Apartir da
versão 11g do Oracle é possível acessar as mensagens do “alert.log” da base de
dados sem a necessidade de acessar o arquivo através do sistema operacional.
Em
instalações “default” o arquivo “alert.log” fica localizado em : [$ORACLE_BASE/diag/rdbms/{DB_UNIQUE_NAME}/{SID}/alert/log_XX.xml].
Onde:
  
ORACLE_BASE
 | 
  
  
Diretório base da instalação do software Oracle;
 | 
 
  
DB_UNIQUE_NAME
 | 
  
  
Nome do banco de dados do banco;
 | 
 
  
SID
 | 
  
  
Nome da instância no servidor (em configurações RAC esse nome varia);
 | 
 
  
XX
 | 
  
  
Nome da instância para identificar o nome do arquivo de “alert.log”.
 | 
 
Para isso basta acessar as informações contidas na visão X$DBGALERTEXT, abaixo pode-se ver as colunas desta visão.
SQL> desc X$DBGALERTEXT
 Name                                     
Null?    Type
 -----------------------------------------
-------- ----------------------------
 ADDR                                              
RAW(8)
 INDX                                              
NUMBER
 INST_ID                                           
NUMBER
 ORIGINATING_TIMESTAMP                              TIMESTAMP(3) WITH
TIME ZONE
 NORMALIZED_TIMESTAMP                               TIMESTAMP(3)
WITH TIME ZONE
 ORGANIZATION_ID                                   
VARCHAR2(64)
 COMPONENT_ID                                       VARCHAR2(64)
 HOST_ID                                           
VARCHAR2(64)
 HOST_ADDRESS                                      
VARCHAR2(46)
 MESSAGE_TYPE                                       NUMBER
 MESSAGE_LEVEL                                      NUMBER
 MESSAGE_ID                                        
VARCHAR2(64)
 MESSAGE_GROUP                                     
VARCHAR2(64)
 CLIENT_ID                                         
VARCHAR2(64)
 MODULE_ID                                         
VARCHAR2(64)
 PROCESS_ID                                        
VARCHAR2(32)
 THREAD_ID                                         
VARCHAR2(64)
 USER_ID                                           
VARCHAR2(64)
 INSTANCE_ID                                       
VARCHAR2(64)
 DETAILED_LOCATION                                  VARCHAR2(160)
 PROBLEM_KEY                                       
VARCHAR2(64)
 UPSTREAM_COMP_ID                                   VARCHAR2(100)
 DOWNSTREAM_COMP_ID                                 VARCHAR2(100)
 EXECUTION_CONTEXT_ID                               VARCHAR2(100)
 EXECUTION_CONTEXT_SEQUENCE                         NUMBER
 ERROR_INSTANCE_ID                                  NUMBER
 ERROR_INSTANCE_SEQUENCE                            NUMBER
 VERSION                                           
NUMBER
 MESSAGE_TEXT                                      
VARCHAR2(2048)
 MESSAGE_ARGUMENTS                                  VARCHAR2(128)
 SUPPLEMENTAL_ATTRIBUTES                            VARCHAR2(128)
 SUPPLEMENTAL_DETAILS                               VARCHAR2(128)
 PARTITION                                         
NUMBER
 RECORD_ID                                          NUMBER
Para verificar as
informações de alerta do banco pode-se executar a consulta abaixo:
SET LINESIZE 160 PAGESIZE 200
COL ORIGINATING_TIMESTAMP FOR A20 HEAD DATA
COL ORIGINATING_TIMESTAMP FOR A20 HEAD DATA
COL MESSAGE_TEXT FOR A120 HEAD
MENSAGEM
SELECT TO_CHAR(ORIGINATING_TIMESTAMP,'DD.MM.YYYY HH24:MI:SS') DATA,
MESSAGE_TEXT
FROM X$DBGALERTEXT;
SELECT TO_CHAR(ORIGINATING_TIMESTAMP,'DD.MM.YYYY HH24:MI:SS') DATA,
MESSAGE_TEXT
FROM X$DBGALERTEXT;
Caso queira verificar somente as mensagens de erro
pode-se utilizar a consulta abaixo:
SET LINESIZE 160 PAGESIZE 200
COL ORIGINATING_TIMESTAMP FOR A20 HEAD DATA
COL ORIGINATING_TIMESTAMP FOR A20 HEAD DATA
COL MESSAGE_TEXT FOR A120 HEAD MENSAGEM
SELECT
DISTINCT TO_CHAR(ORIGINATING_TIMESTAMP,'DD.MM.YYYY HH24:MI:SS') DATA,
                MESSAGE_TEXT 
  FROM X$DBGALERTEXT
 WHERE ORIGINATING_TIMESTAMP > SYSDATE-2
   AND (MESSAGE_TEXT = 'ORA-00600' OR
MESSAGE_TEXT LIKE '%FATAL%');
Referência: Oracle® Database Administrator´s
Guide 11gR2 (11.2) 
MSc.
Rubens Oliveira
DBA Oracle Consultor