Index rebuild

alter index index_name tablespace tbs_name rebuild online parallel 2;

The parallel parameter works only in Enterprise edition of oracle.

Because parallelism doesnt comes free with Standard Edition. Same way the compression techniques used in oralce, for example compressed backup, compressed table(LOB), compressed expdp, compressed archive log files for standby.

Index rebuild with online option requires disk space equal to the size of the index in-order to make the index usable for the current running sessions which ever required.

 
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