Update docs/design/2024-01-22-ticdc-large-txn-not-block-wm.md

Co-authored-by: CharlesCheung <[email protected]>

docs/design/2024-01-22-ticdc-large-txn-not-block-wm.md

@@ -133,7 +133,7 @@ In order to decline the query QPS by many magnitude, we use store level requests
 
 CDC set a hook in TiKV's raft log applying module. CDC uses this hook to observe all data changes (key/value level prewrites(1st phase of 2PC) and commits(2nd phase of 2PC)) for specific data ranges. Meanwhile, TiKV's watermark (Resolve TS) mechanism periodically sends the latest watermark to CDC to notify downstream can consume all data that committed before this watermark.
 Inside CDC, there is an uncommitted data buffer named Matcher for each data range, the matcher caches all prewrite kvs until these kvs receive corresponding commit message and then move them to Sorter one by one.
-The Matcher is a kv-level map, when there is a transaction modified multiple rows, these rows will be moved from the Matcher to the Sorter one by one. Because each row will stay in the Matcher until it received its own commit message. The following diagram left part demostrates a transaction involves key0 and key1, when the Machter receive key1's commit message, it will only move key1 the Sorter (bold part). But at that point of time, the state of this transaction is determined and the commit ts of other keys of this transaction must be 101. key0 will be moved to the Sorter after it received "key0 commit, commit-ts = 101" message.
+The Matcher is a kv-level map, when there is a transaction modified multiple rows, these rows will be moved from the Matcher to the Sorter one by one. Because each row will stay in the Matcher until it received its own commit message. The following diagram left part demostrates a transaction involves key0 and key1, when the Machter receive key1's commit message, it will only move key1 to the Sorter (bold part). But at that point of time, the state of this transaction is determined and the commit ts of other keys of this transaction must be 101. key0 will be moved to the Sorter after it received "key0 commit, commit-ts = 101" message.
 After we use large transaction's min-commit-ts to calculate the watermark, the watermark of a data range might be advanced after it reiceived the 1st kv commit message for this transaction. This means CDC should move the whole transaction to the Sorter after CDC receives 1st kv commit message for this specific data range. The right part of following diagram demostrates this case:
 
 ![image](../media/large-txn-no-block-wm-7.png)