Revert recovery prefetching feature.

This set of commits has some bugs with known fixes, but at this late
stage in the release cycle it seems best to revert and resubmit next
time, along with some new automated test coverage for this whole area.

Commits reverted:

dc88460c: Doc: Review for "Optionally prefetch referenced data in recovery."
1d257577: Optionally prefetch referenced data in recovery.
f003d9f8: Add circular WAL decoding buffer.
323cbe7c: Remove read_page callback from XLogReader.

Remove the new GUC group WAL_RECOVERY recently added by a55a9847, as the
corresponding section of config.sgml is now reverted.

Discussion: https://postgr.es/m/CAOuzzgrn7iKnFRsB4MHp3UisEQAGgZMbk_ViTN4HV4-Ksq8zCg%40mail.gmail.com

1 files changed, 1 insertions, 102 deletions

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index ba335fd3429..e94f5f55c78 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -38,7 +38,6 @@
 #include "access/transam.h"
 #include "access/twophase_rmgr.h"
 #include "access/xact.h"
-#include "access/xlogprefetch.h"
 #include "catalog/partition.h"
 #include "catalog/pg_database.h"
 #include "catalog/pg_proc.h"
@@ -280,7 +279,6 @@ static PgStat_GlobalStats globalStats;
 static PgStat_WalStats walStats;
 static PgStat_SLRUStats slruStats[SLRU_NUM_ELEMENTS];
 static HTAB *replSlotStatHash = NULL;
-static PgStat_RecoveryPrefetchStats recoveryPrefetchStats;
 
 /*
  * List of OIDs of databases we need to write out.  If an entry is InvalidOid,
@@ -352,7 +350,6 @@ static void pgstat_recv_archiver(PgStat_MsgArchiver *msg, int len);
 static void pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len);
 static void pgstat_recv_wal(PgStat_MsgWal *msg, int len);
 static void pgstat_recv_slru(PgStat_MsgSLRU *msg, int len);
-static void pgstat_recv_recoveryprefetch(PgStat_MsgRecoveryPrefetch *msg, int len);
 static void pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len);
 static void pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len);
 static void pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len);
@@ -1446,20 +1443,11 @@ pgstat_reset_shared_counters(const char *target)
 		msg.m_resettarget = RESET_BGWRITER;
 	else if (strcmp(target, "wal") == 0)
 		msg.m_resettarget = RESET_WAL;
-	else if (strcmp(target, "prefetch_recovery") == 0)
-	{
-		/*
-		 * We can't ask the stats collector to do this for us as it is not
-		 * attached to shared memory.
-		 */
-		XLogPrefetchRequestResetStats();
-		return;
-	}
 	else
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 				 errmsg("unrecognized reset target: \"%s\"", target),
-				 errhint("Target must be \"archiver\", \"bgwriter\", \"wal\" or \"prefetch_recovery\".")));
+				 errhint("Target must be \"archiver\", \"bgwriter\" or \"wal\".")));
 
 	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETSHAREDCOUNTER);
 	pgstat_send(&msg, sizeof(msg));
@@ -2898,22 +2886,6 @@ pgstat_fetch_replslot(NameData slotname)
 }
 
 /*
- * ---------
- * pgstat_fetch_recoveryprefetch() -
- *
- *	Support function for restoring the counters managed by xlogprefetch.c.
- * ---------
- */
-PgStat_RecoveryPrefetchStats *
-pgstat_fetch_recoveryprefetch(void)
-{
-	backend_read_statsfile();
-
-	return &recoveryPrefetchStats;
-}
-
-
-/*
  * Shut down a single backend's statistics reporting at process exit.
  *
  * Flush any remaining statistics counts out to the collector.
@@ -3189,23 +3161,6 @@ pgstat_send_slru(void)
 
 
 /* ----------
- * pgstat_send_recoveryprefetch() -
- *
- *		Send recovery prefetch statistics to the collector
- * ----------
- */
-void
-pgstat_send_recoveryprefetch(PgStat_RecoveryPrefetchStats *stats)
-{
-	PgStat_MsgRecoveryPrefetch msg;
-
-	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RECOVERYPREFETCH);
-	msg.m_stats = *stats;
-	pgstat_send(&msg, sizeof(msg));
-}
-
-
-/* ----------
  * PgstatCollectorMain() -
  *
  *	Start up the statistics collector process.  This is the body of the
@@ -3422,10 +3377,6 @@ PgstatCollectorMain(int argc, char *argv[])
 					pgstat_recv_slru(&msg.msg_slru, len);
 					break;
 
-				case PGSTAT_MTYPE_RECOVERYPREFETCH:
-					pgstat_recv_recoveryprefetch(&msg.msg_recoveryprefetch, len);
-					break;
-
 				case PGSTAT_MTYPE_FUNCSTAT:
 					pgstat_recv_funcstat(&msg.msg_funcstat, len);
 					break;
@@ -3719,13 +3670,6 @@ pgstat_write_statsfiles(bool permanent, bool allDbs)
 	(void) rc;					/* we'll check for error with ferror */
 
 	/*
-	 * Write recovery prefetch stats struct
-	 */
-	rc = fwrite(&recoveryPrefetchStats, sizeof(recoveryPrefetchStats), 1,
-				fpout);
-	(void) rc;					/* we'll check for error with ferror */
-
-	/*
 	 * Walk through the database table.
 	 */
 	hash_seq_init(&hstat, pgStatDBHash);
@@ -4000,7 +3944,6 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep)
 	memset(&archiverStats, 0, sizeof(archiverStats));
 	memset(&walStats, 0, sizeof(walStats));
 	memset(&slruStats, 0, sizeof(slruStats));
-	memset(&recoveryPrefetchStats, 0, sizeof(recoveryPrefetchStats));
 
 	/*
 	 * Set the current timestamp (will be kept only in case we can't load an
@@ -4101,18 +4044,6 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep)
 	}
 
 	/*
-	 * Read recoveryPrefetchStats struct
-	 */
-	if (fread(&recoveryPrefetchStats, 1, sizeof(recoveryPrefetchStats),
-			  fpin) != sizeof(recoveryPrefetchStats))
-	{
-		ereport(pgStatRunningInCollector ? LOG : WARNING,
-				(errmsg("corrupted statistics file \"%s\"", statfile)));
-		memset(&recoveryPrefetchStats, 0, sizeof(recoveryPrefetchStats));
-		goto done;
-	}
-
-	/*
 	 * We found an existing collector stats file. Read it and put all the
 	 * hashtable entries into place.
 	 */
@@ -4452,7 +4383,6 @@ pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent,
 	PgStat_WalStats myWalStats;
 	PgStat_SLRUStats mySLRUStats[SLRU_NUM_ELEMENTS];
 	PgStat_StatReplSlotEntry myReplSlotStats;
-	PgStat_RecoveryPrefetchStats myRecoveryPrefetchStats;
 	FILE	   *fpin;
 	int32		format_id;
 	const char *statfile = permanent ? PGSTAT_STAT_PERMANENT_FILENAME : pgstat_stat_filename;
@@ -4529,18 +4459,6 @@ pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent,
 		return false;
 	}
 
-	/*
-	 * Read recovery prefetch stats struct
-	 */
-	if (fread(&myRecoveryPrefetchStats, 1, sizeof(myRecoveryPrefetchStats),
-			  fpin) != sizeof(myRecoveryPrefetchStats))
-	{
-		ereport(pgStatRunningInCollector ? LOG : WARNING,
-				(errmsg("corrupted statistics file \"%s\"", statfile)));
-		FreeFile(fpin);
-		return false;
-	}
-
 	/* By default, we're going to return the timestamp of the global file. */
 	*ts = myGlobalStats.stats_timestamp;
 
@@ -4724,13 +4642,6 @@ backend_read_statsfile(void)
 		if (ok && file_ts >= min_ts)
 			break;
 
-		/*
-		 * If we're in crash recovery, the collector may not even be running,
-		 * so work with what we have.
-		 */
-		if (InRecovery)
-			break;
-
 		/* Not there or too old, so kick the collector and wait a bit */
 		if ((count % PGSTAT_INQ_LOOP_COUNT) == 0)
 			pgstat_send_inquiry(cur_ts, min_ts, inquiry_db);
@@ -5471,18 +5382,6 @@ pgstat_recv_slru(PgStat_MsgSLRU *msg, int len)
 }
 
 /* ----------
- * pgstat_recv_recoveryprefetch() -
- *
- *	Process a recovery prefetch message.
- * ----------
- */
-static void
-pgstat_recv_recoveryprefetch(PgStat_MsgRecoveryPrefetch *msg, int len)
-{
-	recoveryPrefetchStats = msg->m_stats;
-}
-
-/* ----------
  * pgstat_recv_recoveryconflict() -
  *
  *	Process a RECOVERYCONFLICT message.