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?
>
> Greetings,
>
> Andres Freund

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