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 d3b5f349a24ac738c5f75f644c07a55b20dc0ec0..9f8838ffa03f15e567845f66d28e80afa6e63a75 100644 (file)
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -360,7 +360,6 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
        Relation        heapRel;
        BrinOpaque *opaque;
        BlockNumber nblocks;
-       BlockNumber heapBlk;
        int64           totalpages = 0;
        FmgrInfo   *consistentFn;
        MemoryContext oldcxt;
@@ -521,9 +520,10 @@ 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;
@@ -535,7 +535,7 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
 
                MemoryContextResetAndDeleteChildren(perRangeCxt);
 
-               tup = brinGetTupleForHeapBlock(opaque->bo_rmAccess, heapBlk, &buf,
+               tup = brinGetTupleForHeapBlock(opaque->bo_rmAccess, (BlockNumber ) heapBlk, &buf,
                                                                           &off, &size, BUFFER_LOCK_SHARE,
                                                                           scan->xs_snapshot);
                if (tup)
@@ -711,7 +711,7 @@ 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;