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

ESQL: planning perf improvements over many fields #124395

Open
15 tasks
costin opened this issue Mar 8, 2025 · 1 comment
Open
15 tasks

ESQL: planning perf improvements over many fields #124395

costin opened this issue Mar 8, 2025 · 1 comment
Labels
:Analytics/ES|QL AKA ESQL >enhancement Team:Analytics Meta label for analytical engine team (ESQL/Aggs/Geo)

Comments

@costin
Copy link
Member

costin commented Mar 8, 2025

Description

We've noticed that planning shows up in the profiler when dealing with huge mappings (10k-100k+ fields).
Overall the goal is to add conditional and prevent code for execution on such large number of objects by avoid iteration in the first place.
This meta issue contains a list of (potential) improvements to apply to improve performance in this scenario broken down in two main buckets:

Avoiding execution

  • rules working on expressions should perform basic assertion to check whether the logic has to be applied or not, such as checking the size of the collection or attributes.

  • avoid creating new AttributeMap/Set by making the collection immutable again so it can be safely passed around
    (wrap the add/removeIf/delete methods through an utility class so they can be passed only for newly created
    objects).

  • avoid collection copying unless needed
    Node#transformChildren and QueryPlan#doTransformExpression create a new Array based on the size of
    the children all the time. This should be done lazy and potentially different (clone()).

  • double check array sorting - Analyzer#278/279

  • ProjectAwayColumns always creates an output set clone - 44/83/84

Optimized execution of existing code

  • LogicalVerifier#verify

  • PruneColumns

  • PropagateUnmappedFields

  • PropagateEvalFoldables

  • stop using super inside TypedAttribute/NamedExpression/Attribute/FieldAttribute equals

Currently the equals method delegate to their parent which helps with code but also causes suboptimal equality since the children of the node are compared before the attributes. Better to compare all the node properties first and delegate to the collection as a last result.

  • use collection hashing before performing attributes equality
    to avoid comparing large collections, use a hash comparison first before iterating over the collection

  • optimize Node#forEachProperty
    prop != children && children.contains(prop) == false && typeToken.isInstance(prop) -->
    prop != children && typeToken.isInstance(prop) && children.contains(prop) == false

  • look in removing/replacing children.contains(prop) inside Node#forEachProperty
    A (linkedhashSet) set would work better and preserve order however it would prevent a child to appear more than once. This can be an issue in projection with duplicate fields (keep a,a,a).

  • optimize NameId#hashCode to avoid array boxing (use Long.hashCode(id) instead)

  • replace Java stream api with regular for-loop

Though brief, stream(), collect(), reduce() & co are slower than their equivalent foreach and pollute the stack trace. They have an edge in parallel processing which, depending on the data size, could yield better results however that's not the case here.

@costin costin added >enhancement needs:triage Requires assignment of a team area label labels Mar 8, 2025
costin added a commit to costin/elasticsearch that referenced this issue Mar 8, 2025
A set of optimization for tree traversal:
1. perform lazy copying during children transform
2. use long hashing to avoid object creation
3. perform type check first before collection checking

Relates elastic#124395
@pxsalehi pxsalehi added :Analytics/ES|QL AKA ESQL and removed needs:triage Requires assignment of a team area label labels Mar 10, 2025
@elasticsearchmachine elasticsearchmachine added the Team:Analytics Meta label for analytical engine team (ESQL/Aggs/Geo) label Mar 10, 2025
@elasticsearchmachine
Copy link
Collaborator

Pinging @elastic/es-analytical-engine (Team:Analytics)

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
:Analytics/ES|QL AKA ESQL >enhancement Team:Analytics Meta label for analytical engine team (ESQL/Aggs/Geo)
Projects
None yet
Development

No branches or pull requests

3 participants