Data Corruptions (How to delete a corrupted row?)

Hello,

I am running PostgreSQL v7.2.1 under RedHat 7.3.

I have a database of three or four tables with several
million records.

I have been getting minor (repairable) data corruption on a
regular basis.  This is where some field's contents get
partially changed to funny characters.

Until yesterday, I was able to access those rows and delete
those records.

The data corruption has gotten so bad that I no longer can
access certain records. Therefore it fails most of my
production operations.  Also the vacuum keeps failing now.

Vacuum Error Message:
----------------------------------------------
NOTICE:  Analyzing pg_rewrite
NOTICE:  --Relation urls--
ERROR:  XLogFlush: request 16/E6B686EC is not satisfied ---

flushed only to 16/E6B680E4
vacuumdb: vacuum  xxxxxx failed
----------------------------------------------


PG_DUMP Error Message
----------------------------------------------
pg_dump xxxxx > backup/xxxxxx-072102.sql
pg_dump: ERROR:  MemoryContextAlloc: invalid request size
1919435556
pg_dump: lost synchronization with server, resetting
connection
pg_dump: SQL command to dump the contents of table "test"
failed: PQendcopy() failed.
pg_dump: Error message from server: pg_dump: The command
was: COPY "docs" TO stdout;
----------------------------------------------

As far as the size of my database is concerned, it is well
below 1Gig.

I seriously considering downgrading to lower release of
postgres.

Thanks,
Massoud

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