SAP HANA 2.0 Administration · Performance Analysis: SQL Tuning & Plan Analysis

An incident happened 2 weeks ago and you go to M_LOAD_HISTORY_* for the load picture. Why might the data already be gone, and what's the danger of tightening the sampling to catch more?

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More in Performance Analysis: SQL Tuning & Plan Analysis

You open PlanViz on a slow statement and want the fastest read on where the time went. Where do you look first, and what does it tell you?

A specific SQL statement from a packaged app (source you can't edit) consistently picks a bad plan. You want a fix that survives recompiles and needs no code change. Statement hint or explicit hint, and what decides?

Your query against M_SYSTEM_DATA_STATISTICS to survey statistics across all tables returns an error instead of a result set. Why, and what's the constraint you missed?

A junior admin reads an SAP HANA execution plan top-to-bottom and concludes the first listed operator runs first. Why is that backwards, and how is the true order reconstructed?

After a failover to the secondary host, you open M_LOAD_HISTORY_HOST/SERVICE to investigate the pre-failover load and they're empty. Is the history lost, and where do you actually look?

A production statement performs badly, but re-typing its SQL into EXPLAIN PLAN gives a different (fine) plan. What EXPLAIN PLAN option gets you the plan the optimizer actually chose in production?

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