database row

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

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 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

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

First, IntroductionThere are two alternatives to big data storage: Row and column storage. The industry has a lot to do with the two storage scenarios, focusing on who can handle massive amounts of data more efficiently, with security, reliability,

Through the previous introduction we know that the main line link is due to the db_block_size of the database is not large enough for some large fields can not be stored in a block, resulting in a row link. For row links We have nothing to avoid

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

1, row-type databaseDefinition: The storage format stores the data of a row of fields in a ' row ' way, and a row of rows is continuously stored.Figure 1It is both intuitive and efficient to write information about a piece of data into a database,

How to lock a row table database 1 how to lock a row of a table SET transaction isolation level read uncommitted Select * from Table rowlock where id = 1 2. Lock a table in the database Select * from table with (holdlock) Lock