Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Additional v23.1 Known Limitations #16902

Merged
merged 5 commits into from
May 15, 2023
Merged

Additional v23.1 Known Limitations #16902

Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
a647109
Additional v23.1 Known Limitations
May 9, 2023
c03ef26
Add KL92961
May 9, 2023
4b3296c
Update CDC KL
May 9, 2023
70965ab
Edits based on feedback
May 10, 2023
edee007
Minor fix
May 15, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
54 changes: 48 additions & 6 deletions v23.1/known-limitations.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -30,17 +30,59 @@ This page describes newly identified limitations in the CockroachDB {{page.relea

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/84680)

### No support for placeholders in `AS OF SYSTEM TIME`
### Limitations for `SELECT FOR UPDATE`

CockroachDB does not support placeholders in [`AS OF SYSTEM TIME`](as-of-system-time.html). This means that the time value has to be embedded in the SQL string.
- [`SELECT FOR UPDATE`](select-for-update.html) places locks on each key scanned by the base index scan. This means that even if some of those keys are later filtered out by a predicate which could not be pushed into the scan, they will still be locked.

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/30955)
[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/75457)

- [`SELECT FOR UPDATE`](select-for-update.html) only places an unreplicated lock on the index being scanned by the query. This diverges from PostgreSQL, which aquires a lock on all indexes.

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/57031)

### Limitations for composite types

- Avro [changefeeds](create-and-configure-changefeeds.html) do not support user-defined composite (tuple) types.

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/102903)

- Parquet [changefeeds](create-and-configure-changefeeds.html) do not support user-defined composite (tuple) types.
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yes, this can be removed from here.

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh sorry @lnhsingh I just saw this was merged. I am working on an issue related to this right now, I can remove!

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thank you!


[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/102904)

- Serializing a user-defined composite (tuple) type to CSV is in [preview](cockroachdb-feature-availability.html): the output format is likely to change in a future minor release, and alterations to the type may not be reflected properly in changefeeds.
mdlinville marked this conversation as resolved.
Show resolved Hide resolved

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/102905)

### Common table expressions are not supported in user-defined functions

[Common table expressions](common-table-expressions.html) (CTE), recursive or non-recursive, are not supported in [user-defined functions](user-defined-functions.html) (UDF). That is, you cannot use a `WITH` clause in the body of a UDF.

### `SELECT FOR UPDATE` places locks on each key scanned by the base index scan
[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/92961)

[`SELECT FOR UPDATE`](select-for-update.html) places locks on each key scanned by the base index scan. This means that even if some of those keys are later filtered out by a predicate which could not be pushed into the scan, they will still be locked.
### Low estimated Request Units are rounded to zero

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/75457)
The [Request Units](../cockroachcloud/learn-about-request-units.html) (RUs) estimate surfaced in [`EXPLAIN ANALYZE`](explain-analyze.html) is displayed as an integer value. Because of this, fractional RU estimates, which represent very inexpensive queries, are rounded down to zero.

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/100617)

### Statistics for deleted tables in `system.table_statistics` do not get removed

When a table is dropped, the related rows in `system.table_statistics` are not deleted. CockroachDB does not delete historical statistics.

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/94195)

### Collection of statistics for virtual computed columns

CockroachDB does not collect statistics for [virtual computed columns](computed-columns.html). This can prevent the [optimizer](cost-based-optimizer.html) from accurately calculating the cost of scanning an index on a virtual column, and, transitively, the cost of scanning an [expression index](expression-indexes.html).

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/68254)

### `AS OF SYSTEM TIME` does not support placeholders

CockroachDB does not support placeholders in [`AS OF SYSTEM TIME`](as-of-system-time.html). The time value must be embedded in the SQL string.

[Tracking GitHub issue](https://github.com/cockroachdb/cockroach/issues/30955)

### Declarative schema changer does not track rows in `system.privileges`

Expand Down