How to read the checksums table

MySQL & MariaDB Percona XtraDB Cluster 8.x
1

Hi Everyone,

We got a percona mysql cluster and one of these servers has a physical replication to a fourth server.

We want to check if the this 4th server matches with the percona cluster.

For this we use pt-table-checksum the results of this check is written to checksums_20250325_Mar.

How do we read this table? What do the following columns mean. Is this described somewhere? In here I do not find it: pt-table-checksum — Percona Toolkit Documentation

chunk
chunk_time
chunk_index
lower_boundary
upper_boundary
this_crc
this_cnt
master_crc
master_cnt

2

Hello @rkuijk,
Run this on the replica:
SELECT COUNT(*), db, tbl FROM percona.checksums WHERE this_crc != master_crc GROUP BY db, tbl

It will show you a count of the number of chunks that are different between source, and replica, grouped by db.table.

“this_crc” and “this_cnt” are the CRC checksum, and row counts as calculated on “this” server. If you are looking at node1, then “this” means node1. If you look at node42233, this “this” means node42233. “master_crc” and “master_cnt” are similar, but are a copy from the upstream source so that you can compare “this” (ie: local) to source.