From 59af8d4384ba5ae72986eab7e5cdc514a969aa05 Mon Sep 17 00:00:00 2001 From: Simon Riggs Date: Mon, 27 Nov 2017 09:34:05 +0000 Subject: [PATCH] Pad XLogReaderState's per-buffer data_bufsz more aggressively. Originally, we palloc'd this buffer just barely big enough to hold the largest xlog backup block seen so far. We now MAXALIGN the palloc size. The original coding could result in many repeated palloc cycles, in the worst case where we see a series ofgradually larger xlog records. We ameliorate that similarly to 8735978e7aebfbc499843630131c18d1f7346c79 by imposing a minimum buffer size of BLCKSZ. Discussion: https://postgr.es/m/E1eHa4J-0006hI-Q8@gemulon.postgresql.org --- src/backend/access/transam/xlogreader.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c index fa9432eb67..0a75c36026 100644 --- a/src/backend/access/transam/xlogreader.c +++ b/src/backend/access/transam/xlogreader.c @@ -1264,7 +1264,13 @@ DecodeXLogRecord(XLogReaderState *state, XLogRecord *record, char **errormsg) { if (blk->data) pfree(blk->data); - blk->data_bufsz = blk->data_len; + + /* + * Force the initial request to be BLCKSZ so that we don't + * waste time with lots of trips through this stanza as a + * result of WAL compression. + */ + blk->data_bufsz = MAXALIGN(Max(blk->data_len, BLCKSZ)); blk->data = palloc(blk->data_bufsz); } memcpy(blk->data, ptr, blk->data_len);