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Why can’t hash based partitioning systems just store the full hash with the key for fast rehashing if the number of buckets needs to change, or else recompute t
by meisel 3y ago
Why can’t hash based partitioning systems just store the full hash with the key for fast rehashing if the number of buckets needs to change, or else recompute the hash?
- dangoodmanUT 3y agoA few main reasons come to mind: 1. The hash would be an extra column that can be calculated from existing data, wasted storage 2. You effectively have to rewrite the entire database to itself to redistribute, and keeping the DB availabile during this process is _very_ complicated 3. You're putting an extreme load on the DB for a substantial amount of time. This takes away from your DB performance and makes node downtime even more severe In a distributed DB, you have to remember that the probability your node _doesn't_ have the data you need increases with the size of the cluster, which creates a negative feedback loop for having to rewrite.