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 7631cb5c73f8d0d2b747ae83cb116f85210f466f..ee7387873d1044cbb63ef9fe255c90f2c6ba4744 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 a2bd73de9a58cc3a9d14068d3264b56ee8187dce..92c1e66c416c26c78d18c27e3bf810c38d10122a 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))