BLOB 在线备份的速度
在 Oracle 8 中，使用数据库中的 BLOB 进行在线备份非常慢。 我所说的“慢”是指备份一个包含 100MB BLOB 数据的数据库需要一个多小时。 Oracle 承认速度很慢，但不会解决问题（需要支付支持费用）。有谁知道 Oracle 是否在后续版本中解决了这个问题？ 另外，在 SQL Server 和 MySQL 中使用 BLOB 进行在线备份的速度有多快？
In Oracle 8 doing an online backup with BLOBs in the database is extremely slow. By slow, I mean over an hour to backup a database with 100MB of BLOB data. Oracle acknowledged it was slow, but wouldn't fix the problem (so much for paying for support.) Does anyone know if Oracle has fixed this problem with subsequent releases? Also, how fast do online backups work with BLOBs work in SQL Server and MySQL?
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我过去遇到过这个问题，我们发现的唯一合适的解决方法是确保 LOB 位于它们自己的表空间中，并对它们使用不同的备份策略，或者切换到使用 BFILE 类型。 您能否使用 BFILE 将取决于您如何使用 LOB。
BFILE 的一些使用信息：
http: //download-uk.oracle.com/docs/cd/B10501_01/java.920/a96654/oralob.htm#1059942
请注意，BFILE 位于 Oracle 外部的文件系统上，因此您需要支持它们在正常 Oracle 备份之外的进程中进行备份。 在一个项目中，我们刚刚安排了一次 rsync 到异地备份。 另外需要注意的是，您无法通过 JDBC 创建/更新 BFILE，但可以读取它们。
I've had this issue in the past, and the only decent workarounds we found were to make sure that the LOBs were in their own tablespace, and use a different backup strategy with them, or to switch to using the BFILE type. Whether or not you can get by with BFILE will depend on how you're using the LOBs.
Some usage info on BFILE:
http://download-uk.oracle.com/docs/cd/B10501_01/java.920/a96654/oralob.htm#1059942
Note that BFILEs live on the filesystem outside of Oracle, so you'd need to back them up in a process outside of your normal Oracle backup. On one project we just had a scheduled rsync to offsite backup. Also important to note is that you cannot create/update BFILEs via JDBC, but you can read them.
要回答有关 SQL Server 中 BLOB 在线备份速度的问题，它与备份 SQL 2000/2005/2008 的常规数据的速度相同 - 它通常受到存储速度的限制。 我的 BLOB 数据库备份速度通常超过 100mb/秒。
不过，在使用备份压缩工具时要小心 - 如果 BLOB 是高度随机的二进制类型数据，那么您将浪费 CPU 周期来尝试压缩数据，并且压缩会使备份速度变慢而不是更快。
To answer your question about the speed of online backups of BLOBs in SQL Server, it's the same speed as backing up regular data for SQL 2000/2005/2008 - it's typically limited by the speed of your storage. I usually get over 100mb/sec on my database backups with BLOBs.
Be wary of using backup compression tools with those, though - if the BLOB is binary-style data that's heavily random, then you'll waste CPU cycles trying to compress the data, and compression can make the backup slower instead of faster.
我使用 Redgate for SQL Server 的 SQL 备份 —— 即使对于 BLOB 数据，它也快得离谱。
我保留了进行 EDI 处理的每个文件的副本，因此虽然它们并不大，但它们数量众多且为 BLOB。 仅这些文本文件我就已经超过 100Meg。
值得注意的是，Redgate 的 SQL 备份只是标准 SQL 备份的前端...它基本上为您提供了额外的管理功能，但仍然利用 SQL Server 备份引擎。
I use SQL Backup from Redgate for SQL Server -- it is ridiculously fast, even with my BLOB data.
I keep a copy of every file that I do EDI with, so while they aren't huge, they are numerous and BLOBs. I'm well over 100Megs of just these text files.
It's important to note that Redgate's SQL Backup is just a front-end to the standard SQL Backup...it gives you additional management features, basically, but still utilizes the SQL Server backup engine.
根据 BLOB 的大小，确保将它们适当地存储在行内/行外。
请参阅http://www.dba-oracle.com/t_table_blob_lob_storage.htm
Depending on the size of the BLOBs, make sure you're storing them in-line / out of line appropriately.
See http://www.dba-oracle.com/t_table_blob_lob_storage.htm
您可以将正在创建的导出文件和 Oracle 表空间放在不同的磁盘上吗？ 您的 I/O 吞吐量可能是限制因素......？
Can you put the export file you're creating and the Oracle tablespaces on different disks? You I/O throughput may be the constraining factor...?
8i 上的 exp 很慢，但没有你描述的那么慢。 我在 10g 的几分钟内备份了 GB 的 blob..（到磁盘 - 使用 expdp）
exp on 8i was slow, but not as much as you describe. I have backed-up gigabytes of blobs in minutes in 10g..(to disk - using expdp)