Skip to content

DOC-614 | Async prefetching AQL optimizer rule #410

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

Merged
merged 2 commits into from
Jan 15, 2024
Merged

DOC-614 | Async prefetching AQL optimizer rule #410

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
13b702c
Async prefetching AQL optimizer rule
Simran-B Jan 4, 2024
a93cbcb
Merge branch 'main' of https://github.com/arangodb/docs-hugo into asy…
Simran-B Jan 12, 2024
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
25 changes: 25 additions & 0 deletions site/content/3.12/release-notes/version-3.12/whats-new-in-3-12.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,31 @@ less overhead.

See [Document and object functions in AQL](../../aql/functions/document-object.md#parse_collection).

### Parallel execution within an AQL query

The new `async-prefetch` optimizer rule allows certain operations of a query to
asynchronously prefetch the next batch of data while processing the current batch,
allowing parts of the query to run in parallel. This can lead to performance
improvements if there is still reserve (scheduler) capacity.

The new `Par` column in a query explain output shows which nodes of a query are
eligible for asynchronous prefetching. Write queries, graph execution nodes,
nodes inside subqueries, and query parts involving remote execution are not
eligible.

```aql
Execution plan:
Id NodeType Par Est. Comment
1 SingletonNode 1 * ROOT
2 EnumerateCollectionNode ✓ 18 - FOR doc IN places /* full collection scan */ FILTER (doc.`label` IN [ "Glasgow", "Aberdeen" ]) /* early pruning */
5 CalculationNode ✓ 18 - LET #2 = doc.`label` /* attribute expression */ /* collections used: doc : places */
6 SortNode ✓ 18 - SORT #2 ASC /* sorting strategy: standard */
7 ReturnNode 18 - RETURN doc
```

The profiling output for queries includes a new `Par` column as well, but it
shows the number of successful parallel asynchronous prefetch calls.

## Indexing

### Stored values can contain the `_id` attribute
Expand Down