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by wwilson 3367 days ago
(Disclaimer: I work on Cloud Spanner).

Cloud Spanner fully supports interactive read-write transactions.

I'm not sure what the source of the confusion here is. Maybe Daniel is using a new definition of "client-side interactive transactions" that I'm unfamiliar with. :)
2 comments
evanweaver 3367 days ago
Our source for that was this post: https://quizlet.com/blog/quizlet-cloud-spanner (SQL Dialect)

Maybe that's no longer the case?

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wwilson 3367 days ago
Yeah, I've read that post, and I have no idea where it gives the impression that we don't support interactive transactions. What paragraph are you looking at?

Could you be referring to the fact that we make you do writes via a mutation API rather than DML? Obviously that has no impact on interactivity...

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evanweaver 3367 days ago
Yes, our misunderstanding and we misinformed Daniel. Fixed, and thank you.

It would be cool to know why Spanner is like that.

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bdarnell 3367 days ago
(disclosure: CockroachDB founder) The reason I've heard is that Spanner uses a separate mutation API instead of SQL DML because of a quirk of its transaction model. Writes within a transaction are not visible to subsequent reads within the same transaction (source: https://cloud.google.com/spanner/docs/transactions#rw_transa...). This is different from other SQL databases, so the use of a different API forces you to think about your read/write transactions in a Spanner-specific way.

(FWIW, CockroachDB does not have this limitation - transactions can read their own uncommitted writes, just like in other databases)

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elvinyung 3367 days ago
+1, also curious about this. I speculated that Cloud Spanner is supposed to be F1[1], but the fact that F1 seems to fully support SQL DML makes this difference even more perplexing.

> Updates are also supported using SQL data manipulation statements, with extensions to support updating fields inside protocol buffers and to deal with repeated structure inside protocol buffers.

[1] https://research.google.com/pubs/pub41344.html

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abadid 3367 days ago
Sorry about that. As Evan said -- that sentence was based on something he told me. The post has now been fixed. My apologies.
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