ORA-00600 [qkssao2s1] internal error issue

ORA-00600: internal error code, arguments: [ORA-00600: internal error code, arguments: [qkssao2s1], [], [], [], [], [], [], []

SQL hint mean force? More about parallel(二)(不并行的场景)

sql中如果使用了parallel hint 或是force parallel query 想并行查询的特性,如果那样做了就一定能保证 query optimizer选择并行的执行计划么?知道那样做实际上产生什么样的影响么?

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More about ITL in oracle

ITL(Interested Transaction List ),The Oracle database engine locks the data modified by a transaction at the row level. To implement this feature every data block contains a list of all transactions that are modifying it. This list is commonly called interested transaction list (ITL).

Oracle GoldenGate Trail File

Trail files are generated by both the original extract and the Data Pump (extract) process. Trail files are read by the Data Pump (extract) and Replicat (replicat) processes

Schema level flashback(闪回用户或方案)

Technically there is no schema level flashback feature […]

Script: Who’s using a database link?(找出谁在使用dblink)

Every once in awhile it is useful to find out which ses […]

More about index

创建索引可以方便的给DB带来查询上的性能提升,但是DML时index的维护代价也是昂贵的。合理的创建索引,删除不必要的索引。

Tuning PGA Memory

You can get the correct size of PGA using V$PGA_TARGET_ADVICE, dynamic performance view.

HAVING expression default Selectivity

In some cases the query optimizer might can not accurately estimate cardinality (e.g. group by having or like with bind variables cause etc..),therefore the Cardinality estimates are based on default seletivity of build-in oracle coredefault seletivity(5%).