Re: pgstat: Flush some statistics within running transactions, take 2

> /* 24 | 8 */ PgStat_Counter tuples_hot_updated;
> /* 32 | 8 */ PgStat_Counter tuples_newpage_updated;
> /* 40 | 1 */ _Bool truncdropped;
> /* XXX 7-byte hole */
> /* 48 | 8 */ PgStat_Counter delta_live_tuples;
> /* 56 | 8 */ PgStat_Counter delta_dead_tuples;
> /* 64 | 8 */ PgStat_Counter changed_tuples;

right, These counters should be confined to PgStat_Counter fields,
and we can similar to what was done in 3cd3a039da7 to ensure
that the struct has no padding, using StaticAssertDecl().

truncdropped should be moved under PgStat_RelationStatus
directly, since it's not a counter anyhow.

I still think this is a much better way to organize the data and retain the
capability to do memcmp() rather than field-by-field comparisons.

WDYT?

--
Sami