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Quiz 1

Results summary on Webcms3.

Q1. select * from R, S where R.x=S.x and R.y = 2 and S.w > 4;

  • minimise size of intermediate results; do Sel before Join
Q2. names of file for tables in the public schema
  • pg_class.relkind='r' and pg_namespace.nspname='public'
Q3. contents of data/base/.../ vs data/global/
  • some catalog tables are server-global, others are database-specific
  • e.g. pg_database (server-global) vs pg_class (db-specific)