Address points made in post-commit review of replication origins.

Amit reviewed the replication origins patch and made some good
points. Address them. This fixes typos in error messages, docs and
comments and adds a missing error check (although in a
should-never-happen scenario).

Discussion: CAA4eK1JqUBVeWWKwUmBPryFaje4190ug0y-OAUHWQ6tD83V4xg@mail.gmail.com
Backpatch: 9.5, where replication origins were introduced.

doc/src/sgml/catalogs.sgml

@@ -5450,10 +5450,11 @@
       <entry><structfield>local_lsn</structfield></entry>
       <entry><type>pg_lsn</type></entry>
       <entry></entry>
-      <entry>This node's LSN that at
+      <entry>
-      which <literal>remote_lsn</literal> has been replicated. Used to
+       This node's LSN at which <literal>remote_lsn</literal> has
-      flush commit records before persisting data to disk when using
+       been replicated. Used to flush commit records before persisting
-      asynchronous commits.</entry>
+       data to disk when using asynchronous commits.
+      </entry>
      </row>
     </tbody>
    </tgroup>

doc/src/sgml/func.sgml

@@ -17421,7 +17421,7 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
         <indexterm>
          <primary>pg_replication_origin_session_progress</primary>
         </indexterm>
-        <literal><function>pg_replication_origin_progress(<parameter>flush</parameter> <type>bool</type>)</function></literal>
+        <literal><function>pg_replication_origin_session_progress(<parameter>flush</parameter> <type>bool</type>)</function></literal>
        </entry>
        <entry>
         pg_lsn

doc/src/sgml/replication-origins.sgml

@@ -57,7 +57,7 @@
   Using the replication origin infrastructure a session can be
   marked as replaying from a remote node (using the
   <link linkend="pg-replication-origin-session-setup"><function>pg_replication_origin_session_setup()</function></link>
-  function. Additionally the <acronym>LSN</acronym> and commit
+  function). Additionally the <acronym>LSN</acronym> and commit
   timestamp of every source transaction can be configured on a per
   transaction basis using
   <link linkend="pg-replication-origin-xact-setup"><function>pg_replication_origin_xact_setup()</function></link>.

src/backend/access/transam/xloginsert.c

@@ -73,7 +73,7 @@ static XLogRecData *mainrdata_head;
 static XLogRecData *mainrdata_last = (XLogRecData *) &mainrdata_head;
 static uint32 mainrdata_len;	/* total # of bytes in chain */
 
-/* Should te in-progress insertion log the origin */
+/* Should the in-progress insertion log the origin? */
 static bool include_origin = false;
 
 /*

src/backend/replication/logical/origin.c

@@ -313,7 +313,7 @@ replorigin_create(char *roname)
 	if (tuple == NULL)
 		ereport(ERROR,
 				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-				 errmsg("no free replication oid could be found")));
+				 errmsg("no free replication origin oid could be found")));
 
 	heap_freetuple(tuple);
 	return roident;
@@ -375,6 +375,10 @@ replorigin_drop(RepOriginId roident)
 	LWLockRelease(ReplicationOriginLock);
 
 	tuple = SearchSysCache1(REPLORIGIDENT, ObjectIdGetDatum(roident));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for replication origin with oid %u",
+			 roident);
+
 	simple_heap_delete(rel, &tuple->t_self);
 	ReleaseSysCache(tuple);
 
@@ -437,7 +441,7 @@ ReplicationOriginShmemSize(void)
 	Size		size = 0;
 
 	/*
-	 * XXX: max_replication_slots is arguablethe wrong thing to use here, here
+	 * XXX: max_replication_slots is arguably the wrong thing to use, as here
 	 * we keep the replay state of *remote* transactions. But for now it seems
 	 * sufficient to reuse it, lest we introduce a separate guc.
 	 */
@@ -523,7 +527,7 @@ CheckPointReplicationOrigin(void)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not remove file \"%s\": %m",
-						path)));
+						tmppath)));
 
 	/*
 	 * no other backend can perform this at the same time, we're protected by
@@ -799,12 +803,12 @@ replorigin_redo(XLogReaderState *record)
  * Tell the replication origin progress machinery that a commit from 'node'
  * that originated at the LSN remote_commit on the remote node was replayed
  * successfully and that we don't need to do so again. In combination with
- * setting up replorigin_sesssion_origin_lsn and replorigin_sesssion_origin that ensures we
+ * setting up replorigin_sesssion_origin_lsn and replorigin_sesssion_origin
- * won't loose knowledge about that after a crash if the transaction had a
+ * that ensures we won't loose knowledge about that after a crash if the
- * persistent effect (think of asynchronous commits).
+ * transaction had a persistent effect (think of asynchronous commits).
  *
  * local_commit needs to be a local LSN of the commit so that we can make sure
- * uppon a checkpoint that enough WAL has been persisted to disk.
+ * upon a checkpoint that enough WAL has been persisted to disk.
  *
  * Needs to be called with a RowExclusiveLock on pg_replication_origin,
  * unless running in recovery.
@@ -1249,7 +1253,6 @@ pg_replication_origin_session_reset(PG_FUNCTION_ARGS)
 
 	replorigin_session_reset();
 
-	/* FIXME */
 	replorigin_sesssion_origin = InvalidRepOriginId;
 	replorigin_sesssion_origin_lsn = InvalidXLogRecPtr;
 	replorigin_sesssion_origin_timestamp = 0;