After working on a problem where the transaction logs for a large database were filling to sizes larger then the actual database every night it turned out to be a server maintenance plan that rebuilt and reorganized indexes every night. While working on designing a custom plan that would only rebuild or reorganize when actually necessary I found many references out on the internet. None of the scripts I found out there really accomplished what I was after.
Starting with finding the indexes that need maintenance done on them I eventually came up with this SQL:
select
sch.name [schema_name]
,obj.name [table_name]
,idx.name [index_name]
,idx.type_desc [index_type]
,part.used_page_count*8 [used_kb] --each page is 8k
,part.row_count
,CONVERT(DECIMAL(9,2),frag.avg_fragmentation_in_percent) [fragmentation]
from sys.dm_db_partition_stats part
join sys.objects obj on part.object_id = obj.object_id
join sys.schemas sch on obj.schema_id = sch.schema_id
left join sys.indexes idx on part.object_id = idx.object_id and part.index_id = idx.index_id
left join sys.dm_db_index_physical_stats(db_id(),null,null,null,null) frag on part.object_id = frag.object_id
and part.index_id = frag.index_id
where
obj.is_ms_shipped = 0
and frag.page_count > 100
order by [schema_name],[table_name],[index_name];
This gave me a nice view to see how big the tables were, and where the fragmentation problems were. We decided that if it’s less800KB (based on frag.page_count) we didn’t care about the fragmentation.
Armed with this info it was a matter of basically executing the rebuild or reorganize depending on your preference. I decided to use a in memory table and just did a insert-select into it. My temp table looked like:
declare @IndexStatus table(
schema_name varchar(250)
,table_name varchar(250)
,index_name varchar(250)
,index_type varchar(250)
,used_kb int
,row_count int
,fragmentation decimal(9,2));
From there I just took the results into a cursor and executed dynamic sql. My logic was <10% fragmentation I didn’t care, greater then 30 gets a rebuild, 10-30 gets a reorganize
declare maintCursor cursor for
select 'alter index ['+[index_name]+'] on ['+[schema_name]+'].['+[table_name]+']', fragmentation
from @IndexStatus
where fragmentation > 10;
declare @stmt varchar(max);
declare @frag float;
open maintCursor
fetch next from maintCursor into @stmt, @frag
while @@fetch_status = 0
begin
if @frag > 30
set @stmt = @stmt+' rebuild'; --if this is enterprise you can add 'with (online=on)'
else
set @stmt = @stmt+' reorganize';
print (@stmt)
exec (@stmt)
fetch next from maintCursor into @stmt, @frag
end
close maintCursor
deallocate maintCursor
