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AI, programming, SQL, Web and SAP: guides and tips

Materials on AI, Python, Git, SQL, Web/API, SAP/ERP, statistics and time series: explanations, examples, practical tips, sources and applicability limits.

Latest guides

1-24 / 51 materials

Using LIMIT and OFFSET in PostgreSQL: Best Practices, Performance Impacts, and Alternatives

This guide explains how LIMIT and OFFSET work in PostgreSQL, their use cases for pagination, why large OFFSET values cause performance issues, and when to switch to cursor-based pagination. It includes syntax examples, mandatory ORDER BY requirements, common pitfalls, and alternative methods aligned with PostgreSQL and GitHub REST API standards.

PostgreSQL / database pagination / LIMIT / OFFSET / cursor-based pagination / query performance

Segmented Reporting in SAP S/4HANA: Balancing for Business Units

This document outlines how to configure document splitting within SAP S/4HANA to enable balance sheets for multiple business segments, leveraging the Universal Journal. It details the benefits of this approach, including the elimination of reconciliation efforts and the creation of granular financial reports. We cover the key organizational elements - Chart of Accounts and Ledger Unit - and how they interact with segment reporting.

SAP S/4HANA / Universal Journal / Segment Reporting / Financial Accounting / Controlling / Document Splitting / Balance Sheets / Reporting

Understanding Semantic Search: How it Works and Why Similar Text Might Not Answer Your Question

Explore the principles of semantic search, its reliance on embeddings, and the reasons why text that appears similar might not provide the desired answer. Learn about vector search, hybrid search, and their applications in information retrieval.

semantic search / vector search / embeddings / AI / information retrieval / natural language processing / hybrid search / Azure AI Search

AI Precision and Recall Evaluation on Small Datasets

Learn how to effectively evaluate the precision and recall of AI models, especially when working with small question datasets. This guide covers the concepts, calculation methods, and practical considerations using scikit-learn.

ai / precision / recall / evaluation / small dataset / machine learning / scikit-learn / classification

Choosing Between MAE and RMSE for Error Prediction

Understand the differences between Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE), how to choose the right metric for your prediction task, and the impact of large errors on each.

regression / model evaluation / MAE / RMSE / error metrics / scikit-learn / machine learning

API Pagination: Offset vs. Cursor for Changing Data

Understand the differences between offset-based and cursor-based pagination and when to use each, especially when dealing with frequently changing datasets.

api / pagination / rest / offset / cursor / data consistency / web development

Evaluating prediction intervals with empirical coverage and width

Prediction intervals aim to contain future individual observations, while confidence intervals target a mean or other parameter, and the two are not interchangeable. Empirical coverage is the held-out fraction inside the interval and width is the distance between quantile limits; a constructed five-value example gives 80 percent coverage and mean width 1.8.

prediction interval / confidence interval / quantile regression / empirical coverage / interval width / scikit-learn / calibration / held-out evaluation

Safe Cross-Platform Path Handling in Python with pathlib

A practical guide to using pathlib for file existence checks, extension manipulation, directory navigation, and path resolution without introducing platform-specific bugs on Windows or Unix systems.

pathlib / cross-platform / python / file-system / os.PathLike / PurePath / glob / resolve

Choosing RAG Chunk Boundaries and Overlap to Preserve Section Context

This article explains how to choose effective chunk boundaries and overlap in retrieval-augmented generation (RAG) systems, comparing fixed-size and document-aware strategies. Using a hypothetical support note example, it demonstrates the risks of splitting across semantic units and shows how metadata and overlap can preserve context. The guidance is based on Microsoft Azure documentation for chunking in vector search and RAG workflows.

RAG / chunking / Azure AI Search / information retrieval / document processing

Verifying RAG Citations: Beyond Source Existence to Claim Support

A citation identifier only proves a source was retrieved, not that it supports the claim. This article shows how to decompose answers, locate supporting passages, and separate retrieval checks from groundedness checks using a hypothetical policy example.

RAG / citation verification / groundedness / retrieval evaluation / prompt engineering / LLM evaluation