Fix oversight in recent patch to support multiple read positions in

tuplestore: in READFILE state tuplestore_select_read_pointer must
save the current file seek position in the read pointer being
deactivated.

diff --git a/src/backend/utils/sort/tuplestore.c b/src/backend/utils/sort/tuplestore.c
index e127de3..b5bd67c 100644 (file)
--- a/src/backend/utils/sort/tuplestore.c
+++ b/src/backend/utils/sort/tuplestore.c
@@ -46,7 +46,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/sort/tuplestore.c,v 1.41 2008/10/04 21:56:54 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/sort/tuplestore.c,v 1.42 2008/10/07 00:05:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -434,7 +434,8 @@ tuplestore_end(Tuplestorestate *state)
 void
 tuplestore_select_read_pointer(Tuplestorestate *state, int ptr)
 {
-       TSReadPointer *readptr = &state->readptrs[ptr];
+       TSReadPointer *readptr;
+       TSReadPointer *oldptr;
 
        Assert(ptr >= 0 && ptr < state->readptrcount);
 
@@ -442,6 +443,9 @@ tuplestore_select_read_pointer(Tuplestorestate *state, int ptr)
        if (ptr == state->activeptr)
                return;
 
+       readptr = &state->readptrs[ptr];
+       oldptr = &state->readptrs[state->activeptr];
+
        switch (state->status)
        {
                case TSS_INMEM:
@@ -450,9 +454,18 @@ tuplestore_select_read_pointer(Tuplestorestate *state, int ptr)
                        break;
                case TSS_READFILE:
                        /*
+                        * First, save the current read position in the pointer about
+                        * to become inactive.
+                        */
+                       if (!oldptr->eof_reached)
+                               BufFileTell(state->myfile,
+                                                       &oldptr->file,
+                                                       &oldptr->offset);
+
+                       /*
                         * We have to make the temp file's seek position equal to the
-                        * logical position of the read pointer.  In eof_reached state,
-                        * that's the EOF, which we have available from the saved
+                        * logical position of the new read pointer.  In eof_reached
+                        * state, that's the EOF, which we have available from the saved
                         * write position.
                         */
                        if (readptr->eof_reached)