Can I automatically populate `created_at` timestamp to transaction timestamp with Google Spanner?

Question

I am looking through the documentation for Google Cloud Spanner, and it looks like write operations return a timestamp when the row was actually written.

But when reading rows, it doesn't seem possible to re-capture that timestamp (either as a column that can be read or as a column that could be limited and sorted on).

I assume that I could just update the row after it is written to append a new column (created_at), but ideally it would be nice to have that field automatically appended.

Is there any way to access the original transaction timestamp when querying spanner? I also noticed that there was a CURRENT_TIMESTAMP() sql function. Is that equivalent to the transaction timestamp?

score 2 · Accepted Answer · answered Apr 16 '18 at 22:45

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You can create commit timestamp columns, and Cloud Spanner writes the timestamp as part of the transaction:

https://cloud.google.com/spanner/docs/commit-timestamp

answered Apr 16 '18 at 22:45

Robin

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Welcome to Stack Overflow! In the future, please include all relevant code in your post and **don't** just include a link to a code hosting site. Your post should stand alone from any other resource; [consider what would happen](https://en.wikipedia.org/wiki/Link_rot) if that site went down in the future! – Neuron Apr 16 '18 at 23:02

Identicon · Answer 2 · 2017-10-05T22:14:39.633

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Currently, updating the timestamp column is the closest we can get.

edited Oct 05 '17 at 22:14

answered Oct 03 '17 at 21:20

Identicon

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score 0 · Answer 3 · edited Mar 02 '18 at 00:22

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CURRENT_TIMESTAMP() returns the current time.

See for more information:
https://cloud.google.com/spanner/docs/functions-and-operators#current_timestamp

edited Mar 02 '18 at 00:22

K.Dᴀᴠɪs

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answered Mar 02 '18 at 00:05

Rose Liu

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Can I automatically populate `created_at` timestamp to transaction timestamp with Google Spanner?

3 Answers3