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What is EXPLAIN?

• rsynnott 7y ago
  SQL command to show how a database engine will execute a given query. I wouldn't necessarily expect a CTO to know about it, to be honest, unless their background was somewhat database-y.
• teddyh 7y ago
  It’s not in standard SQL, but is present in most SQL implementations: https://www.postgresql.org/docs/current/sql-explain.html https://www.postgresql.org/docs/current/sql-explain.html https://www.sqlite.org/lang_explain.html https://www.sqlite.org/lang_explain.html https://mariadb.com/kb/en/explain/ https://mariadb.com/kb/en/explain/
• shagie 7y ago
  A tool for looking at how a query is run and where it may be slow. https://docs.oracle.com/cd/B19306_01/server.102/b14211/ex_plan.htm#i3305 https://docs.oracle.com/cd/B19306_01/server.102/b14211/ex_pl... https://dev.mysql.com/doc/refman/5.7/en/explain.html https://dev.mysql.com/doc/refman/5.7/en/explain.html https://www.postgresql.org/docs/current/sql-explain.html https://www.postgresql.org/docs/current/sql-explain.html https://docs.microsoft.com/en-us/sql/t-sql/queries/explain-transact-sql?view=azure-sqldw-latest https://docs.microsoft.com/en-us/sql/t-sql/queries/explain-t...