Update follower reads docs with another case #19953
Open
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Specifically, add the case that strong follower reads can occur under specific conditions even if you are not doing `SELECT ... AS OF SYSTEM TIME` or reading from a `GLOBAL` table.
✅ Deploy Preview for cockroachdb-interactivetutorials-docs canceled.
|
Files changed: |
✅ Deploy Preview for cockroachdb-api-docs canceled.
|
✅ Netlify Preview
To edit notification comments on pull requests, go to your Netlify project configuration. |
stevendanna
approved these changes
Jul 17, 2025
|
@stevendanna TFTR! what other versions of CockroachDB would you expect to show this behavior? I would like to backport this change to those versions, if any |
|
@rmloveland I'll have to do some historical git exploration to be 100% confident since the exact set of reads eligible for follow reads has expanded a bit over time. However, my expectation is that some form of this has been available for a long time (i.e. I'm pretty sure this is the behaviour in all supported versions) |
|
@stevendanna Does it increase the confidence level somewhat to exclude
the v23.* versions and just focus on v24.1+?
Totally understand if the answer is still "I need to do some historical
git exploration", just don't want this PR to sit too long if not
absolutely necessary. If you're pretty confident on v24.1+ I'd be happy
to run with that.
Steven Danna ***@***.***> writes:
… *
stevendanna left a comment (cockroachdb/docs#19953)
@rmloveland I'll have to do some historical git exploration to be 100%
confident since the exact set of reads eligible for follow reads has
expanded a bit over time. However, my expectation is that some form of
this has been available for a long time (i.e. I'm pretty sure this is
the behaviour in all supported versions)
—
Reply to this email directly, view it on GitHub, or unsubscribe.
You are receiving this because you were mentioned.
|
taroface
approved these changes
Jul 30, 2025
| @@ -18,7 +18,7 @@ The following table summarizes the read types and how to accomplish them. | |||
| | Strong Reads | Stale Reads | |||
| -----|-----------|---------------------------------------------------------------- | |||
| Only From Leaseholder | `SELECT` | N/A | |||
| From Nearest Replica | `SELECT` on `GLOBAL` table | `SELECT` with `AS OF SYSTEM TIME <historical-timestamp-function>` | |||
| From Nearest Replica | `SELECT` on a `GLOBAL` table *or* a long-running `SELECT` whose read timestamp has fallen behind the [closed timestamp]({% link {{ page.version.version }}/architecture/transaction-layer.md %}#closed-timestamps) | `SELECT` with `AS OF SYSTEM TIME <historical-timestamp-function>` | |||
There was a problem hiding this comment.
Suggested change
| From Nearest Replica | `SELECT` on a `GLOBAL` table *or* a long-running `SELECT` whose read timestamp has fallen behind the [closed timestamp]({% link {{ page.version.version }}/architecture/transaction-layer.md %}#closed-timestamps) | `SELECT` with `AS OF SYSTEM TIME <historical-timestamp-function>` | |
| From Nearest Replica | `SELECT` on a `GLOBAL` table **or** a long-running `SELECT` whose read timestamp has fallen behind the [closed timestamp]({% link {{ page.version.version }}/architecture/transaction-layer.md %}#closed-timestamps) | `SELECT` with `AS OF SYSTEM TIME <historical-timestamp-function>` |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Specifically, add the case that strong follower reads can occur under specific conditions even if you are not doing
SELECT ... AS OF SYSTEM TIMEor reading from aGLOBALtable.