From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Thu, 6 Nov 2014 12:40:04 +0000 (+0200)
Subject: Add XLR_SPECIAL_REL_UPDATES flag
X-Git-Url: http://git.postgresql.org/gitweb/review?a=commitdiff_plain;h=f59201d2966f62108682fe31bbdd5a0ab77e5354;p=users%2Fheikki%2Fpostgres.git

Add XLR_SPECIAL_REL_UPDATES flag
---

diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
index bde40df27f..efc161ba9d 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -339,8 +339,11 @@ XLogInsert(RmgrId rmid, uint8 info)
 	if (!begininsert_called)
 		elog(ERROR, "XLogBeginInsert was not called");
 
-	/* info's high bits are reserved for use by me */
-	if (info & XLR_INFO_MASK)
+	/*
+	 * The caller can set rmgr bits and XLR_SPECIAL_REL_UPDATE; the rest
+	 * are reserved for use by me.
+	 */
+	if ((info & ~(XLR_RMGR_INFO_MASK | XLR_SPECIAL_REL_UPDATE)) != 0)
 		elog(PANIC, "invalid xlog info mask %02X", info);
 
 	TRACE_POSTGRESQL_XLOG_INSERT(rmid, info);
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index 2c6b5f2758..19b97644b8 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -134,7 +134,7 @@ log_smgrcreate(RelFileNode *rnode, ForkNumber forkNum)
 
 	XLogBeginInsert();
 	XLogRegisterData((char *) &xlrec, sizeof(xlrec));
-	XLogInsert(RM_SMGR_ID, XLOG_SMGR_CREATE);
+	XLogInsert(RM_SMGR_ID, XLOG_SMGR_CREATE | XLR_SPECIAL_REL_UPDATE);
 }
 
 /*
@@ -272,7 +272,8 @@ RelationTruncate(Relation rel, BlockNumber nblocks)
 		XLogBeginInsert();
 		XLogRegisterData((char *) &xlrec, sizeof(xlrec));
 
-		lsn = XLogInsert(RM_SMGR_ID, XLOG_SMGR_TRUNCATE);
+		lsn = XLogInsert(RM_SMGR_ID,
+						 XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE);
 
 		/*
 		 * Flush, because otherwise the truncation of the main relation might
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 4546bebf28..8fe12f737d 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -629,7 +629,8 @@ createdb(const CreatedbStmt *stmt)
 				XLogRegisterData((char *) &xlrec,
 									 sizeof(xl_dbase_create_rec));
 
-				(void) XLogInsert(RM_DBASE_ID, XLOG_DBASE_CREATE);
+				(void) XLogInsert(RM_DBASE_ID,
+								  XLOG_DBASE_CREATE | XLR_SPECIAL_REL_UPDATE);
 			}
 		}
 		heap_endscan(scan);
@@ -1233,7 +1234,8 @@ movedb(const char *dbname, const char *tblspcname)
 			XLogBeginInsert();
 			XLogRegisterData((char *) &xlrec, sizeof(xl_dbase_create_rec));
 
-			(void) XLogInsert(RM_DBASE_ID, XLOG_DBASE_CREATE);
+			(void) XLogInsert(RM_DBASE_ID,
+							  XLOG_DBASE_CREATE | XLR_SPECIAL_REL_UPDATE);
 		}
 
 		/*
@@ -1332,7 +1334,8 @@ movedb(const char *dbname, const char *tblspcname)
 		XLogBeginInsert();
 		XLogRegisterData((char *) &xlrec, sizeof(xl_dbase_drop_rec));
 
-		(void) XLogInsert(RM_DBASE_ID, XLOG_DBASE_DROP);
+		(void) XLogInsert(RM_DBASE_ID,
+						  XLOG_DBASE_DROP | XLR_SPECIAL_REL_UPDATE);
 	}
 
 	/* Now it's safe to release the database lock */
@@ -1869,7 +1872,8 @@ remove_dbtablespaces(Oid db_id)
 			XLogBeginInsert();
 			XLogRegisterData((char *) &xlrec, sizeof(xl_dbase_drop_rec));
 
-			(void) XLogInsert(RM_DBASE_ID, XLOG_DBASE_DROP);
+			(void) XLogInsert(RM_DBASE_ID,
+							  XLOG_DBASE_DROP | XLR_SPECIAL_REL_UPDATE);
 		}
 
 		pfree(dstpath);
diff --git a/src/include/access/xlogrecord.h b/src/include/access/xlogrecord.h
index b1e0421419..ba00b4eaba 100644
--- a/src/include/access/xlogrecord.h
+++ b/src/include/access/xlogrecord.h
@@ -58,17 +58,28 @@ typedef struct XLogRecord
 #define SizeOfXLogRecord	MAXALIGN(sizeof(XLogRecord))
 
 /*
- * XLOG uses only low 4 bits of xl_info.  High 4 bits may be used by rmgr.
+ * The high 4 bits in xl_info may be used freely by rmgr. The
+ * XLR_SPECIAL_REL_UPDATE bit can be passed by XLogInsert caller. The rest
+ * are set internally by XLogInsert.
  */
 #define XLR_INFO_MASK			0x0F
 #define XLR_RMGR_INFO_MASK		0xF0
 
+/*
+ * If a WAL record modifies any relation files, in ways not covered by the
+ * usual block references, this flag is set. This is not used for anything
+ * by PostgreSQL itself, but it allows external tools that read WAL and keep
+ * track of modified blocks to recognize such special record types.
+ */
+#define XLR_SPECIAL_REL_UPDATE	0x01
+
 /*
  * xl_len == 0 is only allowed if this flag is set. This provides an extra
  * cross-check when reading records.
  */
 #define XLR_NO_RMGR_DATA		0x02
 
+
 /*
  * Header info for block data appended to an XLOG record.
  *