为提高效率，请提供以下信息，问题描述清晰能够更快得到解决：
【 TiDB 使用环境】
【概述】场景+问题概述
【背景】做过哪些操作
【现象】业务和数据库现象
【业务影响】
【TiDB 版本】4.0.12
【附件】
使用diff验证TiDB和MySQL数据一致性时，有这个警告：
[2021/08/18 15:03:09.722 +08:00] [WARN] [chunk.go:395] [“use tidb bucket information to get chunks failed, will split chunk by random again”] [“get chunk”=0] [error=“primary key on id in buckets info not found”] [errorVerbose="primary key on id in buckets info not found\ngithub.com/pingcap/errors.NotFoundf\
\t/go/pkg/mod/github.com/pingcap/errors@v0.11.5-0.20201126102027-b0a155152ca3/juju_adaptor.go:117\
github.com/pingcap/tidb-tools/pkg/dbutil.GetBucketsInfo\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/pkg/dbutil/common.go:480\
github.com/pingcap/tidb-tools/pkg/diff.(*bucketSpliter).split\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/pkg/diff/chunk.go:301\ngithub.com/pingcap/tidb-tools/pkg/diff.getChunksForTable\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/pkg/diff/chunk.go:390\
github.com/pingcap/tidb-tools/pkg/diff.SplitChunks\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/pkg/diff/chunk.go:453\
github.com/pingcap/tidb-tools/pkg/diff.(*TableDiff).CheckTableData\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/pkg/diff/diff.go:251\ngithub.com/pingcap/tidb-tools/pkg/diff.(*TableDiff).Equal\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/pkg/diff/diff.go:157\
main.(*Diff).Equal\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/sync_diff_inspector/diff.go:621\
main.checkSyncState\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/sync_diff_inspector/main.go:83\
main.main\
\t/home/jenkins/agent/workspace/optimization-build-tidb-linux-amd/go/src/github.com/pingcap/tidb-tools/sync_diff_inspector/main.go:65\
runtime.main\
\t/usr/local/go/src/runtime/proc.go:203\
runtime.goexi
看了一下，这个警告是由于主键信息不在直方图中，数据同步执行完，信息不在直方图中，不应该吧，这个是为什么呢？