BRIN: fix bug in xlog backup block counting

The code that generates the BRIN_XLOG_UPDATE removes the buffer
reference when the page that's target for the updated tuple is freshly
initialized.  This is a pretty usual optimization, but was breaking the
case where the revmap buffer, which is referenced in the same WAL
record, is getting a backup block: the replay code was using backup
block index 1, which is not valid when the update target buffer gets
pruned; the revmap buffer gets assigned 0 instead.  Make sure to use the
correct backup block index for revmap when replaying.

Bug reported by Fujii Masao.

diff --git a/src/backend/access/brin/brin_xlog.c b/src/backend/access/brin/brin_xlog.c
index ebef984e7f161e7870fa3d31d841f631da12abb9..29370689a704b2ea5ec1cf82bd93d0a92ee6f33b 100644 (file)
--- a/src/backend/access/brin/brin_xlog.c
+++ b/src/backend/access/brin/brin_xlog.c
@@ -60,9 +60,11 @@ brin_xlog_insert_update(XLogRecPtr lsn, XLogRecord *record,
     */
    if (record->xl_info & XLOG_BRIN_INIT_PAGE)
    {
-       XLogReadBufferForRedoExtended(lsn, record, 0,
-                                     xlrec->node, MAIN_FORKNUM, blkno,
-                                     RBM_ZERO, false, &buffer);
+       /*
+        * No full-page image here.  Don't try to read it, because there
+        * might be one for the revmap buffer, below.
+        */
+       buffer = XLogReadBuffer(xlrec->node, blkno, true);
        page = BufferGetPage(buffer);
        brin_page_init(page, BRIN_PAGETYPE_REGULAR);
        action = BLK_NEEDS_REDO;
@@ -97,7 +99,9 @@ brin_xlog_insert_update(XLogRecPtr lsn, XLogRecord *record,
        UnlockReleaseBuffer(buffer);
 
    /* update the revmap */
-   action = XLogReadBufferForRedo(lsn, record, 1, xlrec->node,
+   action = XLogReadBufferForRedo(lsn, record,
+                                  record->xl_info & XLOG_BRIN_INIT_PAGE ? 0 : 1,
+                                  xlrec->node,
                                   xlrec->revmapBlk, &buffer);
    if (action == BLK_NEEDS_REDO)
    {