Add context type field to pg_backend_memory_contexts

Since we now (as of v17) have 4 MemoryContext types, the type of context
seems like useful information to include in the pg_backend_memory_contexts
view.  Here we add that.

Reviewed-by: David Christensen, Michael Paquier
Discussion: https://postgr.es/m/CAApHDvrXX1OR09Zjb5TnB0AwCKze9exZN%3D9Nxxg1ZCVV8W-3BA%40mail.gmail.com

doc/src/sgml/system-views.sgml

@@ -490,6 +490,15 @@
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>type</structfield> <type>text</type>
+      </para>
+      <para>
+       Type of the memory context
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
        <structfield>level</structfield> <type>int4</type>

src/backend/utils/adt/mcxtfuncs.c

@@ -36,7 +36,7 @@ PutMemoryContextsStatsTupleStore(Tuplestorestate *tupstore,
 								 TupleDesc tupdesc, MemoryContext context,
 								 const char *parent, int level)
 {
-#define PG_GET_BACKEND_MEMORY_CONTEXTS_COLS	9
+#define PG_GET_BACKEND_MEMORY_CONTEXTS_COLS	10
 
 	Datum		values[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
 	bool		nulls[PG_GET_BACKEND_MEMORY_CONTEXTS_COLS];
@@ -44,6 +44,7 @@ PutMemoryContextsStatsTupleStore(Tuplestorestate *tupstore,
 	MemoryContext child;
 	const char *name;
 	const char *ident;
+	const char *type;
 
 	Assert(MemoryContextIsValid(context));
 
@@ -96,12 +97,32 @@ PutMemoryContextsStatsTupleStore(Tuplestorestate *tupstore,
 	else
 		nulls[2] = true;
 
-	values[3] = Int32GetDatum(level);
-	values[4] = Int64GetDatum(stat.totalspace);
-	values[5] = Int64GetDatum(stat.nblocks);
-	values[6] = Int64GetDatum(stat.freespace);
-	values[7] = Int64GetDatum(stat.freechunks);
-	values[8] = Int64GetDatum(stat.totalspace - stat.freespace);
+	switch (context->type)
+	{
+		case T_AllocSetContext:
+			type = "AllocSet";
+			break;
+		case T_GenerationContext:
+			type = "Generation";
+			break;
+		case T_SlabContext:
+			type = "Slab";
+			break;
+		case T_BumpContext:
+			type = "Bump";
+			break;
+		default:
+			type = "???";
+			break;
+	}
+
+	values[3] = CStringGetTextDatum(type);
+	values[4] = Int32GetDatum(level);
+	values[5] = Int64GetDatum(stat.totalspace);
+	values[6] = Int64GetDatum(stat.nblocks);
+	values[7] = Int64GetDatum(stat.freespace);
+	values[8] = Int64GetDatum(stat.freechunks);
+	values[9] = Int64GetDatum(stat.totalspace - stat.freespace);
 	tuplestore_putvalues(tupstore, tupdesc, values, nulls);
 
 	for (child = context->firstchild; child != NULL; child = child->nextchild)

src/include/catalog/catversion.h

@@ -57,6 +57,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202406281
+#define CATALOG_VERSION_NO	202407011
 
 #endif

src/include/catalog/pg_proc.dat

@@ -8279,9 +8279,9 @@
   proname => 'pg_get_backend_memory_contexts', prorows => '100',
   proretset => 't', provolatile => 'v', proparallel => 'r',
   prorettype => 'record', proargtypes => '',
-  proallargtypes => '{text,text,text,int4,int8,int8,int8,int8,int8}',
-  proargmodes => '{o,o,o,o,o,o,o,o,o}',
-  proargnames => '{name, ident, parent, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes}',
+  proallargtypes => '{text,text,text,text,int4,int8,int8,int8,int8,int8}',
+  proargmodes => '{o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{name, ident, parent, type, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes}',
   prosrc => 'pg_get_backend_memory_contexts' },
 
 # logging memory contexts of the specified backend

src/test/regress/expected/rules.out

@@ -1306,13 +1306,14 @@ pg_available_extensions| SELECT e.name,
 pg_backend_memory_contexts| SELECT name,
     ident,
     parent,
+    type,
     level,
     total_bytes,
     total_nblocks,
     free_bytes,
     free_chunks,
     used_bytes
-   FROM pg_get_backend_memory_contexts() pg_get_backend_memory_contexts(name, ident, parent, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes);
+   FROM pg_get_backend_memory_contexts() pg_get_backend_memory_contexts(name, ident, parent, type, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes);
 pg_config| SELECT name,
     setting
    FROM pg_config() pg_config(name, setting);

src/test/regress/expected/sysviews.out

@@ -21,11 +21,11 @@ select count(*) >= 0 as ok from pg_available_extensions;
 
 -- The entire output of pg_backend_memory_contexts is not stable,
 -- we test only the existence and basic condition of TopMemoryContext.
-select name, ident, parent, level, total_bytes >= free_bytes
+select type, name, ident, parent, level, total_bytes >= free_bytes
   from pg_backend_memory_contexts where level = 0;
-       name       | ident | parent | level | ?column? 
-------------------+-------+--------+-------+----------
- TopMemoryContext |       |        |     0 | t
+   type   |       name       | ident | parent | level | ?column? 
+----------+------------------+-------+--------+-------+----------
+ AllocSet | TopMemoryContext |       |        |     0 | t
 (1 row)
 
 -- We can exercise some MemoryContext type stats functions.  Most of the
@@ -43,11 +43,11 @@ fetch 1 from cur;
  bbbbbbbbbb | 2
 (1 row)
 
-select name, parent, total_bytes > 0, total_nblocks, free_bytes > 0, free_chunks
+select type, name, parent, total_bytes > 0, total_nblocks, free_bytes > 0, free_chunks
 from pg_backend_memory_contexts where name = 'Caller tuples';
-     name      |     parent     | ?column? | total_nblocks | ?column? | free_chunks 
----------------+----------------+----------+---------------+----------+-------------
- Caller tuples | TupleSort sort | t        |             2 | t        |           0
+ type |     name      |     parent     | ?column? | total_nblocks | ?column? | free_chunks 
+------+---------------+----------------+----------+---------------+----------+-------------
+ Bump | Caller tuples | TupleSort sort | t        |             2 | t        |           0
 (1 row)
 
 rollback;

src/test/regress/sql/sysviews.sql

@@ -14,7 +14,7 @@ select count(*) >= 0 as ok from pg_available_extensions;
 
 -- The entire output of pg_backend_memory_contexts is not stable,
 -- we test only the existence and basic condition of TopMemoryContext.
-select name, ident, parent, level, total_bytes >= free_bytes
+select type, name, ident, parent, level, total_bytes >= free_bytes
   from pg_backend_memory_contexts where level = 0;
 
 -- We can exercise some MemoryContext type stats functions.  Most of the
@@ -28,7 +28,7 @@ declare cur cursor for select left(a,10), b
   from (values(repeat('a', 512 * 1024),1),(repeat('b', 512),2)) v(a,b)
   order by v.a desc;
 fetch 1 from cur;
-select name, parent, total_bytes > 0, total_nblocks, free_bytes > 0, free_chunks
+select type, name, parent, total_bytes > 0, total_nblocks, free_bytes > 0, free_chunks
 from pg_backend_memory_contexts where name = 'Caller tuples';
 rollback;