Fix typos and grammar in documentation and code comments

Comment fixes are applied on HEAD, and documentation improvements are
applied on back-branches where needed.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20210408164008.GJ6592@telsasoft.com
Backpatch-through: 9.6

src/backend/catalog/heap.c

@@ -1119,6 +1119,7 @@ AddNewRelationType(const char *typeName,
  *	reltypeid: OID to assign to rel's rowtype, or InvalidOid to select one
  *	reloftypeid: if a typed table, OID of underlying type; else InvalidOid
  *	ownerid: OID of new rel's owner
+ *	accessmtd: OID of new rel's access method
  *	tupdesc: tuple descriptor (source of column definitions)
  *	cooked_constraints: list of precooked check constraints and defaults
  *	relkind: relkind for new rel

src/backend/commands/analyze.c

@@ -617,7 +617,7 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 	 *
 	 * We assume that VACUUM hasn't set pg_class.reltuples already, even
 	 * during a VACUUM ANALYZE.  Although VACUUM often updates pg_class,
-	 * exceptions exists.  A "VACUUM (ANALYZE, INDEX_CLEANUP OFF)" command
+	 * exceptions exist.  A "VACUUM (ANALYZE, INDEX_CLEANUP OFF)" command
 	 * will never update pg_class entries for index relations.  It's also
 	 * possible that an individual index's pg_class entry won't be updated
 	 * during VACUUM if the index AM returns NULL from its amvacuumcleanup()

src/backend/commands/cluster.c

@@ -1422,7 +1422,7 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 								 PROGRESS_CLUSTER_PHASE_FINAL_CLEANUP);
 
 	/*
-	 * If the relation being rebuild is pg_class, swap_relation_files()
+	 * If the relation being rebuilt is pg_class, swap_relation_files()
 	 * couldn't update pg_class's own pg_class entry (check comments in
 	 * swap_relation_files()), thus relfrozenxid was not updated. That's
 	 * annoying because a potential reason for doing a VACUUM FULL is a

src/backend/commands/copyfrom.c

@@ -410,7 +410,7 @@ CopyMultiInsertBufferCleanup(CopyMultiInsertInfo *miinfo,
  * Once flushed we also trim the tracked buffers list down to size by removing
  * the buffers created earliest first.
  *
- * Callers should pass 'curr_rri' is the ResultRelInfo that's currently being
+ * Callers should pass 'curr_rri' as the ResultRelInfo that's currently being
  * used.  When cleaning up old buffers we'll never remove the one for
  * 'curr_rri'.
  */

src/backend/statistics/extended_stats.c

@@ -254,7 +254,7 @@ BuildRelationExtStatistics(Relation onerel, double totalrows,
  * that would require additional columns.
  *
  * See statext_compute_stattarget for details about how we compute statistics
- * target for a statistics objects (from the object target, attribute targets
+ * target for a statistics object (from the object target, attribute targets
  * and default statistics target).
  */
 int

src/backend/utils/adt/jsonfuncs.c

@@ -1651,7 +1651,7 @@ push_null_elements(JsonbParseState **ps, int num)
  * this path. E.g. the path [a][0][b] with the new value 1 will produce the
  * structure {a: [{b: 1}]}.
  *
- * Called is responsible to make sure such path does not exist yet.
+ * Caller is responsible to make sure such path does not exist yet.
  */
 static void
 push_path(JsonbParseState **st, int level, Datum *path_elems,
@@ -4887,7 +4887,7 @@ IteratorConcat(JsonbIterator **it1, JsonbIterator **it2,
  * than just one last element, this flag will instruct to create the whole
  * chain of corresponding objects and insert the value.
  *
- * JB_PATH_CONSISTENT_POSITION for an array indicates that the called wants to
+ * JB_PATH_CONSISTENT_POSITION for an array indicates that the caller wants to
  * keep values with fixed indices. Indices for existing elements could be
  * changed (shifted forward) in case if the array is prepended with a new value
  * and a negative index out of the range, so this behavior will be prevented

src/bin/pg_amcheck/t/004_verify_heapam.pl

@@ -175,7 +175,7 @@ sub write_tuple
 	seek($fh, $offset, 0)
 		or BAIL_OUT("seek failed: $!");
 	defined(syswrite($fh, $buffer, HEAPTUPLE_PACK_LENGTH))
-		or BAIL_OUT("syswrite failed: $!");;
+		or BAIL_OUT("syswrite failed: $!");
 	return;
 }
 

src/include/lib/sort_template.h

@@ -241,7 +241,7 @@ ST_SCOPE void ST_SORT(ST_ELEMENT_TYPE *first, size_t n
 
 /*
  * Find the median of three values.  Currently, performance seems to be best
- * if the the comparator is inlined here, but the med3 function is not inlined
+ * if the comparator is inlined here, but the med3 function is not inlined
  * in the qsort function.
  */
 static pg_noinline ST_ELEMENT_TYPE *

src/include/utils/guc.h

@@ -90,13 +90,12 @@ typedef enum
  * dividing line between "interactive" and "non-interactive" sources for
  * error reporting purposes.
  *
- * PGC_S_TEST is used when testing values to be used later ("doit" will always
- * be false, so this never gets stored as the actual source of any value).
- * For example, ALTER DATABASE/ROLE tests proposed per-database or per-user
- * defaults this way, and CREATE FUNCTION tests proposed function SET clauses
- * this way.  This is an interactive case, but it needs its own source value
- * because some assign hooks need to make different validity checks in this
- * case.  In particular, references to nonexistent database objects generally
+ * PGC_S_TEST is used when testing values to be used later.  For example,
+ * ALTER DATABASE/ROLE tests proposed per-database or per-user defaults this
+ * way, and CREATE FUNCTION tests proposed function SET clauses this way.
+ * This is an interactive case, but it needs its own source value because
+ * some assign hooks need to make different validity checks in this case.
+ * In particular, references to nonexistent database objects generally
  * shouldn't throw hard errors in this case, at most NOTICEs, since the
  * objects might exist by the time the setting is used for real.
  *