使用cache或许会跳号, 比如数据库突然不正常down掉(shutdown abort),cache中的sequence就会丢失. 所以可以在create sequence的时候用nocache防止这种情况。 2、Alter Sequence 你或者是该sequence的owner,或者有ALTER ANY SEQUENCE 权限才能改动sequence. 可以alter除start至以外的所有sequence参数.如果想要改变start值,必须...
Therefore, the sequence generator reduces serialization where the statements of two transactions must generate sequential numbers at the same time. By avoiding the serialization that results when multiple users wait for each other to generate and use a sequence number, the sequence generator improves tr...
ORDERguarantees that sequence numbers are generatedinorderofrequest.You may want to usethisoptionifyou are using the sequence numbersastimestamps.Guaranteeing order is usually not importantforsequences used to generate primary keys.NOORDERdoes not guarantee sequence numbers are generatedinorderofrequest.I...
xttprepareNaNd- the command tsbkupmap.txt- containing the tablespace names, datafile numbers and the incremental backup pieces incrbackups.txt- containing the actual location of the incremental backup pieces rmanincrNaNd- containing the RMAN scripts used to create the incremental backups. xttdetnewfr...
CACHENOCACHE NOCACHECACHENOCACHEORDERto guarantee that sequence numbers are generated in order of request. This clause is useful if you are using the sequence numbers as timestamps. Guaranteeing order is usually not important for sequences used to generate primary keys. ...
Oracle invented sequences to make it possible to supply on demand a (virtually) limitless sequence of numbers that were guaranteed to be unique. The easiest way to do this is simply to keep a globally visible counter and increment it every time a session says: “give me a number” (or,...
PLSQL APIs Components in this advanced pack are being delivered for some of the key public APIs that are available in 12.1.3 release. The Components are defined at the level of the API - Method - Overload sequence. The API signature for the method is captured in the definition of the ma...
Table 10-23 Sequences Defined for Data Mining Table NameSequence Name DWR_CUST_SGMNT CUST_SGMNT_SEQ Data Mining Package Customer Life Time Value Computation In addition to the prebuilt data mining models, Oracle Communications Data Model core data mining package also includes a procedure for prep...
Incremental values, such as ascending sequence numbers or increasingly later date values, are always added to the right side of the index, which is the home of higher and higher values. In addition, any deletions from the index have a tendency to be skewed toward the left side as older ...
You can retrieve the return value for an Oracle function only by using a RETURN parameter (shown in the previous section) and not by using the one of the ExecuteScalar methods. Sequences Oracle uses a sequence to generate unique numbers rather than the data type uniqueidentifier used by SQL ...