Re: Online checksums verification in the backend - Mailing list pgsql-hackers

From Julien Rouhaud
Subject Re: Online checksums verification in the backend
Date
Msg-id 20200316084239.4hc35bjmevzztcct@nol
Whole thread Raw
In response to Re: Online checksums verification in the backend  (Masahiko Sawada <masahiko.sawada@2ndquadrant.com>)
Responses Re: Online checksums verification in the backend
List pgsql-hackers
On Mon, Mar 16, 2020 at 01:53:35PM +0900, Masahiko Sawada wrote:
>
> In addition to comments from Michael-san, here are my comments:
>
> 1.
> +   if (!is_member_of_role(GetUserId(), DEFAULT_ROLE_READ_SERVER_FILES))
> +       ereport(ERROR,
> +               (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
> +                errmsg("only superuser or a member of the
> pg_read_server_files role may use this function")));


Good point!  I'll fix it.


> +
> +   if (!DataChecksumsEnabled())
> +       elog(ERROR, "Data checksums are not enabled");
>
> I think it's better to reverse the order of the above checks.


Indeed.


>
> 2.
> +#define CRF_COLS           5   /* Number of output arguments in the SRF */
>
> Should it be SRF_COLS?


Oops, will fix.


>
> 3.
> +static void
> +check_delay_point(void)
> +{
> +   /* Always check for interrupts */
> +   CHECK_FOR_INTERRUPTS();
> +
> +   /* Nap if appropriate */
> +   if (!InterruptPending && VacuumCostBalance >= VacuumCostLimit)
> +   {
> +       int         msec;
> +
> +       msec = VacuumCostDelay * VacuumCostBalance / VacuumCostLimit;
> +       if (msec > VacuumCostDelay * 4)
> +           msec = VacuumCostDelay * 4;
> +
> +       pg_usleep(msec * 1000L);
> +
> +       VacuumCostBalance = 0;
> +
> +       /* Might have gotten an interrupt while sleeping */
> +       CHECK_FOR_INTERRUPTS();
> +   }
> +}
>
> Even if we use vacuum delay for this function, I think we need to set
> VacuumDelayActive and return if it's false, or it's better to just
> return if VacuumCostDelay == 0.


Good point, I'll fix that.


>
> 4.
> +static void
> +check_all_relations(TupleDesc tupdesc, Tuplestorestate *tupstore,
> +                         ForkNumber forknum)
>
> I also agree with Michael-san to remove this function. Instead we can
> check all relations by:
>
> select pg_check_relation(oid) from pg_class;


Sure, but ideally we should do that in a client program (eg.  pg_checksums)
that wouldn't maintain a transaction active for the whole execution.


> 6.
> Other typos
>
> s/dirted/dirtied/
> s/explictly/explicitly/


Will fix, thanks!



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