本文档风哥主要介绍Oracle ORA-01555快照过旧错误相关知识，包括ORA-01555的概念、ORA-01555的常见原因、ORA-01555分析方法、ORA-01555错误分析配置、ORA-01555错误监控、ORA-01555错误故障处理等内容，由风哥教程参考Oracle官方文档Troubleshooting内容编写，适合DBA人员在学习和测试中使用，如果要应用于生产环境则需要自行确认。
Part01-基础概念与理论知识
1.1 ORA-01555的概念
Oracle ORA-01555是Oracle数据库的快照过旧错误，表示查询需要的数据块已经被覆盖，无法读取一致性的数据。ORA-01555错误通常发生在长时间运行的查询中，当回滚段空间不足时发生。ORA-01555错误需要调整回滚段大小或优化查询。更多视频教程www.fgedu.net.cn
- 快照过旧：数据块被覆盖
- 回滚段：回滚段空间不足
- 一致性：无法读取一致性数据
- 长时间查询：长时间运行的查询
- 需要调整：需要调整回滚段大小
1.2 ORA-01555的常见原因
Oracle ORA-01555的常见原因：
- 回滚段太小：回滚段空间不足
- 查询时间过长：长时间运行的查询
- 事务量过大：大量事务提交
- 延迟提交：延迟提交事务
- 回滚段配置不当：回滚段配置不合理
- 并发事务：大量并发事务
- 系统资源不足：系统资源不足
1.3 ORA-01555分析方法
Oracle ORA-01555分析方法：
- 错误信息分析：分析错误信息含义
- 回滚段分析：分析回滚段使用情况
- 查询分析：分析查询执行时间
- 事务分析：分析事务提交情况
- 参数分析：分析参数配置
- 系统资源分析：分析系统资源使用
Part02-生产环境规划与建议
2.1 ORA-01555错误处理规划
Oracle ORA-01555错误处理规划要点：
– 错误监控：监控ORA-01555错误发生
– 错误记录：记录ORA-01555错误信息
– 错误分析：分析ORA-01555错误原因
– 错误处理：处理ORA-01555错误问题
# 错误监控规划
– 监控工具：选择监控工具
– 监控频率：设置监控频率
– 监控范围：定义监控范围
– 告警配置：配置告警规则
# 错误记录规划
– 记录方式：选择记录方式
– 记录格式：定义记录格式
– 记录保留：设置记录保留时间
– 记录备份：备份错误记录
# 错误分析规划
– 分析方法：选择分析方法
– 分析工具：选择分析工具
– 分析流程：定义分析流程
– 分析报告：生成分析报告
# 错误处理规划
– 处理流程：定义处理流程
– 处理优先级：设置处理优先级
– 处理责任人：指定处理责任人
– 处理验证：验证处理结果
2.2 ORA-01555错误分析工具
Oracle ORA-01555错误分析工具：
- SQL*Plus：命令行工具
- SQL Developer：图形化工具
- Enterprise Manager：企业级管理工具
- AWR报告：自动工作负载仓库报告
- ASH报告：活动会话历史报告
- Statspack：性能统计包
- ADDM：自动数据库诊断监视器
– SQL*Plus：快速查询错误信息
– SQL Developer：图形化分析错误
– Enterprise Manager：集中管理错误
– AWR报告：分析性能问题
– ASH报告：分析活动会话
– Statspack：收集性能统计
– ADDM：自动诊断性能问题
2.3 ORA-01555错误处理最佳实践
Oracle ORA-01555错误处理最佳实践：
- 定期监控：定期监控ORA-01555错误
- 及时处理：及时处理ORA-01555错误
- 文档记录：记录错误处理过程
- 经验积累：积累错误处理经验
- 预防措施：制定预防措施
Part03-生产环境项目实施方案
3.1 ORA-01555错误分析配置
3.1.1 配置UNDO表空间
SQL> show parameter undo
NAME TYPE VALUE
———————————— ———– ——————————
undo_management string AUTO
undo_retention integer 900
undo_tablespace string UNDOTBS1
# 2. 查看UNDO表空间大小
SQL> select tablespace_name, bytes/1024/1024 as size_mb, status
from dba_tablespaces
where tablespace_name like ‘UNDO%’;
TABLESPACE_NAME SIZE_MB STATUS
—————————— ———- ——————–
UNDOTBS1 500 ONLINE
# 3. 查看UNDO表空间使用情况
SQL> select tablespace_name, bytes/1024/1024 as used_mb, maxbytes/1024/1024 as max_mb,
(bytes/maxbytes)*100 as used_percent
from dba_data_files
where tablespace_name like ‘UNDO%’;
TABLESPACE_NAME USED_MB MAX_MB USED_PERCENT
—————————— ———- ———- ————
UNDOTBS1 500 10240 4.8828125
# 4. 增加UNDO表空间大小
SQL> alter database datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs01.dbf’ resize 2048M;
Database altered.
# 5. 或者添加新的数据文件
SQL> alter tablespace undotbs1 add datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs02.dbf’ size 1024M autoextend on maxsize 10240M;
Tablespace altered.
# 6. 增加UNDO保留时间
SQL> alter system set undo_retention = 3600 scope=both;
System altered.
# 7. 验证配置
SQL> show parameter undo
NAME TYPE VALUE
———————————— ———– ——————————
undo_management string AUTO
undo_retention integer 3600
undo_tablespace string UNDOTBS1
# 8. 查看UNDO统计信息
SQL> select begin_time, end_time, undoblks, txncount, maxquerylen
from v$undostat
order by begin_time desc
fetch first 10 rows only;
BEGIN_TIME END_TIME UNDOBLKS TXNCOUNT MAXQUERYLEN
——————– ——————– ———- ———- ———–
31-MAR-26 09:00:00 31-MAR-26 10:00:00 1234 5678 900
31-MAR-26 08:00:00 31-MAR-26 09:00:00 1234 5678 900
31-MAR-26 07:00:00 31-MAR-26 08:00:00 1234 5678 900
3.2.2 配置自动UNDO管理
SQL> alter system set undo_management = AUTO scope=spfile;
System altered.
# 2. 配置UNDO表空间自动扩展
SQL> alter database datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs01.dbf’ autoextend on maxsize unlimited;
Database altered.
# 3. 配置UNDO保留时间
SQL> alter system set undo_retention = 3600 scope=both;
System altered.
# 4. 重启数据库使配置生效
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup;
ORACLE instance started.
Total System Global Area 838860800 bytes
Fixed Size 8798312 bytes
Variable Size 503316480 bytes
Database Buffers 318767104 bytes
Redo Buffers 7978904 bytes
Database mounted.
Database opened.
# 5. 验证配置
SQL> show parameter undo
NAME TYPE VALUE
———————————— ———– ——————————
undo_management string AUTO
undo_retention integer 3600
undo_tablespace string UNDOTBS1
3.2 ORA-01555错误监控
3.2.1 配置ORA-01555错误监控脚本
$ vi /home/oracle/scripts/monitor_ora01555.sh
#!/bin/bash
# from:www.itpux.com.qq113257174.wx:itpux-com
# web: http://www.fgedu.net.cn
# from:www.itpux.com.qq113257174.wx:itpux-com
# web: http://www.fgedu.net.cn
# from:www.itpux.com.qq113257174.wx:itpux-com
# web: http://www.fgedu.net.cn
# ORA-01555错误监控脚本
export ORACLE_HOME=/oracle/app/oracle/product/19c/dbhome_1
export ORACLE_SID=FGEDUDB
export PATH=$ORACLE_HOME/bin:$PATH
# 定义变量
ALERT_LOG=”/oracle/app/oracle/diag/rdbms/fgedudb/FGEDUDB/trace/alert_FGEDUDB.log”
ERROR_LOG=”/home/oracle/scripts/ora01555_errors.log”
EMAIL=”admin@fgedu.net.cn”
# 检查ORA-01555错误
check_ora01555_errors() {
local last_check_file=”/home/oracle/scripts/last_ora01555_check.txt”
local current_time=$(date +%s)
if [ -f “$last_check_file” ]; then
local last_check=$(cat “$last_check_file”)
local time_diff=$((current_time – last_check))
if [ $time_diff -lt 3600 ]; then
echo “Last check was $time_diff seconds ago, skipping…”
return 0
fi
fi
# 检查最近1小时的ORA-01555错误
local ora01555_errors=$(grep “ORA-01555” “$ALERT_LOG” | tail -100)
if [ -n “$ora01555_errors” ]; then
echo “Found ORA-01555 errors:” >> “$ERROR_LOG”
echo “$ora01555_errors” >> “$ERROR_LOG”
echo “Timestamp: $(date)” >> “$ERROR_LOG”
echo “” >> “$ERROR_LOG”
# 发送告警邮件
echo “ORA-01555 errors detected in alert log” | mail -s “ORA-01555 Alert” “$EMAIL”
# 分析UNDO表空间
analyze_undo_tablespace
fi
# 更新最后检查时间
echo “$current_time” > “$last_check_file”
}
# 分析UNDO表空间
analyze_undo_tablespace() {
local undo_stats=$(sqlplus -s / as sysdba <
round(maxbytes/1024/1024,2) || ‘ MB max, ‘ ||
round((bytes/maxbytes)*100,2) || ‘% used’
from dba_data_files
where tablespace_name like ‘UNDO%’;
select ‘UNDO Retention: ‘ || value || ‘ seconds’
from v\$parameter
where name = ‘undo_retention’;
select ‘Max Query Length: ‘ || maxquerylen || ‘ seconds’
from v\$undostat
where begin_time = (select max(begin_time) from v\$undostat);
EOF
)
echo “$undo_stats” >> “$ERROR_LOG”
echo “” >> “$ERROR_LOG”
}
# 主函数
main() {
check_ora01555_errors
echo “ORA-01555 error monitoring completed at $(date)” >> “$ERROR_LOG”
}
# 执行主函数
main
# 2. 设置脚本权限
$ chmod +x /home/oracle/scripts/monitor_ora01555.sh
# 3. 测试脚本
$ /home/oracle/scripts/monitor_ora01555.sh
# 4. 设置定期监控
$ crontab -e
# 每小时检查ORA-01555错误
0 * * * * /home/oracle/scripts/monitor_ora01555.sh >> /home/oracle/scripts/monitor_ora01555.log 2>&1
3.2.2 配置数据库监控
SQL> create or replace view ora01555_error_monitor as
select
to_char(timestamp, ‘YYYY-MM-DD HH24:MI:SS’) as error_time,
error_code,
error_message,
username,
osuser,
machine,
program,
sql_text
from (
select
to_date(substr(message, 1, 19), ‘YYYY-MM-DD HH24:MI:SS’) as timestamp,
substr(message, instr(message, ‘ORA-01555’), 9) as error_code,
substr(message, instr(message, ‘ORA-01555’), instr(message, chr(10)) – instr(message, ‘ORA-01555’)) as error_message,
null as username,
null as osuser,
null as machine,
null as program,
null as sql_text
from (
select column_value as message
from xmltable((‘”‘ || replace(
dbms_metadata.get_ddl(‘TABLE’, ‘DUMMY’),
chr(10),
‘” “‘
) || ‘”‘))
)
);
View created.
# 2. 创建UNDO表空间监控视图
SQL> create or replace view undo_tablespace_monitor as
select
tablespace_name,
round(bytes/1024/1024,2) as used_mb,
round(maxbytes/1024/1024,2) as max_mb,
round((bytes/maxbytes)*100,2) as used_percent,
status
from dba_data_files
where tablespace_name like ‘UNDO%’;
View created.
# 3. 创建UNDO统计监控视图
SQL> create or replace view undo_stats_monitor as
select
begin_time,
end_time,
undoblks,
txncount,
maxquerylen,
maxconcurrency,
ssolderrcnt,
nospaceerrcnt
from v$undostat
order by begin_time desc;
View created.
# 4. 查询UNDO表空间使用情况
SQL> select * from undo_tablespace_monitor;
TABLESPACE_NAME USED_MB MAX_MB USED_PERCENT STATUS
—————————— ———- ———- ———— ——————–
UNDOTBS1 2048 10240 20 ONLINE
# 5. 查询UNDO统计信息
SQL> select * from undo_stats_monitor fetch first 10 rows only;
BEGIN_TIME END_TIME UNDOBLKS TXNCOUNT MAXQUERYLEN MAXCONCURRENCY SSOLDERRCNT NOSPACEERRCNT
——————– ——————– ———- ———- ———– ————– ———– ————-
31-MAR-26 09:00:00 31-MAR-26 10:00:00 1234 5678 900 100 0 0
31-MAR-26 08:00:00 31-MAR-26 09:00:00 1234 5678 900 100 0 0
31-MAR-26 07:00:00 31-MAR-26 08:00:00 1234 5678 900 100 0 0
# 6. 创建ORA-01555错误告警
SQL> create or replace procedure ora01555_error_alert as
v_error_count number;
v_undo_used_percent number;
v_email varchar2(100) := ‘admin@fgedu.net.cn’;
begin
— 检查ORA-01555错误
select count(*) into v_error_count
from ora01555_error_monitor
where error_time > sysdate – 1;
— 检查UNDO表空间使用率
select used_percent into v_undo_used_percent
from undo_tablespace_monitor
where rownum = 1;
if v_error_count > 0 or v_undo_used_percent > 80 then
— 发送告警
utl_smtp.open_connection(
host => ‘smtp.fgedu.net.cn’,
port => 25,
c => v_conn
);
utl_smtp.helo(v_conn, ‘localhost’);
utl_smtp.mail(v_conn, ‘oracle@fgedu.net.cn’);
utl_smtp.rcpt(v_conn, v_email);
utl_smtp.open_data(v_conn);
utl_smtp.write_data(v_conn, ‘Subject: ORA-01555 Error Alert’ || utl_tcp.crlf);
utl_smtp.write_data(v_conn, ‘To: ‘ || v_email || utl_tcp.crlf);
utl_smtp.write_data(v_conn, utl_tcp.crlf);
utl_smtp.write_data(v_conn, ‘ORA-01555 errors detected: ‘ || v_error_count || utl_tcp.crlf);
utl_smtp.write_data(v_conn, ‘UNDO tablespace usage: ‘ || v_undo_used_percent || ‘%’ || utl_tcp.crlf);
utl_smtp.close_data(v_conn);
utl_smtp.quit(v_conn);
end if;
end ora01555_error_alert;
/
Procedure created.
# 7. 创建定时任务
SQL> begin
dbms_scheduler.create_job(
job_name => ‘ORA01555_ERROR_ALERT_JOB’,
job_type => ‘STORED_PROCEDURE’,
job_action => ‘ORA01555_ERROR_ALERT’,
start_date => systimestamp,
repeat_interval => ‘FREQ=HOURLY;INTERVAL=1’,
enabled => true
);
end;
/
PL/SQL procedure successfully completed.
3.3 ORA-01555错误故障处理
3.3.1 ORA-01555错误处理
SQL> select * from employees where id = 123;
select * from employees where id = 123
*
ERROR at line 1:
ORA-01555: snapshot too old: rollback segment number 123 with name “_SYSSMU123_” too small
# 分析步骤
# 1. 查看告警日志
$ grep “ORA-01555” /oracle/app/oracle/diag/rdbms/fgedudb/FGEDUDB/trace/alert_FGEDUDB.log
2026-03-31T10:00:00.123456+08:00
ORA-01555: snapshot too old: rollback segment number 123 with name “_SYSSMU123_” too small
# 2. 查看UNDO表空间使用情况
SQL> select tablespace_name, bytes/1024/1024 as used_mb, maxbytes/1024/1024 as max_mb,
(bytes/maxbytes)*100 as used_percent
from dba_data_files
where tablespace_name like ‘UNDO%’;
TABLESPACE_NAME USED_MB MAX_MB USED_PERCENT
—————————— ———- ———- ————
UNDOTBS1 500 10240 4.8828125
# 3. 查看UNDO统计信息
SQL> select begin_time, end_time, undoblks, txncount, maxquerylen, ssolderrcnt, nospaceerrcnt
from v$undostat
where begin_time = (select max(begin_time) from v$undostat);
BEGIN_TIME END_TIME UNDOBLKS TXNCOUNT MAXQUERYLEN SSOLDERRCNT NOSPACEERRCNT
——————– ——————– ———- ———- ———– ———– ————-
31-MAR-26 10:00:00 31-MAR-26 11:00:00 1234 5678 3600 10 5
# 4. 分析错误原因
# 错误代码：ORA-01555
# 错误信息：snapshot too old
# 回滚段：_SYSSMU123_ too small
# 错误原因：UNDO表空间太小或查询时间过长
# 5. 解决方案：增加UNDO表空间大小
SQL> alter database datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs01.dbf’ resize 2048M;
Database altered.
# 6. 解决方案：增加UNDO保留时间
SQL> alter system set undo_retention = 3600 scope=both;
System altered.
# 7. 解决方案：优化查询
SQL> explain plan for select * from employees where id = 123;
Explained.
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
——————————————————————————–
Plan hash value: 123456789
——————————————————————————–
| Id | Operation | Name | Rows | Bytes | Cost |
——————————————————————————–
| 0 | SELECT STATEMENT | | 1 | 100 | 1 |
| 1 | TABLE ACCESS BY INDEX ROWID| EMPLOYEES | 1 | 100 | 1 |
|* 2 | INDEX UNIQUE SCAN | EMPLOYEES_PK | 1 | | 0 |
——————————————————————————–
# 8. 验证问题解决
SQL> select * from employees where id = 123;
ID NAME EMAIL PHONE CREDIT_CARD SSN BALANCE
———- ———- ———————- ————— —————— ———- ———-
123 风哥1号 zhangsan@fgedu.net.cn 13800138000 1234567890123456 123456789 10000
# 9. 预防措施
# – 定期监控UNDO表空间使用情况
# – 增加UNDO表空间大小
# – 增加UNDO保留时间
# – 优化长时间运行的查询
3.3.2 UNDO表空间优化
SQL> select tablespace_name, bytes/1024/1024 as used_mb, maxbytes/1024/1024 as max_mb,
(bytes/maxbytes)*100 as used_percent
from dba_data_files
where tablespace_name like ‘UNDO%’;
TABLESPACE_NAME USED_MB MAX_MB USED_PERCENT
—————————— ———- ———- ————
UNDOTBS1 2048 10240 20
# 2. 查看UNDO统计信息
SQL> select begin_time, end_time, undoblks, txncount, maxquerylen, ssolderrcnt, nospaceerrcnt
from v$undostat
order by begin_time desc
fetch first 10 rows only;
BEGIN_TIME END_TIME UNDOBLKS TXNCOUNT MAXQUERYLEN SSOLDERRCNT NOSPACEERRCNT
——————– ——————– ———- ———- ———– ———– ————-
31-MAR-26 10:00:00 31-MAR-26 11:00:00 1234 5678 3600 0 0
31-MAR-26 09:00:00 31-MAR-26 10:00:00 1234 5678 3600 0 0
31-MAR-26 08:00:00 31-MAR-26 09:00:00 1234 5678 3600 0 0
# 3. 计算UNDO表空间需求
SQL> select
round((undoblks * 8) / 1024, 2) as undo_mb,
round((maxquerylen / 60), 2) as max_query_min,
round((undoblks * 8) / 1024 * 1.5, 2) as recommended_undo_mb
from v$undostat
where begin_time = (select max(begin_time) from v$undostat);
UNDO_MB MAX_QUERY_MIN RECOMMENDED_UNDO_MB
———- ————- ——————–
9.77 60 14.65
# 4. 优化UNDO表空间大小
SQL> alter database datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs01.dbf’ resize 4096M;
Database altered.
# 5. 优化UNDO保留时间
SQL> alter system set undo_retention = 7200 scope=both;
System altered.
# 6. 验证配置
SQL> show parameter undo
NAME TYPE VALUE
———————————— ———– ——————————
undo_management string AUTO
undo_retention integer 7200
undo_tablespace string UNDOTBS1
# 7. 监控UNDO表空间使用情况
SQL> select tablespace_name, bytes/1024/1024 as used_mb, maxbytes/1024/1024 as max_mb,
(bytes/maxbytes)*100 as used_percent
from dba_data_files
where tablespace_name like ‘UNDO%’;
TABLESPACE_NAME USED_MB MAX_MB USED_PERCENT
—————————— ———- ———- ————
UNDOTBS1 4096 10240 40
Part04-生产案例与实战讲解
4.1 ORA-01555错误分析案例
在生产环境中分析ORA-01555错误的完整案例：
4.1.1 场景描述
某企业生产数据库出现ORA-01555快照过旧错误，需要分析错误原因并解决问题。
4.1.2 分析步骤
SQL> select * from v$session_wait where event like ‘%undo%’;
SID SERIAL# EVENT WAIT_TIME SECONDS_IN_WAIT STATE P1TEXT P1 P2TEXT P2 P3TEXT P3
—— ———- ————————- ———- ————— ——– ———- — ———- — ———- —
123 45678 SQL*Net message from client 0 0 WAITING driver id 1413697536 #bytes 1
# 2. 查看告警日志
$ grep “ORA-01555” /oracle/app/oracle/diag/rdbms/fgedudb/FGEDUDB/trace/alert_FGEDUDB.log | tail -20
2026-03-31T10:00:00.123456+08:00
ORA-01555: snapshot too old: rollback segment number 123 with name “_SYSSMU123_” too small
2026-03-31T10:00:01.234567+08:00
ORA-01555: snapshot too old: rollback segment number 123 with name “_SYSSMU123_” too small
# 3. 查看UNDO表空间使用情况
SQL> select tablespace_name, bytes/1024/1024 as used_mb, maxbytes/1024/1024 as max_mb,
(bytes/maxbytes)*100 as used_percent
from dba_data_files
where tablespace_name like ‘UNDO%’;
TABLESPACE_NAME USED_MB MAX_MB USED_PERCENT
—————————— ———- ———- ————
UNDOTBS1 500 10240 4.8828125
# 4. 查看UNDO统计信息
SQL> select begin_time, end_time, undoblks, txncount, maxquerylen, ssolderrcnt, nospaceerrcnt
from v$undostat
where begin_time = (select max(begin_time) from v$undostat);
BEGIN_TIME END_TIME UNDOBLKS TXNCOUNT MAXQUERYLEN SSOLDERRCNT NOSPACEERRCNT
——————– ——————– ———- ———- ———– ———– ————-
31-MAR-26 10:00:00 31-MAR-26 11:00:00 1234 5678 3600 10 5
# 5. 分析错误原因
# 错误代码：ORA-01555
# 错误信息：snapshot too old
# 回滚段：_SYSSMU123_ too small
# 错误原因：UNDO表空间太小或查询时间过长
# 6. 解决方案：增加UNDO表空间大小
SQL> alter database datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs01.dbf’ resize 2048M;
Database altered.
# 7. 解决方案：增加UNDO保留时间
SQL> alter system set undo_retention = 3600 scope=both;
System altered.
# 8. 验证问题解决
SQL> select * from employees where id = 123;
ID NAME EMAIL PHONE CREDIT_CARD SSN BALANCE
———- ———- ———————- ————— —————— ———- ———-
123 风哥1号 zhangsan@fgedu.net.cn 13800138000 1234567890123456 123456789 10000
4.2 ORA-01555错误故障处理
在ORA-01555错误故障处理过程中的方法和技巧：
4.2.1 故障处理流程
# 1. 错误识别
# – 监控告警日志
# – 检查错误信息
# – 确认错误参数
# 2. 错误分析
# – 查看UNDO表空间使用情况
# – 分析UNDO统计信息
# – 分析查询执行时间
# 3. 错误处理
# – 增加UNDO表空间大小
# – 增加UNDO保留时间
# – 优化查询
# 4. 错误预防
# – 定期监控UNDO表空间
# – 定期优化查询
# – 制定预防措施
# 示例：ORA-01555错误处理
# 1. 错误识别
SQL> select * from employees where id = 123;
select * from employees where id = 123
*
ERROR at line 1:
ORA-01555: snapshot too old: rollback segment number 123 with name “_SYSSMU123_” too small
# 2. 错误分析
SQL> select tablespace_name, bytes/1024/1024 as used_mb, maxbytes/1024/1024 as max_mb,
(bytes/maxbytes)*100 as used_percent
from dba_data_files
where tablespace_name like ‘UNDO%’;
TABLESPACE_NAME USED_MB MAX_MB USED_PERCENT
—————————— ———- ———- ————
UNDOTBS1 500 10240 4.8828125
# 3. 错误处理
SQL> alter database datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs01.dbf’ resize 2048M;
Database altered.
SQL> alter system set undo_retention = 3600 scope=both;
System altered.
# 4. 验证处理结果
SQL> select * from employees where id = 123;
ID NAME EMAIL PHONE CREDIT_CARD SSN BALANCE
———- ———- ———————- ————— —————— ———- ———-
123 风哥1号 zhangsan@fgedu.net.cn 13800138000 1234567890123456 123456789 10000
# 5. 错误预防
# – 定期监控UNDO表空间使用情况
# – 增加UNDO表空间大小
# – 增加UNDO保留时间
# – 优化长时间运行的查询
4.3 ORA-01555错误优化
优化ORA-01555错误处理配置的最佳实践：
4.3.1 优化UNDO表空间
SQL> create or replace procedure optimize_undo_tablespace as
v_undo_used_percent number;
v_max_query_len number;
v_recommended_undo_mb number;
begin
— 获取UNDO表空间使用率
select used_percent into v_undo_used_percent
from undo_tablespace_monitor
where rownum = 1;
— 获取最大查询时间
select maxquerylen into v_max_query_len
from v$undostat
where begin_time = (select max(begin_time) from v$undostat);
— 计算推荐的UNDO表空间大小
select round((undoblks * 8) / 1024 * 1.5, 2) into v_recommended_undo_mb
from v$undostat
where begin_time = (select max(begin_time) from v$undostat);
— 如果UNDO表空间使用率超过80%，建议增加大小
if v_undo_used_percent > 80 then
dbms_output.put_line(‘UNDO tablespace usage is ‘ || v_undo_used_percent || ‘%’);
dbms_output.put_line(‘Recommended UNDO tablespace size: ‘ || v_recommended_undo_mb || ‘ MB’);
end if;
— 如果最大查询时间超过UNDO保留时间，建议增加保留时间
if v_max_query_len > 3600 then
dbms_output.put_line(‘Max query length is ‘ || v_max_query_len || ‘ seconds’);
dbms_output.put_line(‘Recommended UNDO retention: ‘ || v_max_query_len + 1800 || ‘ seconds’);
end if;
end optimize_undo_tablespace;
/
Procedure created.
# 2. 执行优化存储过程
SQL> set serveroutput on
SQL> exec optimize_undo_tablespace;
UNDO tablespace usage is 85%
Recommended UNDO tablespace size: 2048 MB
Max query length is 3600 seconds
Recommended UNDO retention: 5400 seconds
PL/SQL procedure successfully completed.
# 3. 应用优化建议
SQL> alter database datafile ‘/oracle/app/oracle/oradata/FGEDUDB/undotbs01.dbf’ resize 2048M;
Database altered.
SQL> alter system set undo_retention = 5400 scope=both;
System altered.
# 4. 创建定时任务
SQL> begin
dbms_scheduler.create_job(
job_name => ‘OPTIMIZE_UNDO_TABLESPACE_JOB’,
job_type => ‘STORED_PROCEDURE’,
job_action => ‘OPTIMIZE_UNDO_TABLESPACE’,
start_date => systimestamp,
repeat_interval => ‘FREQ=DAILY;INTERVAL=1’,
enabled => true
);
end;
/
PL/SQL procedure successfully completed.
Part05-风哥经验总结与分享
5.1 ORA-01555错误总结
Oracle ORA-01555错误是快照过旧错误，具有以下特点：
- 快照过旧：数据块被覆盖
- 回滚段：回滚段空间不足
- 一致性：无法读取一致性数据
- 长时间查询：长时间运行的查询
- 需要调整：需要调整回滚段大小
5.2 ORA-01555错误检查清单
Oracle ORA-01555错误检查清单：
- 错误识别：识别错误信息和参数
- 错误分析：分析UNDO表空间使用情况
- 错误处理：处理错误问题
- 错误验证：验证处理结果
- 错误预防：制定预防措施
- 错误记录：记录处理过程
5.3 ORA-01555错误工具推荐
Oracle ORA-01555错误工具推荐：
- SQL*Plus：命令行工具
- SQL Developer：图形化工具
- Enterprise Manager：企业级管理工具
- AWR报告：自动工作负载仓库报告
- ASH报告：活动会话历史报告
- Statspack：性能统计包
- ADDM：自动数据库诊断监视器
本文由风哥教程整理发布,仅用于学习测试使用,转载注明出处:http://www.fgedu.net.cn/10327.html
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