High consumns memory

I have a software developed in Delphi as a Windows Service, but, i don't know why, it consumns an unexpected large system memory (1.3g).

The service access PostgresSQL by ODBC driver (psqlodbc_08_03_0400) and it consist simply of a loop calling a procedure PL/PGSQL. How to discover what is causing or why this high memory usage ? What objects are being used on this session ?

Software developed in Delphi 7 as a windows service.

PostgresSQL 8.3.6 Database with PostGis extension

Server p52a

S.O.: Red Hat Enterprise Linux AS release 4 (Nahant Update 1)

      linux 2.6.9-11.EL #1 SMP ppc64 ppc64 ppc64 GNU/Linux

S.O. information

 top - 11:39:15 up 6 days, 19:15,  1 user,  load average: 2.15, 2.02, 1.86

Tasks: 127 total,   1 running, 126 sleeping,   0 stopped,   0 zombie

Cpu(s):  9.5% us,  2.6% sy,  0.0% ni, 71.2% id, 16.3% wa,  0.1% hi,  0.2% si

Mem:   4107392k total,  4101520k used,     5872k free,    17708k buffers

Swap:  2031608k total,      244k used,  2031364k free,  3091708k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND

32662 postgres  16   0 1317m 1.3g 516m D 52.5 32.1 349:57.48 postgres

 8953 postgres  17   0  548m 482m 479m S 33.5 12.0   2:50.09 postgres

 1944 postgres  16   0  550m 520m 516m S  7.3 13.0 165:30.47 postgres

32659 postgres  15   0  544m 516m 514m S  1.3 12.9  16:42.60 postgres

 1935 postgres  15   0  543m 514m 513m S  1.0 12.8  15:15.56 postgres

postgresql.conf information:

              name               |                        setting       | unit

---------------------------------+--------------------------------------+------

 archive_command                 | wal_archive_command.sh %p %f         |

 archive_mode                    | on                                   |

 autovacuum_analyze_scale_factor | 0.4                                  |

 autovacuum_analyze_threshold    | 500                                  |

 autovacuum_vacuum_threshold     | 1000                                 |

 checkpoint_segments             | 15                                   |

 checkpoint_timeout              | 1800                                 | s

 DateStyle                       | ISO, DMY                             |

 default_statistics_target       | 50                                   |

 effective_cache_size            | 249600                               | 8kB

 fsync                           | on                                   |

 lc_monetary                     | en_US.UTF-8                          |

 lc_numeric                      | en_US.UTF-8                          |

 lc_time                         | en_US.UTF-8                          |

 listen_addresses                | *                                    |

 log_autovacuum_min_duration     | 0                                    | ms

 log_checkpoints                 | on                                   |

 log_destination                 | stderr                               |

 log_directory                   | /p01/log                             |

 log_filename                    | postgresql-%Y-%m-%d_%H%M%S.log       |

 log_line_prefix                 | %t [%p]: [%l-1]                      |

 log_lock_waits                  | on                                   |

 log_min_duration_statement      | 250                                  | ms

 log_min_error_statement         | error                                |

 log_rotation_age                | 1440                                 | min

 log_rotation_size               | 20480                                | kB

 log_temp_files                  | 10240                                | kB

 logging_collector               | on                                   |

 maintenance_work_mem            | 409600                               | kB

 max_connections                 | 100                                  |

 max_fsm_pages                   | 3458000                              |

 shared_buffers                  | 64000                                | 8kB

 tcp_keepalives_idle             | 0                                    | s

 wal_buffers                     | 100                                  | 8kB

 work_mem                        | 5120                                 | kB