WINDOWS下的程序员出身，偶尔也写一些linux平台下小程序， 后转行数据库行业，专注于ORACLE和DB2的运维和优化。 同时也是ios移动开发者。欢迎志同道合的朋友一起研究技术。 数据库技术交流群：58308065，23618606
全部博文（599）
发布时间：2012-12-29 21:09:07
By default RMAN has three types of compression : 1. Null Compression2. Unused Block Compression3. Binary CompressionTill Oracle Version 10.1 only 'Null' compression in done by default but from Oracle Version 10.2 'Null' and 'Unused Bloc'k Compression is done. T......【阅读全文】
发布时间：2012-12-28 10:04:53
Beginning with Oracle10G, when statistics are gathered for a table, the old statistics are retained so should there be any problem with performance of queries dependent on those statistics, the old ones can be restored.How long does Oracle retain the statistics for ? The default peri......【阅读全文】
发布时间：2012-12-27 16:02:02
如果我们的SQL采用了ROWNUM=1的查询方法，而且系统的CURSOR_SHARING设置了SIMILAR，那么我们很有可能遇到Bug 4513695。ORACLE并不承认这是个BUG，以下是ORACLE给出的解释： This is not really a bug as CURSOR_SHARING=SIMILAR does not give the optimizer all of the same information that EXACT would give it. However, it looks ......【阅读全文】
发布时间：2012-12-27 10:40:02
You cannot export any schema that contains dictionary metadata. This is a restriction of export process.Schemas that exclusively contain dictionary objects like SYS, CTXSYS, MDSYS and ORDSYS are never exported nor imported. This is because these schemas are created when you install the related......【阅读全文】
发布时间：2012-12-26 10:55:44
今天有同事问到如何移动一个LOB索引到其他表空间。LOB索引的特殊性使得REBUILD是不可行的。要移动LOB索引到其他表空间，需要将相应的LOB对象移动到其他表空间。SQL> CREATE TABLE TEST(ID INT,NAME VARCHAR2(20),CONTENTS CLOB);表已创建。SQL> ALTER INDEX "SYS_IL0000052966C00003$$" REBUILD;ALTER INDEX "SYS_IL0000052966C00003$$" REBUILD*第 1 行出现错误:ORA-02327: 无法以数据类型 LOB 的表达式创建索引SQ......【阅读全文】
前期吸引人啊