Question 1

Does change data capture work from PlanetScale into MotherDuck?

Accepted Answer

Yes, end to end. Changes stream out of PlanetScale through Vitess VStream and land in MotherDuck through its Parquet staging path, but staging is only the transport. Records are loaded into a staging table and then reconciled against the destination with update and insert statements, so an incremental run genuinely merges rather than appending a fresh copy of everything.

Question 2

How do shards appear on the MotherDuck side?

Accepted Answer

As one table per source table, not one per shard. Polytomic discovers the shards, subscribes across all of them, and checkpoints a position for each, so the sharding is an implementation detail of the source rather than something you model downstream. That consolidation is a large part of why teams replicate a sharded database into an analytical store in the first place.

Question 3

What happens to rows deleted in PlanetScale?

Accepted Answer

When the table has a primary key, deletes are captured and recorded in MotherDuck as soft deletes, marked with a deletion timestamp column rather than vanishing. That preserves history, which is usually what you want for analysis. Hard delete propagation is available if you would rather the rows were physically removed. Without a primary key the sync falls back to append and deletes cannot be tracked.

Question 4

Can MotherDuck write back into PlanetScale?

Accepted Answer

Yes, MotherDuck works as a source and PlanetScale accepts create, update, create or update, and replace modes. Two boundaries apply on the PlanetScale side: writes go into the single keyspace configured on the connection, and any table migration is still subject to your branch's safe migration rules, so a rebuild can be rejected by PlanetScale policy rather than by Polytomic.

Connect MotherDuck with PlanetScale Vitess

Connect MotherDuck and PlanetScale Vitess with Polytomic

Every shard, one table

Change capture through VStream

Analytics off the primaries

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Connect MotherDuck in Polytomic

Connect PlanetScale Vitess in Polytomic

Create a sync between MotherDuck and PlanetScale Vitess

Map fields and enable the sync

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