René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"DynamoDB online_read ignores requested_features parameter","articleBody":"## Expected Behavior \nWhen calling get_online_features() with a subset of features (e.g., [\"fv:feature_a\", \"fv:feature_b\"]), the DynamoDB online store should only fetch those specific features using DynamoDB's ProjectionExpression. This reduces data transfer, lowers latency, and decreases read costs.\n\n## Current Behavior\nThe requested_features parameter is passed through the call chain to online_read() and online_read_async() but is completely ignored. DynamoDB's BatchGetItem fetches all features stored in the values map regardless of what features were requested.\n```\n# In dynamodb.py line 559-560\nasync def online_read_async(\n    ...\n    requested_features: Optional[List[str]] = None,  # Parameter accepted but unused\n)\n```\nThe BatchGetItem call does not include ProjectionExpression:\n```\n# Current implementation (line 619-621)\nclient.batch_get_item(\n    RequestItems=entity_id_batch,  # No ProjectionExpression\n)\n\n```\n## Steps to reproduce\n```\nfrom feast import FeatureStore\n\nfs = FeatureStore(repo_path=\".\")\n\n# Request only 2 features out of 200 stored\nresponse = fs.get_online_features(\n    features=[\"my_fv:feature_a\", \"my_fv:feature_b\"],  # Only 2 features\n    entity_rows=[{\"entity_id\": \"user_1\"}]\n)\n\n# Expected: DynamoDB fetches only feature_a, feature_b\n# Actual: DynamoDB fetches all 200 features, wastes bandwidth\n```\n\n### Specifications\n\n - Version: 0.60.0 and latest master\n- Platform: Any (tested on OpenShift/Kubernetes)\n- Subsystem: feast.infra.online_stores.dynamodb\n\n## Possible Solution\nAdd ProjectionExpression to BatchGetItem requests when requested_features is specified\n","author":{"url":"https://github.com/abhijeet-dhumal","@type":"Person","name":"abhijeet-dhumal"},"datePublished":"2026-03-04T09:36:52.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/6058/feast/issues/6058"}