Revert "Allow on-line enabling and disabling of data checksums"

This reverts the backend sides of commit 1fde38be. I have, at least for now, left the pg_verify_checksums tool in place, as this tool can be very valuable without the rest of the patch as well, and since it's a read-only tool that only runs when the cluster is down it should be a lot safer.

Revert "Allow on-line enabling and disabling of data checksums"
This reverts the backend sides of commit 1fde38be. I have, at least for now, left the pg_verify_checksums tool in place, as this tool can be very valuable without the rest of the patch as well, and since it's a read-only tool that only runs when the cluster is down it should be a lot safer.
a228cc13 · Magnus Hagander · 03c11796 · a228cc13 · a228cc13 · a228cc13
Commit a228cc13 authored Apr 09, 2018 by Magnus Hagander
39 changed files
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -19566,71 +19566,6 @@ postgres=# SELECT * FROM pg_walfile_name_offset(pg_stop_backup());
  </sect2>
-  <sect2 id="functions-admin-checksum">
-   <title>Data Checksum Functions</title>
-   <para>
-    The functions shown in <xref linkend="functions-checksums-table" /> can
-    be used to enable or disable data checksums in a running cluster.
-    See <xref linkend="checksums" /> for details.
-   </para>
-   <table id="functions-checksums-table">
-    <title>Checksum <acronym>SQL</acronym> Functions</title>
-    <tgroup cols="3">
-     <thead>
-      <row>
-       <entry>Function</entry>
-       <entry>Return Type</entry>
-       <entry>Description</entry>
-      </row>
-     </thead>
-     <tbody>
-      <row>
-       <entry>
-        <indexterm>
-         <primary>pg_enable_data_checksums</primary>
-        </indexterm>
-        <literal><function>pg_enable_data_checksums(<optional><parameter>cost_delay</parameter> <type>int</type>, <parameter>cost_limit</parameter> <type>int</type></optional>)</function></literal>
-       </entry>
-       <entry>
-        void
-       </entry>
-       <entry>
-        <para>
-         Initiates data checksums for the cluster. This will switch the data checksums mode
-         to <literal>in progress</literal> and start a background worker that will process
-         all data in the database and enable checksums for it. When all data pages have had
-         checksums enabled, the cluster will automatically switch to checksums
-         <literal>on</literal>.
-        </para>
-        <para>
-         If <parameter>cost_delay</parameter> and <parameter>cost_limit</parameter> are
-         specified, the speed of the process is throttled using the same principles as
-         <link linkend="runtime-config-resource-vacuum-cost">Cost-based Vacuum Delay</link>.
-        </para>
-       </entry>
-      </row>
-      <row>
-       <entry>
-        <indexterm>
-         <primary>pg_disable_data_checksums</primary>
-        </indexterm>
-        <literal><function>pg_disable_data_checksums()</function></literal>
-       </entry>
-       <entry>
-        void
-       </entry>
-       <entry>
-        Disables data checksums for the cluster.
-       </entry>
-      </row>
-     </tbody>
-    </tgroup>
-   </table>
-  </sect2>
  <sect2 id="functions-admin-dbobject">
   <title>Database Object Management Functions</title>

--- a/doc/src/sgml/ref/initdb.sgml
+++ b/doc/src/sgml/ref/initdb.sgml
@@ -214,9 +214,9 @@ PostgreSQL documentation
       <para>
        Use checksums on data pages to help detect corruption by the
        I/O system that would otherwise be silent. Enabling checksums
-        may incur a noticeable performance penalty. If set, checksums
+        may incur a noticeable performance penalty. This option can only
-        are calculated for all objects, in all databases. See
+        be set during initialization, and cannot be changed later. If
-        <xref linkend="checksums" /> for details.
+        set, checksums are calculated for all objects, in all databases.
       </para>
      </listitem>
     </varlistentry>

--- a/doc/src/sgml/reference.sgml
+++ b/doc/src/sgml/reference.sgml
@@ -284,7 +284,6 @@
   &pgtestfsync;
   &pgtesttiming;
   &pgupgrade;
-   &pgVerifyChecksums;
   &pgwaldump;
   &postgres;
   &postmaster;

--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -230,87 +230,6 @@
  </para>
 </sect1>
- <sect1 id="checksums">
-  <title>Data checksums</title>
-  <indexterm>
-   <primary>checksums</primary>
-  </indexterm>
-  <para>
-   Data pages are not checksum protected by default, but this can optionally be enabled for a cluster.
-   When enabled, each data page will be assigned a checksum that is updated when the page is
-   written and verified every time the page is read. Only data pages are protected by checksums,
-   internal data structures and temporary files are not.
-  </para>
-  <para>
-   Checksums are normally enabled when the cluster is initialized using
-   <link linkend="app-initdb-data-checksums"><application>initdb</application></link>. They
-   can also be enabled or disabled at runtime. In all cases, checksums are enabled or disabled
-   at the full cluster level, and cannot be specified individually for databases or tables.
-  </para>
-  <para>
-   The current state of checksums in the cluster can be verified by viewing the value
-   of the read-only configuration variable <xref linkend="guc-data-checksums" /> by
-   issuing the command <command>SHOW data_checksums</command>.
-  </para>
-  <para>
-   When attempting to recover from corrupt data it may be necessary to bypass the checksum
-   protection in order to recover data. To do this, temporarily set the configuration parameter
-   <xref linkend="guc-ignore-checksum-failure" />.
-  </para>
-  <sect2 id="checksums-enable-disable">
-   <title>On-line enabling of checksums</title>
-   <para>
-    Checksums can be enabled or disabled online, by calling the appropriate
-    <link linkend="functions-admin-checksum">functions</link>.
-    Disabling of checksums takes effect immediately when the function is called.
-   </para>
-   <para>
-    Enabling checksums will put the cluster in <literal>inprogress</literal> mode.
-    During this time, checksums will be written but not verified. In addition to
-    this, a background worker process is started that enables checksums on all
-    existing data in the cluster. Once this worker has completed processing all
-    databases in the cluster, the checksum mode will automatically switch to
-    <literal>on</literal>.
-   </para>
-   <para>
-    The process will initially wait for all open transactions to finish before
-    it starts, so that it can be certain that there are no tables that have been
-    created inside a transaction that has not committed yet and thus would not
-    be visible to the process enabling checksums. It will also, for each database,
-    wait for all pre-existing temporary tables to get removed before it finishes.
-    If long-lived temporary tables are used in the application it may be necessary
-    to terminate these application connections to allow the process to complete.
-    Information about open transactions and connections with temporary tables is
-    written to log.
-   </para>
-   <para>
-    If the cluster is stopped while in <literal>inprogress</literal> mode, for
-    any reason, then this process must be restarted manually. To do this,
-    re-execute the function <function>pg_enable_data_checksums()</function>
-    once the cluster has been restarted. It is not possible to resume the work,
-    the process has to start over and re-process the cluster.
-   </para>
-   <note>
-    <para>
-     Enabling checksums can cause significant I/O to the system, as most of the
-     database pages will need to be rewritten, and will be written both to the
-     data files and the WAL.
-    </para>
-   </note>
-  </sect2>
- </sect1>
  <sect1 id="wal-intro">
   <title>Write-Ahead Logging (<acronym>WAL</acronym>)</title>

--- a/src/backend/access/rmgrdesc/xlogdesc.c
+++ b/src/backend/access/rmgrdesc/xlogdesc.c
@@ -17,7 +17,6 @@
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "catalog/pg_control.h"
-#include "storage/bufpage.h"
 #include "utils/guc.h"
 #include "utils/timestamp.h"
@@ -138,18 +137,6 @@ xlog_desc(StringInfo buf, XLogReaderState *record)
 						 xlrec.ThisTimeLineID, xlrec.PrevTimeLineID,
 						 timestamptz_to_str(xlrec.end_time));
 	}
-	else if (info == XLOG_CHECKSUMS)
-	{
-		xl_checksum_state xlrec;
-		memcpy(&xlrec, rec, sizeof(xl_checksum_state));
-		if (xlrec.new_checksumtype == PG_DATA_CHECKSUM_VERSION)
-			appendStringInfo(buf, "on");
-		else if (xlrec.new_checksumtype == PG_DATA_CHECKSUM_INPROGRESS_VERSION)
-			appendStringInfo(buf, "inprogress");
-		else
-			appendStringInfo(buf, "off");
-	}
 }
 const char *
@@ -195,9 +182,6 @@ xlog_identify(uint8 info)
 		case XLOG_FPI_FOR_HINT:
 			id = "FPI_FOR_HINT";
 			break;
-		case XLOG_CHECKSUMS:
-			id = "CHECKSUMS";
-			break;
 	}
 	return id;

--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -856,7 +856,6 @@ static void SetLatestXTime(TimestampTz xtime);
 static void SetCurrentChunkStartTime(TimestampTz xtime);
 static void CheckRequiredParameterValues(void);
 static void XLogReportParameters(void);
-static void XlogChecksums(ChecksumType new_type);
 static void checkTimeLineSwitch(XLogRecPtr lsn, TimeLineID newTLI,
 					TimeLineID prevTLI);
 static void LocalSetXLogInsertAllowed(void);
@@ -1034,7 +1033,7 @@ XLogInsertRecord(XLogRecData *rdata,
 		Assert(RedoRecPtr < Insert->RedoRecPtr);
 		RedoRecPtr = Insert->RedoRecPtr;
 	}
-	doPageWrites = (Insert->fullPageWrites || Insert->forcePageWrites || DataChecksumsInProgress());
+	doPageWrites = (Insert->fullPageWrites || Insert->forcePageWrites);
 	if (fpw_lsn != InvalidXLogRecPtr && fpw_lsn <= RedoRecPtr && doPageWrites)
 	{
@@ -4674,6 +4673,10 @@ ReadControlFile(void)
 		(SizeOfXLogLongPHD - SizeOfXLogShortPHD);
 	CalculateCheckpointSegments();
+	/* Make the initdb settings visible as GUC variables, too */
+	SetConfigOption("data_checksums", DataChecksumsEnabled() ? "yes" : "no",
+					PGC_INTERNAL, PGC_S_OVERRIDE);
 }
 void
@@ -4745,90 +4748,12 @@ GetMockAuthenticationNonce(void)
 * Are checksums enabled for data pages?
 */
 bool
-DataChecksumsNeedWrite(void)
+DataChecksumsEnabled(void)
 {
 	Assert(ControlFile != NULL);
 	return (ControlFile->data_checksum_version > 0);
 }
-bool
-DataChecksumsNeedVerify(void)
-{
-	Assert(ControlFile != NULL);
-	/*
-	 * Only verify checksums if they are fully enabled in the cluster. In
-	 * inprogress state they are only updated, not verified.
-	 */
-	return (ControlFile->data_checksum_version == PG_DATA_CHECKSUM_VERSION);
-}
-bool
-DataChecksumsInProgress(void)
-{
-	Assert(ControlFile != NULL);
-	return (ControlFile->data_checksum_version == PG_DATA_CHECKSUM_INPROGRESS_VERSION);
-}
-void
-SetDataChecksumsInProgress(void)
-{
-	Assert(ControlFile != NULL);
-	if (ControlFile->data_checksum_version > 0)
-		return;
-	XlogChecksums(PG_DATA_CHECKSUM_INPROGRESS_VERSION);
-	LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
-	ControlFile->data_checksum_version = PG_DATA_CHECKSUM_INPROGRESS_VERSION;
-	UpdateControlFile();
-	LWLockRelease(ControlFileLock);
-}
-void
-SetDataChecksumsOn(void)
-{
-	Assert(ControlFile != NULL);
-	LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
-	if (ControlFile->data_checksum_version != PG_DATA_CHECKSUM_INPROGRESS_VERSION)
-	{
-		LWLockRelease(ControlFileLock);
-		elog(ERROR, "Checksums not in inprogress mode");
-	}
-	ControlFile->data_checksum_version = PG_DATA_CHECKSUM_VERSION;
-	UpdateControlFile();
-	LWLockRelease(ControlFileLock);
-	XlogChecksums(PG_DATA_CHECKSUM_VERSION);
-}
-void
-SetDataChecksumsOff(void)
-{
-	LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
-	ControlFile->data_checksum_version = 0;
-	UpdateControlFile();
-	LWLockRelease(ControlFileLock);
-	XlogChecksums(0);
-}
-/* guc hook */
-const char *
-show_data_checksums(void)
-{
-	if (ControlFile->data_checksum_version == PG_DATA_CHECKSUM_VERSION)
-		return "on";
-	else if (ControlFile->data_checksum_version == PG_DATA_CHECKSUM_INPROGRESS_VERSION)
-		return "inprogress";
-	else
-		return "off";
-}
 /*
 * Returns a fake LSN for unlogged relations.
 *
@@ -7863,16 +7788,6 @@ StartupXLOG(void)
 	 */
 	CompleteCommitTsInitialization();
-	/*
-	 * If we reach this point with checksums in inprogress state, we notify
-	 * the user that they need to manually restart the process to enable
-	 * checksums.
-	 */
-	if (ControlFile->data_checksum_version == PG_DATA_CHECKSUM_INPROGRESS_VERSION)
-		ereport(WARNING,
-				(errmsg("checksum state is \"inprogress\" with no worker"),
-				 errhint("Either disable or enable checksums by calling the pg_disable_data_checksums() or pg_enable_data_checksums() functions.")));
 	/*
 	 * All done with end-of-recovery actions.
 	 *
@@ -9626,22 +9541,6 @@ XLogReportParameters(void)
 	}
 }
-/*
- * Log the new state of checksums
- */
-static void
-XlogChecksums(ChecksumType new_type)
-{
-	xl_checksum_state xlrec;
-	xlrec.new_checksumtype = new_type;
-	XLogBeginInsert();
-	XLogRegisterData((char *) &xlrec, sizeof(xl_checksum_state));
-	XLogInsert(RM_XLOG_ID, XLOG_CHECKSUMS);
-}
 /*
 * Update full_page_writes in shared memory, and write an
 * XLOG_FPW_CHANGE record if necessary.
@@ -10070,17 +9969,6 @@ xlog_redo(XLogReaderState *record)
 		/* Keep track of full_page_writes */
 		lastFullPageWrites = fpw;
 	}
-	else if (info == XLOG_CHECKSUMS)
-	{
-		xl_checksum_state state;
-		memcpy(&state, XLogRecGetData(record), sizeof(xl_checksum_state));
-		LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
-		ControlFile->data_checksum_version = state.new_checksumtype;
-		UpdateControlFile();
-		LWLockRelease(ControlFileLock);
-	}
 }
 #ifdef WAL_DEBUG

--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -24,7 +24,6 @@
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
-#include "postmaster/checksumhelper.h"
 #include "replication/walreceiver.h"
 #include "storage/smgr.h"
 #include "utils/builtins.h"
@@ -699,61 +698,3 @@ pg_backup_start_time(PG_FUNCTION_ARGS)
 	PG_RETURN_DATUM(xtime);
 }
-/*
- * Disables checksums for the cluster, unless already disabled.
- *
- * Has immediate effect - the checksums are set to off right away.
- */
-Datum
-disable_data_checksums(PG_FUNCTION_ARGS)
-{
-	/*
-	 * If we don't need to write new checksums, then clearly they are already
-	 * disabled.
-	 */
-	if (!DataChecksumsNeedWrite())
-		ereport(ERROR,
-				(errmsg("data checksums already disabled")));
-	ShutdownChecksumHelperIfRunning();
-	SetDataChecksumsOff();
-	PG_RETURN_VOID();
-}
-/*
- * Enables checksums for the cluster, unless already enabled.
- *
- * Supports vacuum-like cost-based throttling, to limit system load.
- * Starts a background worker that updates checksums on existing data.
- */
-Datum
-enable_data_checksums(PG_FUNCTION_ARGS)
-{
-	int			cost_delay = PG_GETARG_INT32(0);
-	int			cost_limit = PG_GETARG_INT32(1);
-	if (cost_delay < 0)
-		ereport(ERROR,
-				(errmsg("cost delay cannot be less than zero")));
-	if (cost_limit <= 0)
-		ereport(ERROR,
-				(errmsg("cost limit must be a positive value")));
-	/*
-	 * Allow state change from "off" or from "inprogress", since this is how
-	 * we restart the worker if necessary.
-	 */
-	if (DataChecksumsNeedVerify())
-		ereport(ERROR,
-				(errmsg("data checksums already enabled")));
-	SetDataChecksumsInProgress();
-	if (!StartChecksumHelperLauncher(cost_delay, cost_limit))
-		ereport(ERROR,
-				(errmsg("failed to start checksum helper process")));
-	PG_RETURN_VOID();
-}
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1027,11 +1027,6 @@ CREATE OR REPLACE FUNCTION pg_stop_backup (
  RETURNS SETOF record STRICT VOLATILE LANGUAGE internal as 'pg_stop_backup_v2'
  PARALLEL RESTRICTED;
-CREATE OR REPLACE FUNCTION pg_enable_data_checksums (
-        cost_delay int DEFAULT 0, cost_limit int DEFAULT 100)
-  RETURNS void STRICT VOLATILE LANGUAGE internal AS 'enable_data_checksums'
-  PARALLEL RESTRICTED;
 -- legacy definition for compatibility with 9.3
 CREATE OR REPLACE FUNCTION
  json_populate_record(base anyelement, from_json json, use_json_as_text boolean DEFAULT false)

--- a/src/backend/postmaster/Makefile
+++ b/src/backend/postmaster/Makefile
@@ -12,8 +12,7 @@ subdir = src/backend/postmaster
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
-OBJS = autovacuum.o bgworker.o bgwriter.o checkpointer.o checksumhelper.o \
+OBJS = autovacuum.o bgworker.o bgwriter.o checkpointer.o fork_process.o \
-	fork_process.o pgarch.o pgstat.o postmaster.o startup.o syslogger.o \
+	pgarch.o pgstat.o postmaster.o startup.o syslogger.o walwriter.o
-	walwriter.o
 include $(top_srcdir)/src/backend/common.mk
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -20,7 +20,6 @@
 #include "pgstat.h"
 #include "port/atomics.h"
 #include "postmaster/bgworker_internals.h"
-#include "postmaster/checksumhelper.h"
 #include "postmaster/postmaster.h"
 #include "replication/logicallauncher.h"
 #include "replication/logicalworker.h"
@@ -130,12 +129,6 @@ static const struct
 	},
 	{
 		"ApplyWorkerMain", ApplyWorkerMain
-	},
-	{
-		"ChecksumHelperLauncherMain", ChecksumHelperLauncherMain
-	},
-	{
-		"ChecksumHelperWorkerMain", ChecksumHelperWorkerMain
 	}
 };

--- a/src/backend/postmaster/checksumhelper.c
+++ b/src/backend/postmaster/checksumhelper.c
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -4125,11 +4125,6 @@ pgstat_get_backend_desc(BackendType backendType)
 		case B_WAL_WRITER:
 			backendDesc = "walwriter";
 			break;
-		case B_CHECKSUMHELPER_LAUNCHER:
-			backendDesc = "checksumhelper launcher";
-			break;
-		case B_CHECKSUMHELPER_WORKER:
-			backendDesc = "checksumhelper worker";
 	}
 	return backendDesc;

--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -1384,7 +1384,7 @@ sendFile(const char *readfilename, const char *tarfilename, struct stat *statbuf
 	_tarWriteHeader(tarfilename, NULL, statbuf, false);
-	if (!noverify_checksums && DataChecksumsNeedVerify())
+	if (!noverify_checksums && DataChecksumsEnabled())
 	{
 		char	   *filename;

--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -199,7 +199,6 @@ DecodeXLogOp(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 		case XLOG_FPW_CHANGE:
 		case XLOG_FPI_FOR_HINT:
 		case XLOG_FPI:
-		case XLOG_CHECKSUMS:
 			break;
 		default:
 			elog(ERROR, "unexpected RM_XLOG_ID record type: %u", info);

--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -27,7 +27,6 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/bgworker_internals.h"
 #include "postmaster/bgwriter.h"
-#include "postmaster/checksumhelper.h"
 #include "postmaster/postmaster.h"
 #include "replication/logicallauncher.h"
 #include "replication/slot.h"
@@ -262,7 +261,6 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
 	WalSndShmemInit();
 	WalRcvShmemInit();
 	ApplyLauncherShmemInit();
-	ChecksumHelperShmemInit();
 	/*
 	 * Set up other modules that need some shared memory space

--- a/src/backend/storage/page/README
+++ b/src/backend/storage/page/README
@@ -9,8 +9,7 @@ have a very low measured incidence according to research on large server farms,
 http://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf, discussed
 2010/12/22 on -hackers list.
-Checksums can be enabled at initdb time, but can also be turned on and off
+Current implementation requires this be enabled system-wide at initdb time.
-using pg_enable_data_checksums()/pg_disable_data_checksums() at runtime.
 The checksum is not valid at all times on a data page!!
 The checksum is valid when the page leaves the shared pool and is checked

--- a/src/backend/storage/page/bufpage.c
+++ b/src/backend/storage/page/bufpage.c
@@ -93,7 +93,7 @@ PageIsVerified(Page page, BlockNumber blkno)
 	 */
 	if (!PageIsNew(page))
 	{
-		if (DataChecksumsNeedVerify())
+		if (DataChecksumsEnabled())
 		{
 			checksum = pg_checksum_page((char *) page, blkno);
@@ -1168,7 +1168,7 @@ PageSetChecksumCopy(Page page, BlockNumber blkno)
 	static char *pageCopy = NULL;
 	/* If we don't need a checksum, just return the passed-in data */
-	if (PageIsNew(page) || !DataChecksumsNeedWrite())
+	if (PageIsNew(page) || !DataChecksumsEnabled())
 		return (char *) page;
 	/*
@@ -1195,7 +1195,7 @@ void
 PageSetChecksumInplace(Page page, BlockNumber blkno)
 {
 	/* If we don't need a checksum, just return */
-	if (PageIsNew(page) || !DataChecksumsNeedWrite())
+	if (PageIsNew(page) || !DataChecksumsEnabled())
 		return;
 	((PageHeader) page)->pd_checksum = pg_checksum_page((char *) page, blkno);

--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -32,7 +32,6 @@
 #include "access/transam.h"
 #include "access/twophase.h"
 #include "access/xact.h"
-#include "access/xlog.h"
 #include "access/xlog_internal.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_authid.h"
@@ -69,7 +68,6 @@
 #include "replication/walreceiver.h"
 #include "replication/walsender.h"
 #include "storage/bufmgr.h"
-#include "storage/checksum.h"
 #include "storage/dsm_impl.h"
 #include "storage/standby.h"
 #include "storage/fd.h"
@@ -422,17 +420,6 @@ static const struct config_enum_entry password_encryption_options[] = {
 	{NULL, 0, false}
 };
-/*
- * data_checksum used to be a boolean, but was only set by initdb so there is
- * no need to support variants of boolean input.
- */
-static const struct config_enum_entry data_checksum_options[] = {
-	{"on", DATA_CHECKSUMS_ON, true},
-	{"off", DATA_CHECKSUMS_OFF, true},
-	{"inprogress", DATA_CHECKSUMS_INPROGRESS, true},
-	{NULL, 0, false}
-};
 /*
 * Options for enum values stored in other modules
 */
@@ -528,7 +515,7 @@ static int	max_identifier_length;
 static int	block_size;
 static int	segment_size;
 static int	wal_block_size;
-static int	data_checksums_tmp; /* only accessed locally! */
+static bool data_checksums;
 static bool integer_datetimes;
 static bool assert_enabled;
@@ -1697,6 +1684,17 @@ static struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
+	{
+		{"data_checksums", PGC_INTERNAL, PRESET_OPTIONS,
+			gettext_noop("Shows whether data checksums are turned on for this cluster."),
+			NULL,
+			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
+		},
+		&data_checksums,
+		false,
+		NULL, NULL, NULL
+	},
 	{
 		{"syslog_sequence_numbers", PGC_SIGHUP, LOGGING_WHERE,
 			gettext_noop("Add sequence number to syslog messages to avoid duplicate suppression."),
@@ -4129,17 +4127,6 @@ static struct config_enum ConfigureNamesEnum[] =
 		NULL, NULL, NULL
 	},
-	{
-		{"data_checksums", PGC_INTERNAL, PRESET_OPTIONS,
-			gettext_noop("Shows whether data checksums are turned on for this cluster."),
-			NULL,
-			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE
-		},
-		&data_checksums_tmp,
-		DATA_CHECKSUMS_OFF, data_checksum_options,
-		NULL, NULL, show_data_checksums
-	},
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, 0, NULL, NULL, NULL, NULL

--- a/src/bin/pg_upgrade/controldata.c
+++ b/src/bin/pg_upgrade/controldata.c
@@ -590,15 +590,6 @@ check_control_data(ControlData *oldctrl,
 	 * check_for_isn_and_int8_passing_mismatch().
 	 */
-	/*
-	 * If checksums have been turned on in the old cluster, but the
-	 * checksumhelper have yet to finish, then disallow upgrading. The user
-	 * should either let the process finish, or turn off checksums, before
-	 * retrying.
-	 */
-	if (oldctrl->data_checksum_version == 2)
-		pg_fatal("transition to data checksums not completed in old cluster\n");
 	/*
 	 * We might eventually allow upgrades from checksum to no-checksum
 	 * clusters.

--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -226,7 +226,7 @@ typedef struct
 	uint32		large_object;
 	bool		date_is_int;
 	bool		float8_pass_by_value;
-	uint32		data_checksum_version;
+	bool		data_checksum_version;
 } ControlData;
 /*

--- a/src/bin/pg_verify_checksums/pg_verify_checksums.c
+++ b/src/bin/pg_verify_checksums/pg_verify_checksums.c
@@ -307,9 +307,6 @@ main(int argc, char *argv[])
 	printf(_("Data checksum version: %d\n"), ControlFile->data_checksum_version);
 	printf(_("Files scanned:  %" INT64_MODIFIER "d\n"), files);
 	printf(_("Blocks scanned: %" INT64_MODIFIER "d\n"), blocks);
-	if (ControlFile->data_checksum_version == PG_DATA_CHECKSUM_INPROGRESS_VERSION)
-		printf(_("Blocks left in progress: %" INT64_MODIFIER "d\n"), badblocks);
-	else
 	printf(_("Bad checksums:  %" INT64_MODIFIER "d\n"), badblocks);
 	if (badblocks > 0)

--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -154,7 +154,7 @@ extern PGDLLIMPORT int wal_level;
 * of the bits make it to disk, but the checksum wouldn't match.  Also WAL-log
 * them if forced by wal_log_hints=on.
 */
-#define XLogHintBitIsNeeded() (DataChecksumsNeedWrite() || wal_log_hints)
+#define XLogHintBitIsNeeded() (DataChecksumsEnabled() || wal_log_hints)
 /* Do we need to WAL-log information required only for Hot Standby and logical replication? */
 #define XLogStandbyInfoActive() (wal_level >= WAL_LEVEL_REPLICA)
@@ -257,13 +257,7 @@ extern char *XLogFileNameP(TimeLineID tli, XLogSegNo segno);
 extern void UpdateControlFile(void);
 extern uint64 GetSystemIdentifier(void);
 extern char *GetMockAuthenticationNonce(void);
-extern bool DataChecksumsNeedWrite(void);
+extern bool DataChecksumsEnabled(void);
-extern bool DataChecksumsNeedVerify(void);
-extern bool DataChecksumsInProgress(void);
-extern void SetDataChecksumsInProgress(void);
-extern void SetDataChecksumsOn(void);
-extern void SetDataChecksumsOff(void);
-extern const char *show_data_checksums(void);
 extern XLogRecPtr GetFakeLSNForUnloggedRel(void);
 extern Size XLOGShmemSize(void);
 extern void XLOGShmemInit(void);

--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -25,7 +25,6 @@
 #include "lib/stringinfo.h"
 #include "pgtime.h"
 #include "storage/block.h"
-#include "storage/checksum.h"
 #include "storage/relfilenode.h"
@@ -241,12 +240,6 @@ typedef struct xl_restore_point
 	char		rp_name[MAXFNAMELEN];
 } xl_restore_point;
-/* Information logged when checksum level is changed */
-typedef struct xl_checksum_state
-{
-	ChecksumType new_checksumtype;
-}			xl_checksum_state;
 /* End of recovery mark, when we don't do an END_OF_RECOVERY checkpoint */
 typedef struct xl_end_of_recovery
 {

--- a/src/include/catalog/pg_control.h
+++ b/src/include/catalog/pg_control.h
@@ -76,7 +76,6 @@ typedef struct CheckPoint
 #define XLOG_END_OF_RECOVERY			0x90
 #define XLOG_FPI_FOR_HINT				0xA0
 #define XLOG_FPI						0xB0
-#define XLOG_CHECKSUMS					0xC0
 /*

--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -10169,14 +10169,6 @@
  proargnames => '{max_data_alignment,database_block_size,blocks_per_segment,wal_block_size,bytes_per_wal_segment,max_identifier_length,max_index_columns,max_toast_chunk_size,large_object_chunk_size,float4_pass_by_value,float8_pass_by_value,data_page_checksum_version}',
  prosrc => 'pg_control_init' },
-{ oid => '3996', descr => 'disable data checksums',
-  proname => 'pg_disable_data_checksums', provolatile => 'v',
-  prorettype => 'void', proargtypes => '', prosrc => 'disable_data_checksums' },
-{ oid => '3998', descr => 'enable data checksums',
-  proname => 'pg_enable_data_checksums', provolatile => 'v',
-  prorettype => 'void', proargtypes => 'int4 int4',
-  proargnames => '{cost_delay,cost_limit}', prosrc => 'enable_data_checksums' },
 # collation management functions
 { oid => '3445', descr => 'import collations from operating system',
  proname => 'pg_import_system_collations', procost => '100',

--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -710,9 +710,7 @@ typedef enum BackendType
 	B_STARTUP,
 	B_WAL_RECEIVER,
 	B_WAL_SENDER,
-	B_WAL_WRITER,
+	B_WAL_WRITER
-	B_CHECKSUMHELPER_LAUNCHER,
-	B_CHECKSUMHELPER_WORKER
 } BackendType;

--- a/src/include/postmaster/checksumhelper.h
+++ b/src/include/postmaster/checksumhelper.h
-/*-------------------------------------------------------------------------
- *
- * checksumhelper.h
- *	  header file for checksum helper background worker
- *
- *
- * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * src/include/postmaster/checksumhelper.h
- *
- *-------------------------------------------------------------------------
- */
-#ifndef CHECKSUMHELPER_H
-#define CHECKSUMHELPER_H
-/* Shared memory */
-extern Size ChecksumHelperShmemSize(void);
-extern void ChecksumHelperShmemInit(void);
-/* Start the background processes for enabling checksums */
-bool		StartChecksumHelperLauncher(int cost_delay, int cost_limit);
-/* Shutdown the background processes, if any */
-void		ShutdownChecksumHelperIfRunning(void);
-/* Background worker entrypoints */
-void		ChecksumHelperLauncherMain(Datum arg);
-void		ChecksumHelperWorkerMain(Datum arg);
-#endif							/* CHECKSUMHELPER_H */
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -194,7 +194,6 @@ typedef PageHeaderData *PageHeader;
 */
 #define PG_PAGE_LAYOUT_VERSION		4
 #define PG_DATA_CHECKSUM_VERSION	1
-#define PG_DATA_CHECKSUM_INPROGRESS_VERSION		2
 /* ----------------------------------------------------------------
 *						page support macros

--- a/src/include/storage/checksum.h
+++ b/src/include/storage/checksum.h
@@ -15,13 +15,6 @@
 #include "storage/block.h"
-typedef enum ChecksumType
-{
-	DATA_CHECKSUMS_OFF = 0,
-	DATA_CHECKSUMS_ON,
-	DATA_CHECKSUMS_INPROGRESS
-}			ChecksumType;
 /*
 * Compute the checksum for a Postgres page.  The page must be aligned on a
 * 4-byte boundary.

--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -12,8 +12,7 @@ subdir = src/test
 top_builddir = ../..
 include $(top_builddir)/src/Makefile.global
-SUBDIRS = perl regress isolation modules authentication recovery subscription \
+SUBDIRS = perl regress isolation modules authentication recovery subscription
-			checksum
 # Test suites that are not safe by default but can be run if selected
 # by the user via the whitespace-separated list in variable

--- a/src/test/checksum/.gitignore
+++ b/src/test/checksum/.gitignore
-# Generated by test suite
-/tmp_check/
--- a/src/test/checksum/Makefile
+++ b/src/test/checksum/Makefile
-#-------------------------------------------------------------------------
-#
-# Makefile for src/test/checksum
-#
-# Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
-# Portions Copyright (c) 1994, Regents of the University of California
-#
-# src/test/checksum/Makefile
-#
-#-------------------------------------------------------------------------
-subdir = src/test/checksum
-top_builddir = ../../..
-include $(top_builddir)/src/Makefile.global
-check:
-	$(prove_check)
-installcheck:
-	$(prove_installcheck)
-clean distclean maintainer-clean:
-	rm -rf tmp_check
--- a/src/test/checksum/README
+++ b/src/test/checksum/README
-src/test/checksum/README
-Regression tests for data checksums
-===================================
-This directory contains a test suite for enabling data checksums
-in a running cluster with streaming replication.
-Running the tests
-=================
-    make check
-or
-    make installcheck
-NOTE: This creates a temporary installation (in the case of "check"),
-with multiple nodes, be they master or standby(s) for the purpose of
-the tests.
-NOTE: This requires the --enable-tap-tests argument to configure.
--- a/src/test/checksum/t/001_standby_checksum.pl
+++ b/src/test/checksum/t/001_standby_checksum.pl
-# Test suite for testing enabling data checksums with streaming replication
-use strict;
-use warnings;
-use PostgresNode;
-use TestLib;
-use Test::More tests => 10;
-my $MAX_TRIES = 30;
-# Initialize master node
-my $node_master = get_new_node('master');
-$node_master->init(allows_streaming => 1);
-$node_master->start;
-my $backup_name = 'my_backup';
-# Take backup
-$node_master->backup($backup_name);
-# Create streaming standby linking to master
-my $node_standby_1 = get_new_node('standby_1');
-$node_standby_1->init_from_backup($node_master, $backup_name,
-	has_streaming => 1);
-$node_standby_1->start;
-# Create some content on master to have un-checksummed data in the cluster
-$node_master->safe_psql('postgres',
-	"CREATE TABLE t AS SELECT generate_series(1,10000) AS a;");
-# Wait for standbys to catch up
-$node_master->wait_for_catchup($node_standby_1, 'replay',
-	$node_master->lsn('insert'));
-# Check that checksums are turned off
-my $result = $node_master->safe_psql('postgres',
-	"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-is($result, "off", 'ensure checksums are turned off on master');
-$result = $node_standby_1->safe_psql('postgres',
-	"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-is($result, "off", 'ensure checksums are turned off on standby_1');
-# Enable checksums for the cluster
-$node_master->safe_psql('postgres', "SELECT pg_enable_data_checksums();");
-# Ensure that the master has switched to inprogress immediately
-$result = $node_master->safe_psql('postgres',
-	"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-is($result, "inprogress", 'ensure checksums are in progress on master');
-# Wait for checksum enable to be replayed
-$node_master->wait_for_catchup($node_standby_1, 'replay');
-# Ensure that the standby has switched to inprogress
-$result = $node_standby_1->safe_psql('postgres',
-	"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-is($result, "inprogress", 'ensure checksums are in progress on standby_1');
-# Insert some more data which should be checksummed on INSERT
-$node_master->safe_psql('postgres',
-	"INSERT INTO t VALUES (generate_series(1,10000));");
-# Wait for checksums enabled on the master
-for (my $i = 0; $i < $MAX_TRIES; $i++)
-{
-	$result = $node_master->safe_psql('postgres',
-		"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-	last if ($result eq 'on');
-	sleep(1);
-}
-is ($result, "on", 'ensure checksums are enabled on master');
-# Wait for checksums enabled on the standby
-for (my $i = 0; $i < $MAX_TRIES; $i++)
-{
-	$result = $node_standby_1->safe_psql('postgres',
-		"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-	last if ($result eq 'on');
-	sleep(1);
-}
-is ($result, "on", 'ensure checksums are enabled on standby');
-$result = $node_master->safe_psql('postgres', "SELECT count(a) FROM t");
-is ($result, "20000", 'ensure we can safely read all data with checksums');
-# Disable checksums and ensure it's propagated to standby and that we can
-# still read all data
-$node_master->safe_psql('postgres', "SELECT pg_disable_data_checksums();");
-$result = $node_master->safe_psql('postgres',
-	"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-is($result, "off", 'ensure checksums are in progress on master');
-# Wait for checksum disable to be replayed
-$node_master->wait_for_catchup($node_standby_1, 'replay');
-# Ensure that the standby has switched to off
-$result = $node_standby_1->safe_psql('postgres',
-	"SELECT setting FROM pg_catalog.pg_settings WHERE name = 'data_checksums';");
-is($result, "off", 'ensure checksums are in progress on standby_1');
-$result = $node_master->safe_psql('postgres', "SELECT count(a) FROM t");
-is ($result, "20000", 'ensure we can safely read all data without checksums');
--- a/src/test/isolation/expected/checksum_cancel.out
+++ b/src/test/isolation/expected/checksum_cancel.out
-Parsed test spec with 2 sessions
-starting permutation: c_verify_checksums_off r_seqread c_enable_checksums c_verify_checksums_inprogress c_disable_checksums c_wait_checksums_off
-step c_verify_checksums_off: SELECT setting = 'off' FROM pg_catalog.pg_settings WHERE name = 'data_checksums';
-?column?       
-t              
-step r_seqread: SELECT * FROM reader_loop();
-reader_loop    
-t              
-step c_enable_checksums: SELECT pg_enable_data_checksums(1000);
-pg_enable_data_checksums
-step c_verify_checksums_inprogress: SELECT setting = 'inprogress' FROM pg_catalog.pg_settings WHERE name = 'data_checksums';
-?column?       
-t              
-step c_disable_checksums: SELECT pg_disable_data_checksums();
-pg_disable_data_checksums
-step c_wait_checksums_off: SELECT test_checksums_off();
-test_checksums_off
-t              
--- a/src/test/isolation/expected/checksum_enable.out
+++ b/src/test/isolation/expected/checksum_enable.out
-Parsed test spec with 3 sessions
-starting permutation: c_verify_checksums_off w_insert100k r_seqread c_enable_checksums c_wait_for_checksums c_verify_checksums_on
-step c_verify_checksums_off: SELECT setting = 'off' FROM pg_catalog.pg_settings WHERE name = 'data_checksums';
-?column?       
-t              
-step w_insert100k: SELECT insert_1k(100);
-insert_1k      
-t              
-step r_seqread: SELECT * FROM reader_loop();
-reader_loop    
-t              
-step c_enable_checksums: SELECT pg_enable_data_checksums();
-pg_enable_data_checksums
-step c_wait_for_checksums: SELECT test_checksums_on();
-test_checksums_on
-t              
-step c_verify_checksums_on: SELECT setting = 'on' FROM pg_catalog.pg_settings WHERE name = 'data_checksums';
-?column?       
-t              
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -76,7 +76,3 @@ test: predicate-gin
 test: partition-key-update-1
 test: partition-key-update-2
 test: partition-key-update-3
-# The checksum_enable suite will enable checksums for the cluster so should
-# not run before anything expecting the cluster to have checksums turned off
-# test: checksum_cancel
-# test: checksum_enable
--- a/src/test/isolation/specs/checksum_cancel.spec
+++ b/src/test/isolation/specs/checksum_cancel.spec
-setup
-{
-	CREATE TABLE t1 (a serial, b integer, c text);
-	INSERT INTO t1 (b, c) VALUES (generate_series(1,10000), 'starting values');
-	CREATE OR REPLACE FUNCTION test_checksums_off() RETURNS boolean AS $$
-	DECLARE
-		enabled boolean;
-	BEGIN
-		PERFORM pg_sleep(1);
-		SELECT setting = 'off' INTO enabled FROM pg_catalog.pg_settings WHERE name = 'data_checksums';
-		RETURN enabled;
-	END;
-	$$ LANGUAGE plpgsql;
-	CREATE OR REPLACE FUNCTION reader_loop() RETURNS boolean AS $$
-	DECLARE
-		counter integer;
-		enabled boolean;
-	BEGIN
-		FOR counter IN 1..100 LOOP
-			PERFORM count(a) FROM t1;
-		END LOOP;
-		RETURN True;
-	END;
-	$$ LANGUAGE plpgsql;
-}
-teardown
-{
-	DROP FUNCTION reader_loop();
-	DROP FUNCTION test_checksums_off();
-	DROP TABLE t1;
-}
-session "reader"
-step "r_seqread"						{ SELECT * FROM reader_loop(); }
-session "checksums"
-step "c_verify_checksums_off"			{ SELECT setting = 'off' FROM pg_catalog.pg_settings WHERE name = 'data_checksums'; }
-step "c_enable_checksums"				{ SELECT pg_enable_data_checksums(1000); }
-step "c_disable_checksums"				{ SELECT pg_disable_data_checksums(); }
-step "c_verify_checksums_inprogress"	{ SELECT setting = 'inprogress' FROM pg_catalog.pg_settings WHERE name = 'data_checksums'; }
-step "c_wait_checksums_off"				{ SELECT test_checksums_off(); }
-permutation "c_verify_checksums_off" "r_seqread" "c_enable_checksums" "c_verify_checksums_inprogress" "c_disable_checksums" "c_wait_checksums_off"
--- a/src/test/isolation/specs/checksum_enable.spec
+++ b/src/test/isolation/specs/checksum_enable.spec
-setup
-{
-	CREATE TABLE t1 (a serial, b integer, c text);
-	INSERT INTO t1 (b, c) VALUES (generate_series(1,10000), 'starting values');
-	CREATE OR REPLACE FUNCTION insert_1k(iterations int) RETURNS boolean AS $$
-	DECLARE
-		counter integer;
-	BEGIN
-		FOR counter IN 1..$1 LOOP
-			INSERT INTO t1 (b, c) VALUES (
-				generate_series(1, 1000),
-				array_to_string(array(select chr(97 + (random() * 25)::int) from generate_series(1,250)), '')
-			);
-			PERFORM pg_sleep(0.1);
-		END LOOP;
-		RETURN True;
-	END;
-	$$ LANGUAGE plpgsql;
-	CREATE OR REPLACE FUNCTION test_checksums_on() RETURNS boolean AS $$
-	DECLARE
-		enabled boolean;
-	BEGIN
-		LOOP
-			SELECT setting = 'on' INTO enabled FROM pg_catalog.pg_settings WHERE name = 'data_checksums';
-			IF enabled THEN
-				EXIT;
-			END IF;
-			PERFORM pg_sleep(1);
-		END LOOP;
-		RETURN enabled;
-	END;
-	$$ LANGUAGE plpgsql;
-	CREATE OR REPLACE FUNCTION reader_loop() RETURNS boolean AS $$
-	DECLARE
-		counter integer;
-	BEGIN
-		FOR counter IN 1..30 LOOP
-			PERFORM count(a) FROM t1;
-			PERFORM pg_sleep(0.2);
-		END LOOP;
-		RETURN True;
-	END;
-	$$ LANGUAGE plpgsql;
-}
-teardown
-{
-	DROP FUNCTION reader_loop();
-	DROP FUNCTION test_checksums_on();
-	DROP FUNCTION insert_1k(int);
-	DROP TABLE t1;
-}
-session "writer"
-step "w_insert100k"				{ SELECT insert_1k(100); }
-session "reader"
-step "r_seqread"				{ SELECT * FROM reader_loop(); }
-session "checksums"
-step "c_verify_checksums_off"	{ SELECT setting = 'off' FROM pg_catalog.pg_settings WHERE name = 'data_checksums'; }
-step "c_enable_checksums"		{ SELECT pg_enable_data_checksums(); }
-step "c_wait_for_checksums"		{ SELECT test_checksums_on(); }
-step "c_verify_checksums_on"	{ SELECT setting = 'on' FROM pg_catalog.pg_settings WHERE name = 'data_checksums'; }
-permutation "c_verify_checksums_off" "w_insert100k" "r_seqread" "c_enable_checksums" "c_wait_for_checksums" "c_verify_checksums_on"