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.

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

Control the number of rows returned by child executor #9166

Open
qw4990 opened this issue Jan 24, 2019 · 0 comments
Open

Control the number of rows returned by child executor #9166

qw4990 opened this issue Jan 24, 2019 · 0 comments
Assignees
Labels
sig/execution SIG execution

Comments

@qw4990
Copy link
Contributor

qw4990 commented Jan 24, 2019

Feature Request

Is your feature request related to a problem? Please describe:

TiDB uses chunk to carry data from children to parents, but the num of rows returned by children can’t be controlled by parents.
Most of the time, children return 1024 rows, which is the default size.
That is inappropriate in some cases, for example the parent is LimitN, which only needs N rows.

Describe the feature you'd like:

After this PR(#8994), chunk has been replaced to RecordBatch.
So we can add a new field RequiredRows to indicate the number of rows parents want.
And children use it to determine the number of rows returned to parents, which can improve efficiency in some cases.

Describe alternatives you've considered:

No.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
sig/execution SIG execution
Projects
None yet
Development

No branches or pull requests

1 participant