意思是当 有 binlog 就意味着 已经读完了 snapshot
casel.chen <casel_c...@126.com> 于2023年12月19日周二 16:45写道：
> 我在阅读flink-connector-mysql-cdc项目源码过程中遇到一个不清楚的地方，还请大佬指点，谢谢！
>
>
> MySqlSplitReader类有一段代码如下，注释“(1) Reads binlog split firstly and then read
> snapshot split”这一句话我不理解。
> 为什么要先读binlog split再读snapshot split？为保证记录的时序性，不是应该先读全量的snapshot
> split再读增量的binlog split么？
>
>
> private MySqlRecords pollSplitRecords() throws InterruptedException {
> Iterator<SourceRecords> dataIt;
> if (currentReader == null) {
> // (1) Reads binlog split firstly and then read snapshot split
> if (binlogSplits.size() > 0) {
> // the binlog split may come from:
> // (a) the initial binlog split
> // (b) added back binlog-split in newly added table process
> MySqlSplit nextSplit = binlogSplits.poll();
> currentSplitId = nextSplit.splitId();
> currentReader = getBinlogSplitReader();
> currentReader.submitSplit(nextSplit);
> } else if (snapshotSplits.size() > 0) {
> MySqlSplit nextSplit = snapshotSplits.poll();
> currentSplitId = nextSplit.splitId();
> currentReader = getSnapshotSplitReader();
> currentReader.submitSplit(nextSplit);
> } else {
> LOG.info("No available split to read.");
> }
> dataIt = currentReader.pollSplitRecords();
> return dataIt == null ? finishedSplit() : forRecords(dataIt);
> } else if (currentReader instanceof SnapshotSplitReader) {
> ....
> }
> ...
> }
