Rename nbtree split REDO routine variables.

Make the nbtree page split REDO routine variable names consistent with
_bt_split() (which handles the original execution of page splits).
These names make the code easier to follow by making the distinction
between the original page and the left half of the split clear.  (The
left half of the split page is a temp page that REDO creates to replace
the origpage contents.)

Also reduce the elevel used when adding a new high key to the temp page
from PANIC to ERROR to be consistent.  We already only raise an ERROR
when data item PageAddItem() temp page calls fail.

diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c
index be0fa450f31da09488888a4b6ffe25b53b57c760..1fd6392463286f912ffcb34202d23940ee7f884a 100644 (file)
--- a/src/backend/access/nbtree/nbtxlog.c
+++ b/src/backend/access/nbtree/nbtxlog.c
@@ -256,20 +256,20 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
    XLogRecPtr  lsn = record->EndRecPtr;
    xl_btree_split *xlrec = (xl_btree_split *) XLogRecGetData(record);
    bool        isleaf = (xlrec->level == 0);
-   Buffer      lbuf;
+   Buffer      buf;
    Buffer      rbuf;
    Page        rpage;
    BTPageOpaque ropaque;
    char       *datapos;
    Size        datalen;
-   BlockNumber leftsib;
-   BlockNumber rightsib;
-   BlockNumber rnext;
+   BlockNumber origpagenumber;
+   BlockNumber rightpagenumber;
+   BlockNumber spagenumber;
 
-   XLogRecGetBlockTag(record, 0, NULL, NULL, &leftsib);
-   XLogRecGetBlockTag(record, 1, NULL, NULL, &rightsib);
-   if (!XLogRecGetBlockTag(record, 2, NULL, NULL, &rnext))
-       rnext = P_NONE;
+   XLogRecGetBlockTag(record, 0, NULL, NULL, &origpagenumber);
+   XLogRecGetBlockTag(record, 1, NULL, NULL, &rightpagenumber);
+   if (!XLogRecGetBlockTag(record, 2, NULL, NULL, &spagenumber))
+       spagenumber = P_NONE;
 
    /*
     * Clear the incomplete split flag on the left sibling of the child page
@@ -287,8 +287,8 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
    _bt_pageinit(rpage, BufferGetPageSize(rbuf));
    ropaque = (BTPageOpaque) PageGetSpecialPointer(rpage);
 
-   ropaque->btpo_prev = leftsib;
-   ropaque->btpo_next = rnext;
+   ropaque->btpo_prev = origpagenumber;
+   ropaque->btpo_next = spagenumber;
    ropaque->btpo.level = xlrec->level;
    ropaque->btpo_flags = isleaf ? BTP_LEAF : 0;
    ropaque->btpo_cycleid = 0;
@@ -298,8 +298,8 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
    PageSetLSN(rpage, lsn);
    MarkBufferDirty(rbuf);
 
-   /* Now reconstruct left (original) sibling page */
-   if (XLogReadBufferForRedo(record, 0, &lbuf) == BLK_NEEDS_REDO)
+   /* Now reconstruct original page (left half of split) */
+   if (XLogReadBufferForRedo(record, 0, &buf) == BLK_NEEDS_REDO)
    {
        /*
         * To retain the same physical order of the tuples that they had, we
@@ -309,15 +309,15 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
         * checking possible.  See also _bt_restore_page(), which does the
         * same for the right page.
         */
-       Page        lpage = (Page) BufferGetPage(lbuf);
-       BTPageOpaque lopaque = (BTPageOpaque) PageGetSpecialPointer(lpage);
+       Page        origpage = (Page) BufferGetPage(buf);
+       BTPageOpaque oopaque = (BTPageOpaque) PageGetSpecialPointer(origpage);
        OffsetNumber off;
        IndexTuple  newitem = NULL,
                    left_hikey = NULL,
                    nposting = NULL;
        Size        newitemsz = 0,
                    left_hikeysz = 0;
-       Page        newlpage;
+       Page        leftpage;
        OffsetNumber leftoff,
                    replacepostingoff = InvalidOffsetNumber;
 
@@ -340,8 +340,8 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
 
                /* Use mutable, aligned newitem copy in _bt_swap_posting() */
                newitem = CopyIndexTuple(newitem);
-               itemid = PageGetItemId(lpage, replacepostingoff);
-               oposting = (IndexTuple) PageGetItem(lpage, itemid);
+               itemid = PageGetItemId(origpage, replacepostingoff);
+               oposting = (IndexTuple) PageGetItem(origpage, itemid);
                nposting = _bt_swap_posting(newitem, oposting,
                                            xlrec->postingoff);
            }
@@ -359,16 +359,16 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
 
        Assert(datalen == 0);
 
-       newlpage = PageGetTempPageCopySpecial(lpage);
+       leftpage = PageGetTempPageCopySpecial(origpage);
 
-       /* Set high key */
+       /* Add high key tuple from WAL record to temp page */
        leftoff = P_HIKEY;
-       if (PageAddItem(newlpage, (Item) left_hikey, left_hikeysz,
-                       P_HIKEY, false, false) == InvalidOffsetNumber)
-           elog(PANIC, "failed to add high key to left page after split");
+       if (PageAddItem(leftpage, (Item) left_hikey, left_hikeysz, P_HIKEY,
+                       false, false) == InvalidOffsetNumber)
+           elog(ERROR, "failed to add high key to left page after split");
        leftoff = OffsetNumberNext(leftoff);
 
-       for (off = P_FIRSTDATAKEY(lopaque); off < xlrec->firstrightoff; off++)
+       for (off = P_FIRSTDATAKEY(oopaque); off < xlrec->firstrightoff; off++)
        {
            ItemId      itemid;
            Size        itemsz;
@@ -379,7 +379,7 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
            {
                Assert(newitemonleft ||
                       xlrec->firstrightoff == xlrec->newitemoff);
-               if (PageAddItem(newlpage, (Item) nposting,
+               if (PageAddItem(leftpage, (Item) nposting,
                                MAXALIGN(IndexTupleSize(nposting)), leftoff,
                                false, false) == InvalidOffsetNumber)
                    elog(ERROR, "failed to add new posting list item to left page after split");
@@ -390,16 +390,16 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
            /* add the new item if it was inserted on left page */
            else if (newitemonleft && off == xlrec->newitemoff)
            {
-               if (PageAddItem(newlpage, (Item) newitem, newitemsz, leftoff,
+               if (PageAddItem(leftpage, (Item) newitem, newitemsz, leftoff,
                                false, false) == InvalidOffsetNumber)
                    elog(ERROR, "failed to add new item to left page after split");
                leftoff = OffsetNumberNext(leftoff);
            }
 
-           itemid = PageGetItemId(lpage, off);
+           itemid = PageGetItemId(origpage, off);
            itemsz = ItemIdGetLength(itemid);
-           item = (IndexTuple) PageGetItem(lpage, itemid);
-           if (PageAddItem(newlpage, (Item) item, itemsz, leftoff,
+           item = (IndexTuple) PageGetItem(origpage, itemid);
+           if (PageAddItem(leftpage, (Item) item, itemsz, leftoff,
                            false, false) == InvalidOffsetNumber)
                elog(ERROR, "failed to add old item to left page after split");
            leftoff = OffsetNumberNext(leftoff);
@@ -408,31 +408,31 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
        /* cope with possibility that newitem goes at the end */
        if (newitemonleft && off == xlrec->newitemoff)
        {
-           if (PageAddItem(newlpage, (Item) newitem, newitemsz, leftoff,
+           if (PageAddItem(leftpage, (Item) newitem, newitemsz, leftoff,
                            false, false) == InvalidOffsetNumber)
                elog(ERROR, "failed to add new item to left page after split");
            leftoff = OffsetNumberNext(leftoff);
        }
 
-       PageRestoreTempPage(newlpage, lpage);
+       PageRestoreTempPage(leftpage, origpage);
 
        /* Fix opaque fields */
-       lopaque->btpo_flags = BTP_INCOMPLETE_SPLIT;
+       oopaque->btpo_flags = BTP_INCOMPLETE_SPLIT;
        if (isleaf)
-           lopaque->btpo_flags |= BTP_LEAF;
-       lopaque->btpo_next = rightsib;
-       lopaque->btpo_cycleid = 0;
+           oopaque->btpo_flags |= BTP_LEAF;
+       oopaque->btpo_next = rightpagenumber;
+       oopaque->btpo_cycleid = 0;
 
-       PageSetLSN(lpage, lsn);
-       MarkBufferDirty(lbuf);
+       PageSetLSN(origpage, lsn);
+       MarkBufferDirty(buf);
    }
 
    /*
     * We no longer need the buffers.  They must be released together, so that
     * readers cannot observe two inconsistent halves.
     */
-   if (BufferIsValid(lbuf))
-       UnlockReleaseBuffer(lbuf);
+   if (BufferIsValid(buf))
+       UnlockReleaseBuffer(buf);
    UnlockReleaseBuffer(rbuf);
 
    /*
@@ -443,22 +443,22 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
     * replay, because no other index update can be in progress, and readers
     * will cope properly when following an obsolete left-link.
     */
-   if (rnext != P_NONE)
+   if (spagenumber != P_NONE)
    {
-       Buffer      buffer;
+       Buffer      sbuf;
 
-       if (XLogReadBufferForRedo(record, 2, &buffer) == BLK_NEEDS_REDO)
+       if (XLogReadBufferForRedo(record, 2, &sbuf) == BLK_NEEDS_REDO)
        {
-           Page        page = (Page) BufferGetPage(buffer);
-           BTPageOpaque pageop = (BTPageOpaque) PageGetSpecialPointer(page);
+           Page        spage = (Page) BufferGetPage(sbuf);
+           BTPageOpaque spageop = (BTPageOpaque) PageGetSpecialPointer(spage);
 
-           pageop->btpo_prev = rightsib;
+           spageop->btpo_prev = rightpagenumber;
 
-           PageSetLSN(page, lsn);
-           MarkBufferDirty(buffer);
+           PageSetLSN(spage, lsn);
+           MarkBufferDirty(sbuf);
        }
-       if (BufferIsValid(buffer))
-           UnlockReleaseBuffer(buffer);
+       if (BufferIsValid(sbuf))
+           UnlockReleaseBuffer(sbuf);
    }
 }