Fix some more bugs in GIN's WAL replay logic.

In commit 4016bdef8aded77b4903c457050622a5a1815c16 I fixed a bunch of
ginxlog.c bugs having to do with not handling XLogReadBuffer failures
correctly.  However, in ginRedoUpdateMetapage and ginRedoDeleteListPages,
I unaccountably thought that failure to read the metapage would be
impossible and just put in an elog(PANIC) call.  This is of course wrong:
failure is exactly what will happen if the index got dropped (or rebuilt)
between creation of the WAL record and the crash we're trying to recover
from.  I believe this explains Nicholas Wilson's recent report of these
errors getting reached.

Also, fix memory leak in forgetIncompleteSplit.  This wasn't of much
concern when the code was written, but in a long-running standby server
page split records could be expected to accumulate indefinitely.

Back-patch to 8.4 --- before that, GIN didn't have a metapage.

diff --git a/src/backend/access/gin/ginxlog.c b/src/backend/access/gin/ginxlog.c
index fc078b19594929e858c996551b6a992b0489b2fc..327d7c009d67b43410d584fdbc2556bc071980b1 100644 (file)
--- a/src/backend/access/gin/ginxlog.c
+++ b/src/backend/access/gin/ginxlog.c
@@ -59,9 +59,12 @@ forgetIncompleteSplit(RelFileNode node, BlockNumber leftBlkno, BlockNumber updat
        {
                ginIncompleteSplit *split = (ginIncompleteSplit *) lfirst(l);
 
-               if (RelFileNodeEquals(node, split->node) && leftBlkno == split->leftBlkno && updateBlkno == split->rightBlkno)
+               if (RelFileNodeEquals(node, split->node) &&
+                       leftBlkno == split->leftBlkno &&
+                       updateBlkno == split->rightBlkno)
                {
                        incomplete_splits = list_delete_ptr(incomplete_splits, split);
+                       pfree(split);
                        break;
                }
        }
@@ -486,7 +489,7 @@ ginRedoUpdateMetapage(XLogRecPtr lsn, XLogRecord *record)
 
        metabuffer = XLogReadBuffer(data->node, GIN_METAPAGE_BLKNO, false);
        if (!BufferIsValid(metabuffer))
-               elog(PANIC, "GIN metapage disappeared");
+               return;                                 /* assume index was deleted, nothing to do */
        metapage = BufferGetPage(metabuffer);
 
        if (!XLByteLE(lsn, PageGetLSN(metapage)))
@@ -631,7 +634,7 @@ ginRedoDeleteListPages(XLogRecPtr lsn, XLogRecord *record)
 
        metabuffer = XLogReadBuffer(data->node, GIN_METAPAGE_BLKNO, false);
        if (!BufferIsValid(metabuffer))
-               elog(PANIC, "GIN metapage disappeared");
+               return;                                 /* assume index was deleted, nothing to do */
        metapage = BufferGetPage(metabuffer);
 
        if (!XLByteLE(lsn, PageGetLSN(metapage)))