Remove server support for the previous base backup protocol.

robertmhaas · robertmhaas · commit 0d4513b61386 · 2022-02-10T12:12:43.000-05:00
Commit cc333f3 added a new COPY sub-protocol for taking base backups, but retained support for the previous protocol. For the same reasons articulated in the message for commit 9cd28c2, remove support for the previous protocol from the server. Discussion: http://postgr.es/m/CA+TgmoazKcKUWtqVa0xZqSzbKgTH+X-aw4V7GyLD68EpDLMh8A@mail.gmail.com
diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
@@ -2634,13 +2634,8 @@ The commands accepted in replication mode are:
         <term><literal>TARGET</literal> <replaceable>'target'</replaceable></term>
         <listitem>
          <para>
-          Tells the server where to send the backup. If not specified,
-          the legacy base backup protocol will be used. Otherwise, the new
-          protocol will be used, as described below.
-         </para>
-
-         <para>
-          If the target is <literal>client</literal>, the backup data is
+          Tells the server where to send the backup.  If the target is
+          <literal>client</literal>, which is the default, the backup data is
           sent to the client. If it is <literal>server</literal>, the backup
           data is written to the server at the pathname specified by the
           <literal>TARGET_DETAIL</literal> option. If it is
@@ -2866,25 +2861,8 @@ The commands accepted in replication mode are:
      </para>
 
      <para>
-      After the second regular result set, one or more CopyOutResponse results
-      will be sent. If the <literal>TARGET</literal> option is not specified,
-      the legacy base backup protocol will be used. In this mode,
-      there will be one CopyOutResponse for the main directory, one for each
-      additional tablespace other than <literal>pg_default</literal> and
-      <literal>pg_global</literal>, and one for the backup manifested if
-      requested. The main data directory and any additional tablespaces will
-      be sent in tar format (following the <quote>ustar interchange
-      format</quote> specified in the POSIX 1003.1-2008 standard), and
-      the manifest will sent as a plain file.  Prior to
-      <literal>PostgreSQL</literal> 15, the server omitted the two trailing
-      blocks of zeroes specified in the standard, but this is no longer the
-      case.
-     </para>
- 
-     <para>
-      New applications should specify the <literal>TARGET</literal> option.
-      When that option is used, a single CopyOutResponse will be sent, and
-      the payload of each CopyData message will contain a message in one of
+      After the second regular result set, a CopyOutResponse will be sent.
+      The payload of each CopyData message will contain a message in one of
       the following formats:
      </para>
 
@@ -2898,6 +2876,10 @@ The commands accepted in replication mode are:
             <term>Byte1('n')</term>
             <listitem><para>
               Identifes the messaage as indicating the start of a new archive.
+              There will be one archive for the main data directory and one
+              for each additional tablespace; each will use tar format
+              (following the <quote>ustar interchange format</quote> specified
+              in the POSIX 1003.1-2008 standard).
             </para></listitem>
           </varlistentry>
           <varlistentry>
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
@@ -56,7 +56,6 @@
 typedef enum
 {
 	BACKUP_TARGET_BLACKHOLE,
-	BACKUP_TARGET_COMPAT,
 	BACKUP_TARGET_CLIENT,
 	BACKUP_TARGET_SERVER
 } backup_target_type;
@@ -719,7 +718,7 @@ parse_basebackup_options(List *options, basebackup_options *opt)
 	bool		o_compression_level = false;
 
 	MemSet(opt, 0, sizeof(*opt));
-	opt->target = BACKUP_TARGET_COMPAT;
+	opt->target = BACKUP_TARGET_CLIENT;
 	opt->manifest = MANIFEST_OPTION_NO;
 	opt->manifest_checksum_type = CHECKSUM_TYPE_CRC32C;
 	opt->compression = BACKUP_COMPRESSION_NONE;
@@ -992,16 +991,11 @@ SendBaseBackup(BaseBackupCmd *cmd)
 	 * protocol. If the target is specifically 'client' then set up to stream
 	 * the backup to the client; otherwise, it's being sent someplace else and
 	 * should not be sent to the client.
-	 *
-	 * If the TARGET option was not specified, we must fall back to the older
-	 * and less capable copy-tablespace protocol.
 	 */
 	if (opt.target == BACKUP_TARGET_CLIENT)
 		sink = bbsink_copystream_new(true);
-	else if (opt.target != BACKUP_TARGET_COMPAT)
-		sink = bbsink_copystream_new(false);
 	else
-		sink = bbsink_copytblspc_new();
+		sink = bbsink_copystream_new(false);
 
 	/*
 	 * If a non-default backup target is in use, arrange to send the data
@@ -1012,7 +1006,6 @@ SendBaseBackup(BaseBackupCmd *cmd)
 		case BACKUP_TARGET_BLACKHOLE:
 			/* Nothing to do, just discard data. */
 			break;
-		case BACKUP_TARGET_COMPAT:
 		case BACKUP_TARGET_CLIENT:
 			/* Nothing to do, handling above is sufficient. */
 			break;
diff --git a/src/backend/replication/basebackup_copy.c b/src/backend/replication/basebackup_copy.c
@@ -3,25 +3,18 @@
  * basebackup_copy.c
  *	  send basebackup archives using COPY OUT
  *
- * We have two different ways of doing this.
+ * We send a result set with information about the tabelspaces to be included
+ * in the backup before starting COPY OUT. Then, we start a single COPY OUT
+ * operation and transmits all the archives and the manifest if present during
+ * the course of that single COPY OUT. Each CopyData message begins with a
+ * type byte, allowing us to signal the start of a new archive, or the
+ * manifest, by some means other than ending the COPY stream. This also allows
+ * for future protocol extensions, since we can include arbitrary information
+ * in the message stream as long as we're certain that the client will know
+ * what to do with it.
  *
- * 'copytblspc' is an older method still supported for compatibility
- * with releases prior to v15. In this method, a separate COPY OUT
- * operation is used for each tablespace. The manifest, if it is sent,
- * uses an additional COPY OUT operation.
- *
- * 'copystream' sends a starts a single COPY OUT operation and transmits
- * all the archives and the manifest if present during the course of that
- * single COPY OUT. Each CopyData message begins with a type byte,
- * allowing us to signal the start of a new archive, or the manifest,
- * by some means other than ending the COPY stream. This also allows
- * this protocol to be extended more easily, since we can include
- * arbitrary information in the message stream as long as we're certain
- * that the client will know what to do with it.
- *
- * Regardless of which method is used, we sent a result set with
- * information about the tabelspaces to be included in the backup before
- * starting COPY OUT. This result has the same format in every method.
+ * An older method that sent each archive using a separate COPY OUT
+ * operation is no longer supported.
  *
  * Portions Copyright (c) 2010-2022, PostgreSQL Global Development Group
  *
@@ -87,20 +80,7 @@ static void bbsink_copystream_end_backup(bbsink *sink, XLogRecPtr endptr,
 										 TimeLineID endtli);
 static void bbsink_copystream_cleanup(bbsink *sink);
 
-static void bbsink_copytblspc_begin_backup(bbsink *sink);
-static void bbsink_copytblspc_begin_archive(bbsink *sink,
-											const char *archive_name);
-static void bbsink_copytblspc_archive_contents(bbsink *sink, size_t len);
-static void bbsink_copytblspc_end_archive(bbsink *sink);
-static void bbsink_copytblspc_begin_manifest(bbsink *sink);
-static void bbsink_copytblspc_manifest_contents(bbsink *sink, size_t len);
-static void bbsink_copytblspc_end_manifest(bbsink *sink);
-static void bbsink_copytblspc_end_backup(bbsink *sink, XLogRecPtr endptr,
-										 TimeLineID endtli);
-static void bbsink_copytblspc_cleanup(bbsink *sink);
-
 static void SendCopyOutResponse(void);
-static void SendCopyData(const char *data, size_t len);
 static void SendCopyDone(void);
 static void SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli);
 static void SendTablespaceList(List *tablespaces);
@@ -118,18 +98,6 @@ const bbsink_ops bbsink_copystream_ops = {
 	.cleanup = bbsink_copystream_cleanup
 };
 
-const bbsink_ops bbsink_copytblspc_ops = {
-	.begin_backup = bbsink_copytblspc_begin_backup,
-	.begin_archive = bbsink_copytblspc_begin_archive,
-	.archive_contents = bbsink_copytblspc_archive_contents,
-	.end_archive = bbsink_copytblspc_end_archive,
-	.begin_manifest = bbsink_copytblspc_begin_manifest,
-	.manifest_contents = bbsink_copytblspc_manifest_contents,
-	.end_manifest = bbsink_copytblspc_end_manifest,
-	.end_backup = bbsink_copytblspc_end_backup,
-	.cleanup = bbsink_copytblspc_cleanup
-};
-
 /*
  * Create a new 'copystream' bbsink.
  */
@@ -338,115 +306,6 @@ bbsink_copystream_cleanup(bbsink *sink)
 	/* Nothing to do. */
 }
 
-/*
- * Create a new 'copytblspc' bbsink.
- */
-bbsink *
-bbsink_copytblspc_new(void)
-{
-	bbsink	   *sink = palloc0(sizeof(bbsink));
-
-	*((const bbsink_ops **) &sink->bbs_ops) = &bbsink_copytblspc_ops;
-
-	return sink;
-}
-
-/*
- * Begin backup.
- */
-static void
-bbsink_copytblspc_begin_backup(bbsink *sink)
-{
-	bbsink_state *state = sink->bbs_state;
-
-	/* Create a suitable buffer. */
-	sink->bbs_buffer = palloc(sink->bbs_buffer_length);
-
-	/* Tell client the backup start location. */
-	SendXlogRecPtrResult(state->startptr, state->starttli);
-
-	/* Send client a list of tablespaces. */
-	SendTablespaceList(state->tablespaces);
-
-	/* Send a CommandComplete message */
-	pq_puttextmessage('C', "SELECT");
-}
-
-/*
- * Each archive is set as a separate stream of COPY data, and thus begins
- * with a CopyOutResponse message.
- */
-static void
-bbsink_copytblspc_begin_archive(bbsink *sink, const char *archive_name)
-{
-	SendCopyOutResponse();
-}
-
-/*
- * Each chunk of data within the archive is sent as a CopyData message.
- */
-static void
-bbsink_copytblspc_archive_contents(bbsink *sink, size_t len)
-{
-	SendCopyData(sink->bbs_buffer, len);
-}
-
-/*
- * The archive is terminated by a CopyDone message.
- */
-static void
-bbsink_copytblspc_end_archive(bbsink *sink)
-{
-	SendCopyDone();
-}
-
-/*
- * The backup manifest is sent as a separate stream of COPY data, and thus
- * begins with a CopyOutResponse message.
- */
-static void
-bbsink_copytblspc_begin_manifest(bbsink *sink)
-{
-	SendCopyOutResponse();
-}
-
-/*
- * Each chunk of manifest data is sent using a CopyData message.
- */
-static void
-bbsink_copytblspc_manifest_contents(bbsink *sink, size_t len)
-{
-	SendCopyData(sink->bbs_buffer, len);
-}
-
-/*
- * When we've finished sending the manifest, send a CopyDone message.
- */
-static void
-bbsink_copytblspc_end_manifest(bbsink *sink)
-{
-	SendCopyDone();
-}
-
-/*
- * Send end-of-backup wire protocol messages.
- */
-static void
-bbsink_copytblspc_end_backup(bbsink *sink, XLogRecPtr endptr,
-							 TimeLineID endtli)
-{
-	SendXlogRecPtrResult(endptr, endtli);
-}
-
-/*
- * Cleanup.
- */
-static void
-bbsink_copytblspc_cleanup(bbsink *sink)
-{
-	/* Nothing to do. */
-}
-
 /*
  * Send a CopyOutResponse message.
  */
@@ -461,15 +320,6 @@ SendCopyOutResponse(void)
 	pq_endmessage(&buf);
 }
 
-/*
- * Send a CopyData message.
- */
-static void
-SendCopyData(const char *data, size_t len)
-{
-	pq_putmessage('d', data, len);
-}
-
 /*
  * Send a CopyDone message.
  */
diff --git a/src/include/replication/basebackup_sink.h b/src/include/replication/basebackup_sink.h
@@ -283,7 +283,6 @@ extern void bbsink_forward_cleanup(bbsink *sink);
 
 /* Constructors for various types of sinks. */
 extern bbsink *bbsink_copystream_new(bool send_to_client);
-extern bbsink *bbsink_copytblspc_new(void);
 extern bbsink *bbsink_gzip_new(bbsink *next, int compresslevel);
 extern bbsink *bbsink_progress_new(bbsink *next, bool estimate_backup_size);
 extern bbsink *bbsink_server_new(bbsink *next, char *pathname);
