tailieunhanh - SQL Anywhere Studio 9- P9

Tham khảo tài liệu 'sql anywhere studio 9- p9', công nghệ thông tin, cơ sở dữ liệu phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 436 Chapter 10 Tuning Here is an example of an ALTER DBSPACE statement that adds 800 megabytes to a main database file ALTER DBSPACE SYSTEM ADD 800 MB Formore information about ALTER DBSPACE see Section File Fragmentation earlier in this chapter. Step 8 Defragment the hard drive. Disk fragmentation hurts performance and this is an excellent opportunity to make it go away. This step is performed after the database is increased in size Step 7 because some disk defragmentation tools only work well on existing files. Step 9 Examine the file for logical problems and edit the file to fix them if necessary. You can perform this step any time after Step 2 and it is completely optional. Sometimes however databases are subject to schema drift over time where errors and inconsistencies creep into the database design. At this point in the process the entire schema is visible in the text file and you have an opportunity to check it and fix it. Some problems can be easily repaired for example removing an unnecessary CHECK constraint dropping a user id that is no longer used or fixing an option setting. Other problems are more difficult for example you can add a column to a table but deleting a column from a CREATE TABLE statement may also require a change to the corresponding LOAD TABLE statement see Section LOAD TABLE for more information about how to skip an input column with the special keyword filler . Tip At this point double-check the setting of database option OPTIMIZA-TION_GOAL. Make sure the file contains the statement SET OPTION PUBLIC . OPTIMIZATION_GOAL all-rows if that is what you want the setting to be and you probably do. In particular check the value after unloading and reloading to upgrade from an earlier version the reload process may set this option to the value you probably do not want first-row . Step 10 Reload the database by running via ISQL. This may be the most time-consuming step of all with Steps 2