Fix nbtree page split rmgr desc routine.

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 2c03216d831, 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
index a713d7f222b1b46ab3cad9760f609a682b9d16e1..66ed163b9784d109407230d1c352552cc33f1a1f 100644 (file)
--- 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/nbtree.h b/src/include/access/nbtree.h
index d8c14e0493ad4754c6873c428ae62e481f5ca0b1..f272eea37a9a11673f6dc7c135fade8abf2e7036 100644 (file)
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -265,11 +265,11 @@ 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
  *
@@ -291,7 +291,7 @@ 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))