Hello, I have an interesting situation where some .IBD files on a master are smaller than on all slaves replicating from it. Normally we expect that this would happen in the reverse order where the master has larger .IBD files. All the slaves have very close sizes. I’m looking for any input on why…

Hello @ChrisDK , Check how much free space is in the tablespace (.ibd file) between the two servers. It’s possible that on the source the table was rebuilt and free space was reclaimed.

Hi Matthew, Thanks for your input. I know for fact that the table was not rebuilt on the master. Any other ideas? It’s a little alarming to see this happening. Thanks, Chris

Did you check free space as I suggested?

Free space does not appear to be a factor. I checked on 1 table where the difference is many GBs. Please note I have masked the results. Query: SELECT table_name, → sum( data_length + index_length ) / 1024 / 1024 “DB size in MB”, → sum( data_free )/ 1024 / 1024 “free/reclaimable space in MB” …

[image] ChrisDK: ‘tabletesting Just some more info. Looking at the file level we see the sizes considerably larger on the slave. master -rw-r----- 1 mysql mysql 589G May 31 14:39 tabletesting#P#p5.ibd -rw-r----- 1 mysql mysql 480G Apr 6 12:36 tabletesting#P#p3.ibd -rw-r----- 1 mysql mysq…

Have a look at this recent post and Yves’s answer. [image] Disk Divergence across Master and Slaves Percona Server for MySQL 5.7 So, InnoDB stores rows in b-trees. Pages in a b-tree can be anywhere between half filled (50%) and filled (100%). Let’s assume there is a long r…

Thanks. I’ve added a few comments in the thread you provided. One interesting thing that I’ve noted based on Yves’s answer is that we have 2 slaves both replicating from the same master. The slaves have the exact same data sizes (smaller than master) and yet they are used in very different ways. O…

MySQL 5.7 - some .IBD files 15% smaller on master than on slaves

MySQL & MariaDB

matthewb May 31, 2023, 7:35pm 7

Have a look at this recent post and Yves’s answer.

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MySQL 5.7 - some .IBD files 15% smaller on master than on slaves

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