What RAG changes—and what it does not
How retrieval connects a language model to documents, and why a citation is not a guarantee.
AI / RAG / Retrieval
TECHNOLOGY / KNOWLEDGE / PRACTICE
AI, programming, SQL, Web and SAP: practical guides
Practical guides to AI, Python, Git, SQL, Web/API, SAP/ERP and mathematical models, with explanations, code examples, sources and limitations.
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1–8 / 8 guidesGit merge or rebase: choose by how the branch is shared
Preserve shared history or replay local work before integration.
Git / Merge / Rebase
401, 403, 429 or 503: where to start with an API error
Separate authentication, permissions, rate limits and service availability before retrying.
HTTP / API / Troubleshooting
Read a PostgreSQL EXPLAIN plan before adding an index
Find the expensive step and distinguish estimates from measurements.
PostgreSQL / SQL / Performance
Create a Python virtual environment without mixing dependencies
A small, repeatable setup for a project and a quick check that pip uses the right Python.
Python / venv / pip
What RAG changes—and what it does not
How retrieval connects a language model to documents, and why a citation is not a guarantee.
AI / RAG / Retrieval
SAP FI and CO: two views of the same transaction
Understand financial reporting, internal cost allocation and their connection in S/4HANA.
SAP / FI / CO / S/4HANA
Why SQL comparisons with NULL do not behave like zero
Understand IS NULL, three-valued logic and the difference between COUNT(*) and COUNT(column).
SQL / PostgreSQL / NULL
Validate a time-series forecast without leaking the future
Use chronological splits and fit preprocessing only on past data.
Python / Time series / Validation