Startup

• main: `postmaster' vs. `postgres'
• postmaster -> PostmasterMain()
• Parse command line options
• ServerLoop()
• BackendStartup()
• DoBackend() ->authentication ->postgres
• postgres -> PostgresMain()
• BaseInit()
• PostgresInit()
• Begin FE/BE query level interaction
• Look for `Q' - Query
• If received, pg_exec_query_string()
• pg_parse_query() - build list of node trees representing query
• pg_analyze_and_rewrite() - parse to interal data respresentation and rewrite if necessary
• if node is CMD_UTILITY ->ProcessUtility()
• else pg_plan_query()
• planner-> subquery_planner()
• optimise: any queries in join tree; preprocess join tree (constants, etc); preprocess target list; build top level grouping/aggregate plans
• final planning: SS_finalize_plan()
• ProcessQuery() -> ExecutorRun() -> ExecutePlan() -> ExecProcNode()
• Determine plan type: seqscan, index scan, cursor...
• Read out a slot (result tuple)
• Determine query type: CMD_INSERT, CMD_DELETE, etc and update tuple
• continue back end looping

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