From 897a966f6fa1044acda123cdccda58e02ab8f9f8 Mon Sep 17 00:00:00 2001 From: Ti Chi Robot Date: Tue, 20 Feb 2024 15:06:26 +0800 Subject: [PATCH] Update syncpoint doc (#16512) (#16525) --- ticdc/ticdc-upstream-downstream-check.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/ticdc/ticdc-upstream-downstream-check.md b/ticdc/ticdc-upstream-downstream-check.md index 25b8475b0f112..6920a53170dbf 100644 --- a/ticdc/ticdc-upstream-downstream-check.md +++ b/ticdc/ticdc-upstream-downstream-check.md @@ -36,7 +36,7 @@ sync-point-retention = "1h" > **Note:** > -> Before you perform consistent snapshot read, make sure that you have [enabled the Syncpoint feature](#enable-syncpoint). +> Before you perform consistent snapshot read, make sure that you have [enabled the Syncpoint feature](#enable-syncpoint). If multiple replication tasks use the same downstream TiDB cluster and have Syncpoint enabled, each of these tasks updates `tidb_external_ts` and `ts-map` based on their respective replication progress. In this case, you need to set up consistent snapshot read at the replication task level by reading records from the `ts-map` table. Meanwhile, you need to avoid downstream applications reading data using `tidb_enable_external_ts_read`, because multiple replication tasks might interfere with each other and result in inconsistent results. When you need to query the data from the backup cluster, you can set `SET GLOBAL|SESSION tidb_enable_external_ts_read = ON;` for the application to obtain transactionally consistent data on the backup cluster.