From 90525d7b4e0fe5ebd53960cd7ef59ee11ff06516 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Tue, 15 Jan 2019 12:19:21 -0800 Subject: [PATCH] Don't duplicate parallel seqscan shmem sizing logic in nbtree. This is architecturally mildly problematic, which becomes more pronounced with the upcoming introduction of pluggable storage. To fix, teach heap_parallelscan_estimate() to deal with SnapshotAny snapshots, and then use it from _bt_parallel_estimate_shared(). Author: Andres Freund Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de --- src/backend/access/heap/heapam.c | 10 ++++++++-- src/backend/access/nbtree/nbtsort.c | 13 +++---------- 2 files changed, 11 insertions(+), 12 deletions(-) diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index f7b08ffdd1..9afbc8228d 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1615,8 +1615,14 @@ heap_endscan(HeapScanDesc scan) Size heap_parallelscan_estimate(Snapshot snapshot) { - return add_size(offsetof(ParallelHeapScanDescData, phs_snapshot_data), - EstimateSnapshotSpace(snapshot)); + Size sz = offsetof(ParallelHeapScanDescData, phs_snapshot_data); + + if (IsMVCCSnapshot(snapshot)) + sz = add_size(sz, EstimateSnapshotSpace(snapshot)); + else + Assert(snapshot == SnapshotAny); + + return sz; } /* ---------------- diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c index 83966dc4d4..5cc3cf57e2 100644 --- a/src/backend/access/nbtree/nbtsort.c +++ b/src/backend/access/nbtree/nbtsort.c @@ -158,7 +158,7 @@ typedef struct BTShared /* * This variable-sized field must come last. * - * See _bt_parallel_estimate_shared(). + * See _bt_parallel_estimate_shared() and heap_parallelscan_estimate(). */ ParallelHeapScanDescData heapdesc; } BTShared; @@ -1405,15 +1405,8 @@ _bt_end_parallel(BTLeader *btleader) static Size _bt_parallel_estimate_shared(Snapshot snapshot) { - if (!IsMVCCSnapshot(snapshot)) - { - Assert(snapshot == SnapshotAny); - return sizeof(BTShared); - } - - return add_size(offsetof(BTShared, heapdesc) + - offsetof(ParallelHeapScanDescData, phs_snapshot_data), - EstimateSnapshotSpace(snapshot)); + return add_size(offsetof(BTShared, heapdesc), + heap_parallelscan_estimate(snapshot)); } /* -- 2.50.1