|Index Rebuild||Index Reorganize|
|It is offline operation||It is online operation|
|Option is available in all SQL Server 2005 edition||Option is available in SQL Server 2005 Enterprise and Developer edition only|
|Index rebuilds works by re-creating the index internally again and when that has been achieved, it drops the existing index.||Index reorganize is the process of physically re-organizing the leaf nodes of the index|
|Index rebuild need more log space so it is advisable to change the database recovery model Simple or Bulk-logged||Reorganize swaps one page with another and thus does not require free space for this operation like rebuild does. Infect, reorganize can free up some pages as it does the reorganize in two phases – compaction and defrag.
A reorganize can remove almost all of the logical fragmentation but it cannot necessarily fix extent fragmentation in which the previous and the next extents are physically contiguous.
|During the index rebuild process, It will also re-compute index statistics||Reorganize on the other hand does not update the statistics|
|Can be done on any data type column because it is offline operation.||Another point to note is that an index (clustered or non-clustered) cannot be built online if it contains LOB data (text, ntext, varchar(max), nvarchar(max), varbinary(max), image and xml data type columns).|
|If you want to rebuild an index with multiple partitions in an online environment, you need to rebuild the entire index which means rebuilding all the partitions.||Regarding partitions of an index, if an index has multiple partitions, then you cannot rebuild a single partition online. You can reorganize a single index partition online|
|Index should be rebuild when index fragmentation is great than 40%.||Index should be reorganized when index fragmentation is between 10% to 40%|
|ONLINE option will not keep index available during the rebuilding.||ONLINE option will keep index available during the rebuilding.|