Sequential Scan Callstack (Postgres Coderef)

개요 §

• 본 작물에서는 PostgreSQL 에서 sequential scan (가령 SELECT * FROM table;) 을 했을때의 function call stack 을 정리해 본다.

Stack §

• 우선 공통 로직 을 처리한 다음, Executor, Access Method Call Path 부터 시작한다.

Executor, Access Method Call Path §

• ExecSeqScan()
  • ExecScan()
    • ExecScanFetch()
      • SeqNext()
        • table_beginscan()
          • heap_beginscan()
        • table_scan_getnextslot()
          • heap_getnextslot()
            • heapgettup_pagemode()
              • heapgettup_continue_page()
              • heap_fetch_next_buffer()
                • Call path: read_stream_next_buffer()

read_stream_next_buffer() Call Path §

• read_stream_next_buffer()
  • Call Path: read_stream_get_block()
  • StartReadBuffer()
    • Call Path: StartReadBuffersImpl()
  • Call Path: read_stream_look_ahead()
  • WaitReadBuffers()
    • WaitReadBuffersCanStartIO()
    • smgrreadv()
      • mdreadv()
        • FileReadV()
  • Call Path: read_stream_look_ahead()

StartReadBuffersImpl() Call Path §

• StartReadBuffersImpl()
  • PinBufferForBlock()
    • BufferAlloc()
  • smgrprefetch()
    • mdprefetch()
      • FilePrefetch()

read_stream_get_block() Call Path §

• read_stream_get_block()
  • heap_scan_stream_read_next_serial()
    • heapgettup_initial_block()
    • heapgettup_advance_block()

read_stream_look_ahead() Call Path §

• read_stream_look_ahead()
  • Call Path: read_stream_get_block()
  • read_stream_start_pending_read()
    • StartReadBuffers()
      • Call Path: StartReadBuffersImpl()