Fix BRIN 32-bit counter wrap issue with huge tables

 A BlockNumber (32-bit) might not be large enough to add bo_pagesPerRange
 to when the table contains close to 2^32 pages.  At worst, this could
 result in a cancellable infinite loop during the BRIN index scan with
 power-of-2 pagesPerRange, and slow (inefficient) BRIN index scans and
 scanning of unneeded heap blocks for non power-of-2 pagesPerRange.
 
 Backpatch to all supported versions.
 
 Author: sunil s <sunilfeb26@gmail.com>
 Reviewed-by: David Rowley <dgrowleyml@gmail.com>
 Reviewed-by: Michael Paquier <michael@paquier.xyz>
 Discussion: https://postgr.es/m/CAOG6S4-tGksTQhVzJM19NzLYAHusXsK2HmADPZzGQcfZABsvpA@mail.gmail.com
 Backpatch-through: 13
 
 

diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 7ff7467e462b0e40623fc33e67a633a23615debc..f37faf3562b4d9c3983152326d8fdda56b380276 100644 (file)
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -573,7 +573,6 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
    Relation    heapRel;
    BrinOpaque *opaque;
    BlockNumber nblocks;
-   BlockNumber heapBlk;
    int64       totalpages = 0;
    FmgrInfo   *consistentFn;
    MemoryContext oldcxt;
@@ -735,9 +734,10 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
    /*
     * Now scan the revmap.  We start by querying for heap page 0,
     * incrementing by the number of pages per range; this gives us a full
-    * view of the table.
+    * view of the table.  We make use of uint64 for heapBlk as a BlockNumber
+    * could wrap for tables with close to 2^32 pages.
     */
-   for (heapBlk = 0; heapBlk < nblocks; heapBlk += opaque->bo_pagesPerRange)
+   for (uint64 heapBlk = 0; heapBlk < nblocks; heapBlk += opaque->bo_pagesPerRange)
    {
        bool        addrange;
        bool        gottuple = false;
@@ -749,7 +749,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
 
        MemoryContextReset(perRangeCxt);
 
-       tup = brinGetTupleForHeapBlock(opaque->bo_rmAccess, heapBlk, &buf,
+       tup = brinGetTupleForHeapBlock(opaque->bo_rmAccess, (BlockNumber ) heapBlk, &buf,
                                       &off, &size, BUFFER_LOCK_SHARE);
        if (tup)
        {
@@ -924,7 +924,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
        /* add the pages in the range to the output bitmap, if needed */
        if (addrange)
        {
-           BlockNumber pageno;
+           uint64 pageno;
 
            for (pageno = heapBlk;
                 pageno <= Min(nblocks, heapBlk + opaque->bo_pagesPerRange) - 1;