Fix nbtree page split rmgr desc routine.

petergeoghegan · petergeoghegan · commit 09b236af90be · 2019-09-12T15:45:03.000-07:00
Include newitemoff in rmgr desc output for nbtree page split records. In passing, correct an obsolete comment that claimed that newitemoff is only logged for _L variant nbtree page split WAL records. Both issues were oversights in commit 2c03216, which revamped the WAL format. Author: Peter Geoghegan Backpatch: 9.5-, where the WAL format was revamped.
diff --git a/src/backend/access/rmgrdesc/nbtdesc.c b/src/backend/access/rmgrdesc/nbtdesc.c
@@ -40,8 +40,8 @@ btree_desc(StringInfo buf, XLogReaderState *record)
 			{
 				xl_btree_split *xlrec = (xl_btree_split *) rec;
 
-				appendStringInfo(buf, "level %u, firstright %d",
-								 xlrec->level, xlrec->firstright);
+				appendStringInfo(buf, "level %u, firstright %d, newitemoff %d",
+								 xlrec->level, xlrec->firstright, xlrec->newitemoff);
 				break;
 			}
 		case XLOG_BTREE_VACUUM:
diff --git a/src/include/access/nbtxlog.h b/src/include/access/nbtxlog.h
@@ -78,11 +78,11 @@ typedef struct xl_btree_insert
  *
  * Note: the four XLOG_BTREE_SPLIT xl_info codes all use this data record.
  * The _L and _R variants indicate whether the inserted tuple went into the
- * left or right split page (and thus, whether newitemoff and the new item
- * are stored or not).  The _ROOT variants indicate that we are splitting
- * the root page, and thus that a newroot record rather than an insert or
- * split record should follow.  Note that a split record never carries a
- * metapage update --- we'll do that in the parent-level update.
+ * left or right split page (and thus, whether the new item is stored or not).
+ * The _ROOT variants indicate that we are splitting the root page, and thus
+ * that a newroot record rather than an insert or split record should follow.
+ * Note that a split record never carries a metapage update --- we'll do that
+ * in the parent-level update.
  *
  * Backup Blk 0: original page / new left page
  *
@@ -104,7 +104,7 @@ typedef struct xl_btree_split
 {
 	uint32		level;			/* tree level of page being split */
 	OffsetNumber firstright;	/* first item moved to right page */
-	OffsetNumber newitemoff;	/* new item's offset (if placed on left page) */
+	OffsetNumber newitemoff;	/* new item's offset (useful for _L variants) */
 } xl_btree_split;
 
 #define SizeOfBtreeSplit	(offsetof(xl_btree_split, newitemoff) + sizeof(OffsetNumber))

Original file line number	Diff line number	Diff line change
`@@ -40,8 +40,8 @@ btree_desc(StringInfo buf, XLogReaderState *record)`
`40`	`40`	`{`
`41`	`41`	`xl_btree_split xlrec = (xl_btree_split ) rec;`
`42`	`42`
`43`		`- appendStringInfo(buf, "level %u, firstright %d",`
`44`		`- xlrec->level, xlrec->firstright);`
	`43`	`+ appendStringInfo(buf, "level %u, firstright %d, newitemoff %d",`
	`44`	`+ xlrec->level, xlrec->firstright, xlrec->newitemoff);`
`45`	`45`	`break;`
`46`	`46`	`}`
`47`	`47`	`case XLOG_BTREE_VACUUM:`
Original file line number	Diff line number	Diff line change
`@@ -78,11 +78,11 @@ typedef struct xl_btree_insert`
`78`	`78`	`*`
`79`	`79`	`* Note: the four XLOG_BTREE_SPLIT xl_info codes all use this data record.`
`80`	`80`	`* The _L and _R variants indicate whether the inserted tuple went into the`
`81`		`- * left or right split page (and thus, whether newitemoff and the new item`
`82`		`- * are stored or not). The _ROOT variants indicate that we are splitting`
`83`		`- * the root page, and thus that a newroot record rather than an insert or`
`84`		`- * split record should follow. Note that a split record never carries a`
`85`		`- * metapage update --- we'll do that in the parent-level update.`
	`81`	`+ * left or right split page (and thus, whether the new item is stored or not).`
	`82`	`+ * The _ROOT variants indicate that we are splitting the root page, and thus`
	`83`	`+ * that a newroot record rather than an insert or split record should follow.`
	`84`	`+ * Note that a split record never carries a metapage update --- we'll do that`
	`85`	`+ * in the parent-level update.`
`86`	`86`	`*`
`87`	`87`	`* Backup Blk 0: original page / new left page`
`88`	`88`	`*`
`@@ -104,7 +104,7 @@ typedef struct xl_btree_split`
`104`	`104`	`{`
`105`	`105`	`uint32 level; /* tree level of page being split */`
`106`	`106`	`OffsetNumber firstright; /* first item moved to right page */`
`107`		`- OffsetNumber newitemoff; /* new item's offset (if placed on left page) */`
	`107`	`+ OffsetNumber newitemoff; /* new item's offset (useful for _L variants) */`
`108`	`108`	`} xl_btree_split;`
`109`	`109`
`110`	`110`	`#define SizeOfBtreeSplit (offsetof(xl_btree_split, newitemoff) + sizeof(OffsetNumber))`