Tweak trace_sort code to show the merge order (number of active input

tapes) for each merge step.  This will give us some idea of how effective
the merge distribution algorithm is.

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index af0109fda653f5a2e31d4536a62451fc06744635..80a027d4a7a1e168fec069a354592f37fa9b9955 100644 (file)
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -91,7 +91,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/utils/sort/tuplesort.c,v 1.63 2006/03/07 19:06:50 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/sort/tuplesort.c,v 1.64 2006/03/08 16:59:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -296,6 +296,7 @@ struct Tuplesortstate
    int        *tp_runs;        /* # of real runs on each tape */
    int        *tp_dummy;       /* # of dummy runs for each tape (D[]) */
    int        *tp_tapenum;     /* Actual tape numbers (TAPE[]) */
+   int         activeTapes;    /* # of active input tapes in merge pass */
 
    /*
     * These variables are used after completion of sorting to keep track of
@@ -943,9 +944,15 @@ tuplesort_performsort(Tuplesortstate *state)
 
 #ifdef TRACE_SORT
    if (trace_sort)
-       elog(LOG, "performsort done%s: %s",
-            (state->status == TSS_FINALMERGE) ? " (except final merge)" : "",
-            pg_rusage_show(&state->ru_start));
+   {
+       if (state->status == TSS_FINALMERGE)
+           elog(LOG, "performsort done (except %d-way final merge): %s",
+                state->activeTapes,
+                pg_rusage_show(&state->ru_start));
+       else
+           elog(LOG, "performsort done: %s",
+                pg_rusage_show(&state->ru_start));
+   }
 #endif
 
    MemoryContextSwitchTo(oldcontext);
@@ -1566,7 +1573,7 @@ mergeonerun(Tuplesortstate *state)
 
 #ifdef TRACE_SORT
    if (trace_sort)
-       elog(LOG, "finished merge step: %s",
+       elog(LOG, "finished %d-way merge step: %s", state->activeTapes,
             pg_rusage_show(&state->ru_start));
 #endif
 }
@@ -1614,6 +1621,7 @@ beginmerge(Tuplesortstate *state)
            activeTapes++;
        }
    }
+   state->activeTapes = activeTapes;
 
    /*
     * Initialize space allocation to let each active input tape have an equal