create index logging, nologging performance test

create index logging, nologging performance test.

For Speed up when creating an index for a large table. we can use nologging clause .

test result:

1, nologging is effective in archivelog database mode. Although, in noarchivelog database mode, by default ,create index will not produce much log , by other words, it's the same speed in noarchivelog mode whether nologging clause is supplied.

2, use nologging clause , performance would improve 40% more or less accord actual environment.

3, parallel is only effective if you have multiple spindles.

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some notes:

insert /*+ append */ wil degrade (at least 2 times) when index exists, so the better way maybe is drop index first, then load data, the create index at last.

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