Rename tuplesort.c's SortTuple.tupindex field.

Rename the "tupindex" field from tuplesort.c's SortTuple struct to
"srctape", since it can only ever be used to store a source/input tape
number when merging external sort runs.  This has been the case since
commit 8b304b8b72b, which removed replacement selection sort from
tuplesort.c.

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index e96fa50ec5913e051bddeef9e579b7f72c3f1c4d..bda802b447f4d525c22f668bf4e70eaadb2ae195 100644 (file)
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -141,7 +141,8 @@ bool                optimize_bounded_sort = true;
  * which is a separate palloc chunk --- we assume it is just one chunk and
  * can be freed by a simple pfree() (except during merge, when we use a
  * simple slab allocator).  SortTuples also contain the tuple's first key
- * column in Datum/nullflag format, and an index integer.
+ * column in Datum/nullflag format, and a source/input tape number that
+ * tracks which tape each heap element/slot belongs to during merging.
  *
  * Storing the first key column lets us save heap_getattr or index_getattr
  * calls during tuple comparisons.  We could extract and save all the key
@@ -162,16 +163,13 @@ bool              optimize_bounded_sort = true;
  * either the same pointer as "tuple", or is an abbreviated key value as
  * described above.  Accordingly, "tuple" is always used in preference to
  * datum1 as the authoritative value for pass-by-reference cases.
- *
- * tupindex holds the input tape number that each tuple in the heap was read
- * from during merge passes.
  */
 typedef struct
 {
        void       *tuple;                      /* the tuple itself */
        Datum           datum1;                 /* value of first key column */
        bool            isnull1;                /* is first key column NULL? */
-       int                     tupindex;               /* see notes above */
+       int                     srctape;                /* source tape number */
 } SortTuple;
 
 /*
@@ -2093,7 +2091,7 @@ tuplesort_gettuple_common(Tuplesortstate *state, bool forward,
                         */
                        if (state->memtupcount > 0)
                        {
-                               int                     srcTape = state->memtuples[0].tupindex;
+                               int                     srcTape = state->memtuples[0].srctape;
                                SortTuple       newtup;
 
                                *stup = state->memtuples[0];
@@ -2124,7 +2122,7 @@ tuplesort_gettuple_common(Tuplesortstate *state, bool forward,
                                        LogicalTapeRewindForWrite(state->tapeset, srcTape);
                                        return true;
                                }
-                               newtup.tupindex = srcTape;
+                               newtup.srctape = srcTape;
                                tuplesort_heap_replace_top(state, &newtup);
                                return true;
                        }
@@ -2808,7 +2806,7 @@ mergeonerun(Tuplesortstate *state)
                SortTuple       stup;
 
                /* write the tuple to destTape */
-               srcTape = state->memtuples[0].tupindex;
+               srcTape = state->memtuples[0].srctape;
                WRITETUP(state, destTape, &state->memtuples[0]);
 
                /* recycle the slot of the tuple we just wrote out, for the next read */
@@ -2821,7 +2819,7 @@ mergeonerun(Tuplesortstate *state)
                 */
                if (mergereadnext(state, srcTape, &stup))
                {
-                       stup.tupindex = srcTape;
+                       stup.srctape = srcTape;
                        tuplesort_heap_replace_top(state, &stup);
                }
                else
@@ -2886,7 +2884,7 @@ beginmerge(Tuplesortstate *state)
 
                if (mergereadnext(state, srcTape, &tup))
                {
-                       tup.tupindex = srcTape;
+                       tup.srctape = srcTape;
                        tuplesort_heap_insert(state, &tup);
                }
        }