From b3327cace3bebdb15006834e21672fc30cb2f0bb Mon Sep 17 00:00:00 2001 From: Matthias van de Meent Date: Fri, 20 Nov 2020 16:23:59 +0100 Subject: [PATCH v2] Fix CLUSTER progress reporting of number of blocks scanned. The heapScan need not start at block 0, so heapScan->rs_cblock need not be the correct value for amount of blocks scanned. A more correct value is ((heapScan->rs_cblock - heapScan->rs_startblock + heapScan->rs_nblocks) % heapScan->rs_nblocks), as it accounts for the wraparound and the initial offset of the heapScan. Additionally, a heap scan need not return tuples from the last scanned page. This means that when table_scan_getnextslot returns false, we must manually update the heap_blks_scanned parameter to the number of blocks in the heap scan. --- src/backend/access/heap/heapam_handler.c | 28 ++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index dcaea7135f..f20d4bed07 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -698,6 +698,7 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, Datum *values; bool *isnull; BufferHeapTupleTableSlot *hslot; + BlockNumber prev_cblock = InvalidBlockNumber; /* Remember if it's a system catalog */ is_system_catalog = IsSystemRelation(OldHeap); @@ -793,14 +794,37 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap, else { if (!table_scan_getnextslot(tableScan, ForwardScanDirection, slot)) + { + /* + * A heap scan need not return tuples for the last page it has + * scanned. To ensure that heap_blks_scanned is equivalent to + * total_heap_blks after the table scan phase, this parameter + * is manually updated to the correct value when the table scan + * finishes. + */ + pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_BLKS_SCANNED, + heapScan->rs_nblocks); break; + } /* * In scan-and-sort mode and also VACUUM FULL, set heap blocks * scanned + * + * Note that heapScan may start at an offset and wrap around, i.e. + * rs_startblock may be >0, and rs_cblock may end with a number + * below rs_startblock. To prevent showing this wraparound to the + * user, we offset rs_cblock by rs_startblock (modulo rs_nblocks). */ - pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_BLKS_SCANNED, - heapScan->rs_cblock + 1); + if (prev_cblock != heapScan->rs_cblock) + { + pgstat_progress_update_param(PROGRESS_CLUSTER_HEAP_BLKS_SCANNED, + (heapScan->rs_cblock + + heapScan->rs_nblocks - + heapScan->rs_startblock + ) % heapScan->rs_nblocks + 1); + prev_cblock = heapScan->rs_cblock; + } } tuple = ExecFetchSlotHeapTuple(slot, false, NULL); -- 2.20.1