That’s not contradictory?
It’s very common for scale-out architectures to read more data than is ultimately returned, because the former is pulled from individual shards and then some centralized filtering / post processing is applied in some API middleware layer.
Trying to fix that by pushing down more of the query/execution is sometimes but not always feasible or practical.
Re:PlanetScale Scaler Pro
by semiquaver on Thursday July 06, 2023 @03:05PM
(#36621152)
(responding to GP) “Full table scans are expensive” is a better way to reframe the pricing model (at least before this pricing change). The distinction is between rows _examined_ vs rows _returned to a db client_. Even the latter is a tricky concept with vitess since it’s a routing/sharding system that sits on top of vanilla MySQL instances.
The value I found is being able to do multi-region read replicas with no compute overhead for lower traffic geos.
I like the idea of PS and have toyed around with the idea of migrating to it but there are some glaring issues I don’t want to deal with:
- no native way to export backups and avoid vendor lock in (or pay for the row reads to generate regular backups)
- contradictory cost model. Their pricing page reads “Every time a query retrieves a row from the database, it is counted as a row read. Every time a row is written to the database, it is counted as a row written.” while their docs state “Rows read is a measure of the work that the database engine does, not a measure of the number of rows returned. Every row read from a table during execution adds to the rows read count, regardless of how many rows are returned.”