assert pg_class.relnatts is consistent

Forking this thread for two tangential patches which I think are more
worthwhile than the original topic's patch.
https://www.postgresql.org/message-id/20200207143935.GP403%40telsasoft.com

Is there a better place to implement assertion from 0002 ?

On Fri, Feb 07, 2020 at 08:39:35AM -0600, Justin Pryzby wrote:
> From 7eea0a17e495fe13379ffd589b551f2f145f5672 Mon Sep 17 00:00:00 2001
> From: Justin Pryzby <pryzbyj@telsasoft.com>
> Date: Thu, 6 Feb 2020 21:48:13 -0600
> Subject: [PATCH v1 1/3] Update comment obsolete since b9b8831a
> 
> ---
>  src/backend/commands/cluster.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
> index e9d7a7f..3adcbeb 100644
> --- a/src/backend/commands/cluster.c
> +++ b/src/backend/commands/cluster.c
> @@ -1539,9 +1539,9 @@ get_tables_to_cluster(MemoryContext cluster_context)
>  
>      /*
>       * Get all indexes that have indisclustered set and are owned by
> -     * appropriate user. System relations or nailed-in relations cannot ever
> -     * have indisclustered set, because CLUSTER will refuse to set it when
> -     * called with one of them as argument.
> +     * appropriate user. Shared relations cannot ever have indisclustered
> +     * set, because CLUSTER will refuse to set it when called with one as
> +     * an argument.
>       */
>      indRelation = table_open(IndexRelationId, AccessShareLock);
>      ScanKeyInit(&entry,
> -- 
> 2.7.4
> 

> From 4777be522a7aa8b8c77b13f765cbd02043438f2a Mon Sep 17 00:00:00 2001
> From: Justin Pryzby <pryzbyj@telsasoft.com>
> Date: Fri, 7 Feb 2020 08:12:50 -0600
> Subject: [PATCH v1 2/3] Give developer a helpful kick in the pants if they
>  change natts in one place but not another
> 
> ---
>  src/backend/bootstrap/bootstrap.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
> index bfc629c..d5e1888 100644
> --- a/src/backend/bootstrap/bootstrap.c
> +++ b/src/backend/bootstrap/bootstrap.c
> @@ -25,7 +25,9 @@
>  #include "access/xlog_internal.h"
>  #include "bootstrap/bootstrap.h"
>  #include "catalog/index.h"
> +#include "catalog/pg_class.h"
>  #include "catalog/pg_collation.h"
> +#include "catalog/pg_proc.h"
>  #include "catalog/pg_type.h"
>  #include "common/link-canary.h"
>  #include "libpq/pqsignal.h"
> @@ -49,6 +51,7 @@
>  #include "utils/ps_status.h"
>  #include "utils/rel.h"
>  #include "utils/relmapper.h"
> +#include "utils/syscache.h"
>  
>  uint32        bootstrap_data_checksum_version = 0;    /* No checksum */
>  
> @@ -602,6 +605,26 @@ boot_openrel(char *relname)
>      TableScanDesc scan;
>      HeapTuple    tup;
>  
> +    /* Check that pg_class data is consistent now, rather than failing obscurely later */
> +    struct { Oid oid; int natts; }
> +        checknatts[] = {
> +        {RelationRelationId, Natts_pg_class,},
> +        {TypeRelationId, Natts_pg_type,},
> +        {AttributeRelationId, Natts_pg_attribute,},
> +        {ProcedureRelationId, Natts_pg_proc,},
> +    };
> +
> +    for (int i=0; i<lengthof(checknatts); ++i) {
> +        Form_pg_class    classForm;
> +        HeapTuple    tuple;
> +        tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(checknatts[i].oid));
> +        if (!HeapTupleIsValid(tuple))
> +            elog(ERROR, "cache lookup failed for relation %u", checknatts[i].oid);
> +        classForm = (Form_pg_class) GETSTRUCT(tuple);
> +        Assert(checknatts[i].natts == classForm->relnatts);
> +        ReleaseSysCache(tuple);
> +    }
> +
>      if (strlen(relname) >= NAMEDATALEN)
>          relname[NAMEDATALEN - 1] = '\0';
>  
> -- 
> 2.7.4
>