Infrastructure Catalogue

This is a list of articles I’ve written that get a little heavily into technical details and won’t necessarily be very helpful to the typical DBA or developer. Each entry has a date stamp and a short note of the contents. The articles are generally listed most-recent first.

• Dumping redo (Sept 2022): a convenient method for minimising the redo you need to dump when testing a feature.
• Shrinking Indexes (Sept 2022): A lesson in comparing workloads – in this case index coalese vs. shrink space (with or without compact).
• Drop Partition (Aug 2022): the mechanics and cost of deferred global index maintenance
• ORA-00054 pt.1 (July 2022): Trouble-shooting with errorstack and ksq trace
  • ORA-00054 pt.2 (July 2022): Trouble-shooting with systemstate trace
• Why “lag() ignore nulls” is slow (May 2022): and how to work around the problem in some cases.
• dbms_redefinition defect (May 2022): using copy_table_dependencies() can produce metadata inconsistencies.
• Long v$ definitions (Mar 2022): Some definitions in v$fixed_view_definition are too long for the view. A workaround.
• X$ row sizes (Mar 2022): Simple script to get some clue about rows in x$ structures
• V$ cascade (Mar 2022): Why does is v$ a synonym for v_$ which is a view on v$
• Digging into x$ (Mar 2022): preliminary investigation of x$ information
• Session Count issue (Mar 2022): v$session, v$resource_limit and v$sysmetric don’t agree – digging in to x$
• Data Defaults (Feb 2021): a quirky little detail about how column defaults can be stored (and a point in favour of “commas at the ends of lines”).
• Pivot Cosmetics (Feb 2021): a minor change in the SQL*Plus output for a pivot that may require format updates in your code.
• Supplemental logging mess (Jan 2021): you need to be a little careful when you add supplemental logging clauses to a table.
• Check Constraints (Jan 2021): an odd difference in locking and waiting between disabling and enabling constraints.
• Naming side-effects (Dec 2020): How an upgrade that allows longer object names could break existing code.
• Dates and formats (Dec 2020): It’s important to use date datatypes, and check for type-conversion threats.
• Java Names upgrade (Dec 2020): how an upgrade from 12c to 19c caused an error in “home-grown” auditing.
• Row Sizes – pt.3 (Nov 2020): a little hackery to report the relative frequency of nulls in each column of a table.
  • Row sizes – pt2 (Oct 2012): a little hackery to generate code to show the patterns of Nulls in the rows of a table.
  • Row sizes – pt1 (Sep 2012): a little hacker to generate a “histogram” showing the distribution of row sizes in a table.
• Querying v$session (Oct 2019): a performance threat for large systems
• What’s my SID (Oct 2019): several ways of getting the SID (and some for the serial#)
• Dumping redo (June 2019): includes examples of how to be selective in dumping (online and archived) redo log records.
• Redo Op Codes (July 2017): my personal reference for translating redo op codes.
• Unpivot mechanics (June 2017): what does Oracle do internally to handle an unpivot?
• Optimising statspack (Oct 2016): some data dictionary / internal queries really do need good stats to avoid performance disasters.
• v$lock efficiency (May 2013): the benefit of collecting stats on individual x$ structures
• Hint error (Feb 2012): why is v$sql_shared_memory returning no data?
• Real-time Block Recovery (Dec 2010): How Oracle may handle blocks in the buffer cache that appear to have been corrupted
• Lock Modes (June 2010): my personal reference for translating numeric lock modes.
• PGA Memory (June 2009): checking process memory and process memory detail.
• Oracle Pipes (Jan 2009): What’s currently inside a pipe created by dbms_pipe.