select row number

I. Introduction of row migration and row link in actual work we often encounter some problems with low Oracle database performance. Of course, there are many reasons that cause low Oracle database performance, we can use some correct design and

Row chain: When a row is too large to fit into any block, row chaining occurs. in this case, the Oracle devide the row into smaller chunks. each Chunk is stored in a block along with the necessary poiters to retrive and assemble the entire row.

Scenario: If varchar and VarChar2 are modified more often, and the modified data length is different each time, this can cause a "row migration" phenomenonConcept:Row chaining and row migration (row migration)When a row of data is too long to be

Reprint Please specify: theviper http://www.cnblogs.com/TheViperPartially translated from How to select the First/least/max row per group in SQLSome common SQL problems have similar workarounds, such as finding the most recent logs for each program,

This section focuses on ExtJS4.2 grid multi-select line knowledge, example Image:650) this.width=650; "alt=" ExtJS4.2 grid knowledge Point five: Multiple select rows (you can click on the row to select the record and only click on the Multi-box to

In the actual work we often encounter some Oracle database performance is low, of course, the reasons for the low performance of Oracle database is various, we can through some correct design and diagnosis to try to avoid some Oracle database

Row migrations and row links lead to degraded Oracle performance, this article describes what row migration and row links are, what they do, how to judge them, and provides solutions to them.What is row migration and row link row migrationOracle's

-- Row-by-row calculation, row-by-row deferred, and row-by-row update Declare @ TB table (Employee ID int, name nvarchar (10), number int, base int, start int, end INT) Insert @ Tb (employee ID, name, quantity) select 1, n 'zhang san', 5 Insert @

Because of the row link can only increase db_block_size to clear, and db_block_size after the creation of the database can not be changed, so there is no more than the purge of the row link, mainly for the row migration to talk about in the actual

What is a row migration row link? # The following description is from Oracle11gR2Document1. The row link Therowistoolargetofitintoonedatablockwhenitisfirstinserted. Inrowchaining, OracleDatabasestor What is a row migration row link? # The following