Generate pg_stat_get*() functions for tables using macros

The same code pattern is repeated 17 times for int64 counters (0 for
missing entry) and 5 times for timestamps (NULL for missing entry) on
table entries.  This code is switched to use a macro for the basic code
instead, shaving a few hundred lines of originally-duplicated code.  The
function names remain the same, but some fields of PgStat_StatTabEntry
have to be renamed to cope with the new style.

Author: Bertrand Drouvot
Reviewed-by: Nathan Bossart
Discussion: https:/postgr.es/m/20221204173207.GA2669116@nathanxps13

Author: michaelpq

src/backend/access/heap/README.HOT

@@ -271,7 +271,7 @@ physical tuple by eliminating an intermediate heap-only tuple or
 replacing a physical root tuple by a redirect pointer, a decrement in
 the table's number of dead tuples is reported to pgstats, which may
 postpone autovacuuming.  Note that we do not count replacing a root tuple
-by a DEAD line pointer as decrementing n_dead_tuples; we still want
+by a DEAD line pointer as decrementing dead_tuples; we still want
 autovacuum to run to clean up the index entries and DEAD item.
 
 This area probably needs further work ...

src/backend/postmaster/autovacuum.c

@@ -3081,9 +3081,9 @@ relation_needs_vacanalyze(Oid relid,
 	if (PointerIsValid(tabentry) && AutoVacuumingActive())
 	{
 		reltuples = classForm->reltuples;
-		vactuples = tabentry->n_dead_tuples;
-		instuples = tabentry->inserts_since_vacuum;
-		anltuples = tabentry->changes_since_analyze;
+		vactuples = tabentry->dead_tuples;
+		instuples = tabentry->ins_since_vacuum;
+		anltuples = tabentry->mod_since_analyze;
 
 		/* If the table hasn't yet been vacuumed, take reltuples as zero */
 		if (reltuples < 0)

src/backend/utils/activity/pgstat_relation.c

@@ -231,8 +231,8 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
 	shtabentry = (PgStatShared_Relation *) entry_ref->shared_stats;
 	tabentry = &shtabentry->stats;
 
-	tabentry->n_live_tuples = livetuples;
-	tabentry->n_dead_tuples = deadtuples;
+	tabentry->live_tuples = livetuples;
+	tabentry->dead_tuples = deadtuples;
 
 	/*
 	 * It is quite possible that a non-aggressive VACUUM ended up skipping
@@ -244,16 +244,16 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
 	 * autovacuum.  An anti-wraparound autovacuum will catch any persistent
 	 * stragglers.
 	 */
-	tabentry->inserts_since_vacuum = 0;
+	tabentry->ins_since_vacuum = 0;
 
 	if (IsAutoVacuumWorkerProcess())
 	{
-		tabentry->autovac_vacuum_timestamp = ts;
-		tabentry->autovac_vacuum_count++;
+		tabentry->last_autovacuum_time = ts;
+		tabentry->autovacuum_count++;
 	}
 	else
 	{
-		tabentry->vacuum_timestamp = ts;
+		tabentry->last_vacuum_time = ts;
 		tabentry->vacuum_count++;
 	}
 
@@ -264,7 +264,7 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
  * Report that the table was just analyzed.
  *
  * Caller must provide new live- and dead-tuples estimates, as well as a
- * flag indicating whether to reset the changes_since_analyze counter.
+ * flag indicating whether to reset the mod_since_analyze counter.
  */
 void
 pgstat_report_analyze(Relation rel,
@@ -318,25 +318,25 @@ pgstat_report_analyze(Relation rel,
 	shtabentry = (PgStatShared_Relation *) entry_ref->shared_stats;
 	tabentry = &shtabentry->stats;
 
-	tabentry->n_live_tuples = livetuples;
-	tabentry->n_dead_tuples = deadtuples;
+	tabentry->live_tuples = livetuples;
+	tabentry->dead_tuples = deadtuples;
 
 	/*
-	 * If commanded, reset changes_since_analyze to zero.  This forgets any
+	 * If commanded, reset mod_since_analyze to zero.  This forgets any
 	 * changes that were committed while the ANALYZE was in progress, but we
 	 * have no good way to estimate how many of those there were.
 	 */
 	if (resetcounter)
-		tabentry->changes_since_analyze = 0;
+		tabentry->mod_since_analyze = 0;
 
 	if (IsAutoVacuumWorkerProcess())
 	{
-		tabentry->autovac_analyze_timestamp = GetCurrentTimestamp();
-		tabentry->autovac_analyze_count++;
+		tabentry->last_autoanalyze_time = GetCurrentTimestamp();
+		tabentry->autoanalyze_count++;
 	}
 	else
 	{
-		tabentry->analyze_timestamp = GetCurrentTimestamp();
+		tabentry->last_analyze_time = GetCurrentTimestamp();
 		tabentry->analyze_count++;
 	}
 
@@ -798,22 +798,22 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
 	 */
 	if (lstats->t_counts.t_truncdropped)
 	{
-		tabentry->n_live_tuples = 0;
-		tabentry->n_dead_tuples = 0;
-		tabentry->inserts_since_vacuum = 0;
+		tabentry->live_tuples = 0;
+		tabentry->dead_tuples = 0;
+		tabentry->ins_since_vacuum = 0;
 	}
 
-	tabentry->n_live_tuples += lstats->t_counts.t_delta_live_tuples;
-	tabentry->n_dead_tuples += lstats->t_counts.t_delta_dead_tuples;
-	tabentry->changes_since_analyze += lstats->t_counts.t_changed_tuples;
-	tabentry->inserts_since_vacuum += lstats->t_counts.t_tuples_inserted;
+	tabentry->live_tuples += lstats->t_counts.t_delta_live_tuples;
+	tabentry->dead_tuples += lstats->t_counts.t_delta_dead_tuples;
+	tabentry->mod_since_analyze += lstats->t_counts.t_changed_tuples;
+	tabentry->ins_since_vacuum += lstats->t_counts.t_tuples_inserted;
 	tabentry->blocks_fetched += lstats->t_counts.t_blocks_fetched;
 	tabentry->blocks_hit += lstats->t_counts.t_blocks_hit;
 
-	/* Clamp n_live_tuples in case of negative delta_live_tuples */
-	tabentry->n_live_tuples = Max(tabentry->n_live_tuples, 0);
-	/* Likewise for n_dead_tuples */
-	tabentry->n_dead_tuples = Max(tabentry->n_dead_tuples, 0);
+	/* Clamp live_tuples in case of negative delta_live_tuples */
+	tabentry->live_tuples = Max(tabentry->live_tuples, 0);
+	/* Likewise for dead_tuples */
+	tabentry->dead_tuples = Max(tabentry->dead_tuples, 0);
 
 	pgstat_unlock_entry(entry_ref);