Feat: Add maxItemCount option for pagination

[andrejpk]

Implements the maxItemCount option in findManyByQuery to allow users to control the number of items returned per page from Cosmos DB.

This change:

• Adds maxItemCount as a direct option in QueryFindArgs.
• Updates findManyByQuery to use iterator.fetchNext() to respect pagination, instead of fetchAll().
• Includes integration tests to verify maxItemCount functionality with the CosmosDB simulator.
• Updates README documentation.

[llamapreview]

Auto Pull Request Review from LlamaPReview

1. Overview

1.1 Core Changes

• Primary purpose and scope: Implement pagination control via maxItemCount option for Cosmos DB queries
• Key components modified:
  • Query arguments interface in src/datasource.ts
  • Query execution logic in findManyByQuery
  • Integration tests and documentation
• Cross-component impacts: Changes default query behavior from full dataset to first page retrieval
• Business value alignment: Enables efficient handling of large datasets and improves query performance

1.2 Technical Architecture

• System design modifications: Introduces pagination control layer in data access pattern
• Component interaction changes: Alters relationship between query execution and result handling
• Integration points impact: Affects all consumers using findManyByQuery method
• Dependency changes: Requires proper handling of Cosmos DB iterator patterns

2. Critical Findings

2.1 Must Fix (P0🔴)

Issue: Breaking backward compatibility in query results retrieval

• Analysis Confidence: High
• Impact: Existing implementations expecting full dataset will receive partial results, potentially causing production failures
• Resolution: Restore fetchAll() as default behavior, use fetchNext() only when maxItemCount is set

Issue: Incomplete pagination implementation

• Analysis Confidence: High
• Impact: Users cannot retrieve full datasets when using pagination due to missing continuation token support
• Resolution: Add continuation token parameter and documentation for multi-page navigation

2.2 Should Fix (P1🟡)

Issue: Insufficient documentation for pagination workflow

• Analysis Confidence: High
• Impact: Users won't understand how to implement complete pagination solution
• Suggested Solution: Add documentation for continuation token usage and multi-page retrieval examples

Issue: Potentially unreliable simulator-based tests

• Analysis Confidence: Medium
• Impact: Test assertions about hasMoreResults might not reflect real CosmosDB behavior
• Suggested Solution: Add validation against real CosmosDB instance or document simulator limitations

2.3 Consider (P2🟢)

Area: Iterator resource management

• Analysis Confidence: Medium
• Improvement Opportunity: Prevent memory leaks by implementing proper iterator cleanup

Area: Error handling robustness

• Analysis Confidence: Low
• Improvement Opportunity: Add explicit error handling for pagination operations

2.4 Summary of Action Items

1. Immediate (Pre-Merge):
   • Restore backward compatibility in query execution
   • Add continuation token support
2. Within 1 Sprint:
   • Update documentation with pagination workflow
   • Enhance test reliability
3. Future Roadmap:
   • Implement advanced iterator management
   • Add async pagination interface

3. Technical Analysis

3.1 Code Logic Analysis

📁 src/datasource.ts - findManyByQuery

• Submitted PR Code:

    const iterator = this.container.items.query<TData>(query, finalRequestOptions);
    const results = await iterator.fetchNext();

• Analysis:
  • Changes default behavior from full dataset retrieval to first page only
  • Breaks existing implementations expecting complete results
  • No error handling for pagination-specific operations
  • Impacts all consumers of this data source method
• LlamaPReview Suggested Improvements:

    let results: FeedResponse<TData>;
    if (finalRequestOptions.maxItemCount !== undefined) {
      results = await iterator.fetchNext(); // Pagination mode
    } else {
      results = await iterator.fetchAll(); // Backward-compatible default
    }

• Improvement rationale:
  • Maintains backward compatibility while enabling new feature
  • Prevents breaking changes for existing consumers
  • Clear feature boundary between paginated/non-paginated use

📁 src/datasource.ts - CosmosQueryDbArgs

• Submitted PR Code:

    export interface CosmosQueryDbArgs {
      requestOptions?: FeedOptions;
      maxItemCount?: number;
    }

• Analysis:
  • Missing continuation token support prevents multi-page navigation
  • Users cannot progress through paginated results
  • Limits usefulness of pagination feature
• LlamaPReview Suggested Improvements:

    export interface CosmosQueryDbArgs {
      requestOptions?: FeedOptions;
      maxItemCount?: number;
      continuationToken?: string; // Added support
    }

• Improvement rationale:
  • Enables complete pagination workflow
  • Aligns with CosmosDB pagination requirements
  • Provides necessary tools for full dataset traversal

3.2 Key Quality Aspects

• Testing strategy: Simulator limitations may create false positives for pagination behavior
• Documentation needs: Critical missing guidance on pagination implementation details
• System scalability: Pagination support enables better large dataset handling
• Performance: Properly implemented pagination reduces initial load times

4. Overall Evaluation

• Technical assessment: Valuable feature implementation with critical compatibility issues
• Business impact: High value performance improvement with moderate implementation risk
• Risk evaluation: High risk of breaking existing implementations without fixes
• Notable positive aspects:
  • Comprehensive test coverage for new functionality
  • Clear option precedence handling (maxItemCount vs requestOptions)
  • Good logging implementation
• Implementation quality: Functional but incomplete implementation requiring adjustments
• Final recommendation: Request Changes (Must address P0 issues before merge)

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