Use a cursor for fetching data in -d or -D mode, so that pg_dump doesn't

run out of memory with large tables in these modes.  Patch from
Martijn van Oosterhout.

diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 6085c241f4035b8d0148056ee9b830d474541447..abed81cf825add76ce71a0de521299ef314c7dc0 100644 (file)
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -22,7 +22,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/bin/pg_dump/pg_dump.c,v 1.226 2001/08/27 01:09:59 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/bin/pg_dump/pg_dump.c,v 1.227 2001/08/27 20:33:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -400,77 +400,105 @@ dumpClasses_dumpData(Archive *fout, char *oid, void *dctxv)
 
        if (fout->remoteVersion >= 70100)
        {
-               appendPQExpBuffer(q, "SELECT * FROM ONLY %s", fmtId(classname, force_quotes));
+               appendPQExpBuffer(q, "DECLARE _pg_dump_cursor CURSOR FOR SELECT * FROM ONLY %s", fmtId(classname, force_quotes));
        } else {
-               appendPQExpBuffer(q, "SELECT * FROM %s", fmtId(classname, force_quotes));
+               appendPQExpBuffer(q, "DECLARE _pg_dump_cursor CURSOR FOR SELECT * FROM %s", fmtId(classname, force_quotes));
        }
 
        res = PQexec(g_conn, q->data);
        if (!res ||
-               PQresultStatus(res) != PGRES_TUPLES_OK)
+               PQresultStatus(res) != PGRES_COMMAND_OK)
        {
                write_msg(NULL, "dumpClasses(): SQL command failed\n");
                write_msg(NULL, "Error message from server: %s", PQerrorMessage(g_conn));
                write_msg(NULL, "The command was: %s\n", q->data);
                exit_nicely();
        }
-       for (tuple = 0; tuple < PQntuples(res); tuple++)
-       {
-               archprintf(fout, "INSERT INTO %s ", fmtId(classname, force_quotes));
-               if (attrNames == true)
+       
+       do {
+               PQclear(res);
+
+               res = PQexec(g_conn, "FETCH 100 FROM _pg_dump_cursor");
+               if (!res ||
+                       PQresultStatus(res) != PGRES_TUPLES_OK)
                {
-                       resetPQExpBuffer(q);
-                       appendPQExpBuffer(q, "(");
-                       for (field = 0; field < PQnfields(res); field++)
-                       {
-                               if (field > 0)
-                                       appendPQExpBuffer(q, ",");
-                               appendPQExpBuffer(q, fmtId(PQfname(res, field), force_quotes));
-                       }
-                       appendPQExpBuffer(q, ") ");
-                       archprintf(fout, "%s", q->data);
+                       write_msg(NULL, "dumpClasses(): SQL command failed\n");
+                       write_msg(NULL, "Error message from server: %s", PQerrorMessage(g_conn));
+                       write_msg(NULL, "The command was: FETCH 100 FROM _pg_dump_cursor\n");
+                       exit_nicely();
                }
-               archprintf(fout, "VALUES (");
-               for (field = 0; field < PQnfields(res); field++)
+
+               for (tuple = 0; tuple < PQntuples(res); tuple++)
                {
-                       if (field > 0)
-                               archprintf(fout, ",");
-                       if (PQgetisnull(res, tuple, field))
+                       archprintf(fout, "INSERT INTO %s ", fmtId(classname, force_quotes));
+                       if (attrNames == true)
                        {
-                               archprintf(fout, "NULL");
-                               continue;
+                               resetPQExpBuffer(q);
+                               appendPQExpBuffer(q, "(");
+                               for (field = 0; field < PQnfields(res); field++)
+                               {
+                                       if (field > 0)
+                                               appendPQExpBuffer(q, ",");
+                                       appendPQExpBuffer(q, fmtId(PQfname(res, field), force_quotes));
+                               }
+                               appendPQExpBuffer(q, ") ");
+                               archprintf(fout, "%s", q->data);
                        }
-                       switch (PQftype(res, field))
+                       archprintf(fout, "VALUES (");
+                       for (field = 0; field < PQnfields(res); field++)
                        {
-                               case INT2OID:
-                               case INT4OID:
-                               case OIDOID:    /* int types */
-                               case FLOAT4OID:
-                               case FLOAT8OID:/* float types */
-                                       /* These types are printed without quotes */
-                                       archprintf(fout, "%s",
-                                                          PQgetvalue(res, tuple, field));
-                                       break;
-                               case BITOID:
-                               case VARBITOID:
-                                       archprintf(fout, "B'%s'",
-                                                          PQgetvalue(res, tuple, field));
-                                       break;
-                               default:
-
-                                       /*
-                                        * All other types are printed as string literals,
-                                        * with appropriate escaping of special characters.
-                                        */
-                                       resetPQExpBuffer(q);
-                                       formatStringLiteral(q, PQgetvalue(res, tuple, field), CONV_ALL);
-                                       archprintf(fout, "%s", q->data);
-                                       break;
+                               if (field > 0)
+                                       archprintf(fout, ",");
+                               if (PQgetisnull(res, tuple, field))
+                               {
+                                       archprintf(fout, "NULL");
+                                       continue;
+                               }
+                               switch (PQftype(res, field))
+                               {
+                                       case INT2OID:
+                                       case INT4OID:
+                                       case OIDOID:    /* int types */
+                                       case FLOAT4OID:
+                                       case FLOAT8OID:/* float types */
+                                               /* These types are printed without quotes */
+                                               archprintf(fout, "%s",
+                                                                  PQgetvalue(res, tuple, field));
+                                               break;
+                                       case BITOID:
+                                       case VARBITOID:
+                                               archprintf(fout, "B'%s'",
+                                                                  PQgetvalue(res, tuple, field));
+                                               break;
+                                       default:
+       
+                                               /*
+                                                * All other types are printed as string literals,
+                                                * with appropriate escaping of special characters.
+                                                */
+                                               resetPQExpBuffer(q);
+                                               formatStringLiteral(q, PQgetvalue(res, tuple, field), CONV_ALL);
+                                               archprintf(fout, "%s", q->data);
+                                               break;
+                               }
                        }
+                       archprintf(fout, ");\n");
                }
-               archprintf(fout, ");\n");
+
+       } while( PQntuples(res) > 0 );
+       PQclear(res);
+
+       res = PQexec(g_conn, "CLOSE _pg_dump_cursor");
+       if (!res ||
+               PQresultStatus(res) != PGRES_COMMAND_OK)
+       {
+               write_msg(NULL, "dumpClasses(): SQL command failed\n");
+               write_msg(NULL, "Error message from server: %s", PQerrorMessage(g_conn));
+               write_msg(NULL, "The command was: CLOSE _pg_dump_cursor\n");
+               exit_nicely();
        }
        PQclear(res);
+
        destroyPQExpBuffer(q);
        return 1;
 }