I have following queries about RonDB:
Consider a column in a table of type
varbinary(255). Does it occupy entire space of 255 characters or 255 bytes if we store less data like 50 chars or 50 bytes?
Is there a TTL-like capability in RonDB? What I’m looking for some kind table level TTL, so any row inserted or updated before a x seconds will expire.
Is there any approach to store data in RonDB such that, it is served from memory but also persisted on disk? So even if all of the data nodes go down, data can restored from last persisted data on disk.
We experimented with backup and restore commands in RonDB. We had 4 data node setup with 256 GB RAM, replication 2. On issuing backup command, it produced backup files ~50 GB in each node and process took around 2.5 hours. While performing restore, we observed that time taken for data restore (ndb_restore --restore-data) varied in different data nodes (1 node took 6 hrs, 2 nodes took 9 hours, 1 node took close to 12 hours). On going through documentation, we came across MinDiskWriteSpeed and MaxDiskWriteSpeed parameters which defaults to 2MBps and 20MBps. If we increase these disk speeds by 5x or 10x, what kind of impacts would be there? Will it improve backup and restore time?