fsugeiger: SQL Server Index and Statistics Maintenance

Just attended Orlando.Net Code Camp this past weekend and set in on a session from Rob Biddle a Data Architect where he had a recommended a Ola Hallengren index and stats maintenance process. Just wrapping up testing on the dev box now and slowly folding them into my production maintenance routine. Something you should check out.

Resource Link:
http://ola.hallengren.com/sql-server-index-and-statistics-maintenance.html

IndexOptimize is the SQL Server Maintenance Solution’s stored procedure for rebuilding and reorganizing indexes and updating statistics. IndexOptimize is supported on SQL Server 2005, SQL Server 2008, SQL Server 2008 R2, and SQL Server 2012.

Download

Download MaintenanceSolution.sql. This script creates all the objects and jobs that you need. You can also download the objects as separate scripts.

License

The SQL Server Maintenance Solution is free.

Support

Request professional support or custom modifications.

Parameters

Databases

Select databases. The keywords SYSTEM_DATABASES, USER_DATABASES, and ALL_DATABASES are supported. The hyphen character (-) is used to exclude databases, and the percent character (%) is used for wildcard selection. All of these operations can be combined by using the comma (,).

Value	Description
SYSTEM_DATABASES	All system databases (master, msdb, and model)
USER_DATABASES	All user databases
ALL_DATABASES	All databases
Db1	The database Db1
Db1, Db2	The databases Db1 and Db2
USER_DATABASES, -Db1	All user databases, except Db1
%Db%	All databases that have “Db” in the name
%Db%, -Db1	All databases that have “Db” in the name, except Db1
ALL_DATABASES, -%Db%	All databases that do not have “Db” in the name

FragmentationLow

Specify index maintenance operations to be performed on a low-fragmented index.

Value	Description
INDEX_REBUILD_ONLINE	Rebuild index online.
INDEX_REBUILD_OFFLINE	Rebuild index offline.
INDEX_REORGANIZE	Reorganize index.
INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE	Rebuild index online. Rebuild index offline if online rebuilding is not supported on an index.
INDEX_REBUILD_ONLINE,INDEX_REORGANIZE	Rebuild index online. Reorganize index if online rebuilding is not supported on an index.
INDEX_REORGANIZE,INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE	Reorganize index. Rebuild index online if reorganizing is not supported on an index. Rebuild index offline if reorganizing and online rebuilding are not supported on an index.
NULL	Do not perform index maintenance. This is the default for a low-fragmented index.

An online index rebuild or an index reorganization is not always possible. Because of this, you can specify multiple index-maintenance operations for each fragmentation group. These operations are prioritized from left to right: If the first operation is supported for the index, then that operation is used; if the first operation is not supported, then the second operation is used (if supported), and so on. If none of the specified operations are supported for an index, then that index is not maintained.
IndexOptimize uses the SQL Server ALTER INDEX command: REBUILD WITH (ONLINE = ON) to rebuild indexes online, REBUILD WITH (ONLINE = OFF) to rebuild indexes offline, and REORGANIZE to reorganize indexes.

FragmentationMedium

Specify index maintenance operations to be performed on a medium-fragmented index.

Value	Description
INDEX_REBUILD_ONLINE	Rebuild index online.
INDEX_REBUILD_OFFLINE	Rebuild index offline.
INDEX_REORGANIZE	Reorganize index.
INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE	Rebuild index online. Rebuild index offline if online rebuilding is not supported on an index.
INDEX_REBUILD_ONLINE,INDEX_REORGANIZE	Rebuild index online. Reorganize index if online rebuilding is not supported on an index.
INDEX_REORGANIZE,INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE	Reorganize index. Rebuild index online if reorganizing is not supported on an index. Rebuild index offline if reorganizing and online rebuilding are not supported on an index. This is the default for a medium-fragmented index.
NULL	Do not perform index maintenance.

FragmentationHigh

Specify index maintenance operations to be performed on a high-fragmented index.

Value	Description
INDEX_REBUILD_ONLINE	Rebuild index online.
INDEX_REBUILD_OFFLINE	Rebuild index offline.
INDEX_REORGANIZE	Reorganize index.
INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE	Rebuild index online. Rebuild index offline if online rebuilding is not supported on an index. This is the default for a high-fragmented index.
INDEX_REBUILD_ONLINE,INDEX_REORGANIZE	Rebuild index online. Reorganize index if online rebuilding is not supported on an index.
INDEX_REORGANIZE,INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE	Reorganize index. Rebuild index online if reorganizing is not supported on an index. Rebuild index offline if reorganizing and online rebuilding are not supported on an index.
NULL	Do not perform index maintenance.

FragmentationLevel1

Set the lower limit, as a percentage, for medium fragmentation. The default is 5 percent. This is based on Microsoft’s recommendation in Books Online.
IndexOptimize checks avg_fragmentation_in_percent in sys.dm_db_index_physical_stats to determine the fragmentation.

FragmentationLevel2

Set the lower limit, as a percentage, for high fragmentation. The default is 30 percent. This is based on Microsoft’s recommendation in Books Online.
IndexOptimize checks avg_fragmentation_in_percent in sys.dm_db_index_physical_stats to determine the fragmentation.

PageCountLevel

Set a size, in pages; indexes with fewer pages are skipped for index maintenance. The default is 1000 pages. This is based on Microsoft’s recommendation in this white paper.
IndexOptimize checks page_count in sys.dm_db_index_physical_stats to determine the size of the index.

SortInTempdb

Use tempdb for sort operations when rebuilding indexes.

Value	Description
Y	Use tempdb for sort operations when rebuilding indexes.
N	Do not use tempdb for sort operations when rebuilding indexes. This is the default.

The SortInTempdb option in IndexOptimize uses the SORT_IN_TEMPDB option in the SQL Server ALTER INDEX command.

MaxDOP

Specify the number of CPUs to use when rebuilding indexes. If this number is not specified, the global maximum degree of parallelism is used.
The MaxDOP option in IndexOptimize uses the MAXDOP option in the SQL Server ALTER INDEX command.

FillFactor

Indicate, as a percentage, how full the pages should be made when rebuilding indexes. If a percentage is not specified, the fill factor in sys.indexes is used.
The FillFactor option in IndexOptimize uses the FILLFACTOR option in the SQL Server ALTER INDEX command.

PadIndex

Apply the percentage of free space that the FillFactor parameter specifies to the intermediate-level pages of the index.

Value	Description
Y	Apply the percentage of free space that the FillFactor parameter specifies to the intermediate-level pages of the index.
N	The intermediate-level pages of the index are filled to near capacity. This is the default.

The PadIndex option in IndexOptimize uses the PADINDEX option in the SQL Server ALTER INDEX command.

LOBCompaction

Compact pages that contain large object (LOB) columns, when reorganizing indexes.

Value	Description
Y	Compact pages that contain LOB columns, when reorganizing indexes. This is the default.
N	Do not compact pages that contain LOB columns, when reorganizing indexes.

The LOBCompaction option in IndexOptimize uses the LOB_COMPACTION option in the SQL Server ALTER INDEX command.

UpdateStatistics

Update statistics.

Value	Description
ALL	Update index and column statistics.
INDEX	Update index statistics.
COLUMNS	Update column statistics.
NULL	Do not perform statistics maintenance. This is the default.

IndexOptimize uses the SQL Server UPDATE STATISTICS command to update statistics.

StatisticsSample

Indicate, as a percentage, how much of a table is gathered when updating statistics. A value of 100 is equivalent to a full scan. If no value is specified, then SQL Server automatically computes the required sample.
The StatisticsSample option in IndexOptimize uses the SAMPLE and FULLSCAN options in the SQL Server UPDATE STATISTICS command.

StatisticsResample

Update statistics with the most recent sample.

Value	Description
Y	Update statistics with the most recent sample.
N	Let SQL Server automatically compute the required sample. This is the default.

The StatisticsResample option in IndexOptimize uses the RESAMPLE option in the SQL Server UPDATE STATISTICS command.
You cannot combine the options StatisticsSample and StatisticsResample.

OnlyModifiedStatistics

Update statistics only if any rows have been modified since the most recent statistics update.

Value	Description
Y	Update statistics only if any rows have been modified since the most recent statistics update.
N	Update statistics regardless of whether any rows have been modified.

IndexOptimize checks rowmodctr in sys.sysindexes to determine whether any rows have been modified since the most recent statistics update.

PartitionLevel

Maintain partitioned indexes on the partition level. If this parameter is set to Y, the fragmentation level and page count is checked for each partition. The appropriate index maintenance (rebuild or reorganize) is then performed for each partition.

Value	Description
Y	Maintain partitioned indexes on the partition level.
N	Maintain partitioned indexes on the index level. This is the default.

TimeLimit

Set the time, in seconds, after which no commands are executed. By default, the time is not limited.

Indexes

Select indexes. If this parameter is not specified, all indexes are selected. The ALL_INDEXES keyword is supported. The hyphen character (-) is used to exclude indexes, and the percent character (%) is used for wildcard selection. All these operations can be combined by using the comma (,).

Value	Description
ALL_INDEXES	All indexes
Db1.Schema1.Tbl1.Idx1	The index Idx1 on the object Schema1.Tbl1 in the database Db1
Db1.Schema1.Tbl1.Idx1, Db2.Schema2.Tbl2.Idx2	The index Idx1 on the object Schema1.Tbl1 in the database Db1 and the index Idx2 on the object Schema2.Tbl2 in the database Db2
Db1.Schema1.Tbl1	All indexes on the object Schema1.Tbl1 in the database Db1
Db1.Schema1.Tbl1, Db2.Schema2.Tbl2	All indexes on the object Schema1.Tbl1 in the database Db1 and all indexes on the object Schema2.Tbl2 in the database Db2
Db1.Schema1.%	All indexes in the schema Schema1 in the database Db1
%.Schema1.%	All indexes in the schema Schema1 in all databases
ALL_INDEXES, -Db1.Schema1.Tbl1.Idx1	All indexes except the index Idx1 on the object Schema1.Tbl1 in the database Db1
ALL_INDEXES, -Db1.Schema1.Tbl1	All indexes except indexes on the object Schema1.Tbl1 in the database Db1

Delay

Set the delay, in seconds, between index commands. By default, there is no delay.

LogToTable

Log commands to the table dbo.CommandLog.

Value	Description
Y	Log commands to the table.
N	Do not log commands to the table. This is the default.

Execute

Execute commands. By default, the commands are executed normally. If this parameter is set to N, then the commands are printed only.

Value	Description
Y	Execute commands. This is the default.
N	Only print commands.

Examples

A. Rebuild or reorganize indexes with fragmentation on all user databases

EXECUTE dbo.IndexOptimize @Databases = 'USER_DATABASES',
@FragmentationLow = NULL,
@FragmentationMedium = 'INDEX_REORGANIZE,INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE',
@FragmentationHigh = 'INDEX_REBUILD_ONLINE,INDEX_REBUILD_OFFLINE',
@FragmentationLevel1 = 5,
@FragmentationLevel2 = 30

B. Rebuild or reorganize indexes with fragmentation and update modified statistics on all user databases

C. Update modified statistics on all user databases

EXECUTE dbo.IndexOptimize @Databases = 'USER_DATABASES',
@FragmentationLow = NULL,
@FragmentationMedium = NULL,
@FragmentationHigh = NULL,
@UpdateStatistics = 'ALL',
@OnlyModifiedStatistics = 'Y'

Execution

Execute the stored procedures from SQL Server Agent CmdExec jobs, using sqlcmd and the -b option. Pass the parameters to the stored procedures by name:
sqlcmd -E -S $(ESCAPE_SQUOTE(SRVR)) -d master -Q "EXECUTE dbo.IndexOptimize @Databases = 'USER_DATABASES'" -b
Use SQL Server Agent job output files with tokens for jobid, stepid, date, and time. Output files ensure that you always have a full set of information, in case of an error. Tokens ensure that the output files have unique file names.
You can use the MaintenanceSolution.sql script to install the SQL Server Maintenance Solution. Then the sqlcmd commands and the output files with tokens will be configured for you.

Getting Started

Download MaintenanceSolution.sql.
Execute MaintenanceSolution.sql. This script creates all the objects and jobs that you need.
Go into [SQL Server Agent] / [Jobs] and start the jobs that have been created. Verify that these jobs are completing successfully. Check the output files in the error log directory.
Schedule the jobs.

Upgrading

Download MaintenanceSolution.sql.
Change this line in the script so as not to create jobs:
SET @CreateJobs = 'N'
Execute MaintenanceSolution.sql. The script drops the old versions of the stored procedures and functions and creates new versions.
Start the jobs and verify that they are completing successfully.

fsugeiger

Wednesday, April 4, 2012

SQL Server Index and Statistics Maintenance