From 400eaa29bcf27cbd6e560614f6fb8e46a2bf5842 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Mon, 16 Apr 2018 20:51:08 +1200 Subject: [PATCH] Don't count zero-filled buffers as 'read' in EXPLAIN. If you extend a relation, it should count as a block written, not read (we write a zero-filled block). If you ask for a zero-filled buffer, it shouldn't be counted as read or written. Later we might consider counting zero-filled buffers with a separate counter. Author: Thomas Munro Reviewed-by: Haribabu Kommi, Kyotaro Horiguchi, David Rowley Discussion: https://postgr.es/m/CAEepm%3D3JytB3KPpvSwXzkY%2Bdwc5zC8P8Lk7Nedkoci81_0E9rA%40mail.gmail.com --- src/backend/storage/buffer/bufmgr.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 01eabe57063..9817770affc 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -733,7 +733,10 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum, bufHdr = LocalBufferAlloc(smgr, forkNum, blockNum, &found); if (found) pgBufferUsage.local_blks_hit++; - else + else if (isExtend) + pgBufferUsage.local_blks_written++; + else if (mode == RBM_NORMAL || mode == RBM_NORMAL_NO_LOG || + mode == RBM_ZERO_ON_ERROR) pgBufferUsage.local_blks_read++; } else @@ -746,7 +749,10 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum, strategy, &found); if (found) pgBufferUsage.shared_blks_hit++; - else + else if (isExtend) + pgBufferUsage.shared_blks_written++; + else if (mode == RBM_NORMAL || mode == RBM_NORMAL_NO_LOG || + mode == RBM_ZERO_ON_ERROR) pgBufferUsage.shared_blks_read++; } -- 2.19.1