Quiz Catalogue

This is a list of all “quiz night” / “quiz time” articles I’ve written. Most of them will appear in some other catalogue since they were intended to highlight some little detail of how Oracle behaves. The articles are generally listed most-recent first.

I am currently working backwards through my entire blog adding articles to catalogues as I go, so any individual catalogue may grow very slowly.

• Quiz night 39 (Jan 2023): how do you get “parallel query checkpointing” without parallel queries?
• Quiz night 38 (Jan 2023): what really happens when you try to gather stats on a single column
• Quiz night 37 (May 2022): why avg_row_len may give you a very bad estimate of the space needed by your table data.
• Quiz night 36 (Sept 2021): explaining why “tablescan rows gotten” may be much (much) larger than you expect from a pl/sql loop.
• Quiz night 35 (July 2021): the disappearing NOT NULL declaration – a critical detail about primary key constraints, with links to notes about adding and dropping primary (or unique) keys.
• Quiz night 34 (Sept 2019): changes to undo and redo for “no change” updates as we move through newer versions of Oracle.
• Quiz Night 33 (July 2018): how does Oracle handle sorting “count(distinct …)”
• Quiz Night 32 (April 2017): what pointers to you get from the summary lines of this tkprof output?
• Quiz Night 31 (March 2017): Why is this simple statement not updating using parallel DML? (The answer is the same even in 19.11.0.0)
• Quiz Night 30 (June 2016): What’s the clue that this plan came from 12c?
• Quiz Night 29 (Feb 2016): Create table t1, create table t2 as select * from t1 – why does t2 take much less space than t1?
• Quiz Night 28 (May 2015): A trick question and a nasty effect from rownum.
• Quiz Night 27 (Nov 2014): What’s the maximum (internal) arraysize used by Oracle for “insert as select”.
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