Sample reorg index control statements ibm knowledge center. Is there a dependence between reorg tables and reorg index. Db2 calling reorg command from jdbc technical advices. As part of maintenance procedure, we are deleting huge data from our db2 database. The answer to your question appears to be in the sysstat. The function is on a lob column for example, an index on an inline lob column. Sortdata no is specified, or no index is defined on the data that is being reorganized. A few index holes are good, into which newly inserted rows can go. In some cases, the only changes that you make in a work id can be accomplished by using alter statements and online reorganizations for example, online schema changes. Timestamp of the last reorg index on the index space or partition.
The number of rows in the mapping table whould not exceed 110% of the rows in the table space or partition to be reogranized. The table space is in advisory reorgpending status as the result of an alter table statement. Realistically, db2 supports only a btree style of index. Tables defined using the organize by clause and the corresponding dimension indexes have a suffix to their names. When an insert happens, db2 finds the candidate page affected. On index creation, loads and reorgs, db2 reserves empty space for future inserts on every leaf page. When indexed columns are updated frequently, then the index for the table has to be created again. An upper or lower function has any of the following characteristics. After a successful online reorg, shrlevel change, with inline backup on db2 9 for zos, is there a reason why it ends with a return code 4 instead of return code 0. I m searching an appropriate solution to reorganize a table when it s altered, or reorganize all the schema after making various modifications.
The logged data for the offline reorg is very small compared to the work necessary to complete. The remedy for this kind of fragmentation is index reorganization. If you specify the minpctused option on the create index statement, the. Db2 luw reorg index space reclaimed february 26, 2014 02. You will need to run the reorg command usually after executing the alter table drop column statement. If there isnt any room for an additional row to fit, db2 will split the page into two equal groups. So if i do a reorg table, will that automatically reorg the indexes. So if i do a reorg table, will that automatically reorg the indexes on that table or are the indexes completely separate. The example shows a potential performance problem that could occur by running an offline reorg for a large table on the primary database.
The reorg balances the index btree and puts all of the index entries into contiguous space. The goal is to resolve any out of bounds indicators using the least system resources. This email transmission contains information that is confidential and may be privileged. How to reorg index in db2 solutions experts exchange. This principle is backed up in the recent bestselling book. Db2 utilities either execute within the subsystem online or standalone and run outside the subsystem offline.
There are three methods of reorganizing your database. Before using this information and the product it supports, read the information in notices on. When i alter a table in db2, i have to reorganize it so i execute the next query call sysproc. Dsn8s81d and to use a parallel index build to rebuild the indexes. The reorg indexestable command reorganizes an index or a table. Reorg is needed whenever indexed columns are updated frequently.
Indexes on expression documentation for reorg plus for. A deferred index is an empty index structure that can be populated at a later date. Updating access path statistics in the catalog and catalog history tables while reorganizing an index. As time goes by, inserts add entries whereas delete pseudodeletes the index entries and leaves holes.
Although db2 is always collecting rts data, nothing is externalized until you set up the rts database and tables to store the real time statistics. Since the data in the table doesnt move, everything in the index is technically correct, its just not organized in the most efficient fashion and db2 doesnt need to read the table data. The amount of space required is determined by the number of rows being reorganized, the number of indexes, the size of the index keys. Db2 reorg from the view of application developer novatec. The activities performed by the utilitiesloading and reorganizing data, recovering data and indexes, rebuilding indexes, gathering statistics, quiescing data, and repairing dataare discussed in detail in chapters 7 and 8. Find a best practice for integrating technologies in ibm redbooks explore, learn. Tables that have been modified so many times that data is fragmented and access performance is noticeably slow are candidates for reorganization. Db2 reorg tables and reorg indexes solutions experts. Reorganizing a table and using parallel index build the following reorg tablespace statement specifies that the utility is to reorganize table space dsndb04. In this entry, im going to talk about how to determine what kind of reorg is needed on what tables. There are other types you might hear about like block indexes for mdc tables, but they are only used in special situations. The actions for reorganizing tables are listed on the action pad.
No data will be sorted during the reorg tablespace job. The log space required for an online table reorg is typically larger than what is required for an offline table reorg. Use option 1, run db2 reorg utility, from the utilities pulldown on the tablespace list window, shown. It can also help move data that is related closer to each other for more efficient access especially true in the case of a cluster index.
Db2 10 utilities sample reorg index control statements. The following table describes the behavior of keepdictionary syntax in reorg. Reorg is a database operation that is executed in db2 to reorganize the table spaces or index spaces. Verification of this requires a sanity check that i can not do for you as i do not use db2 luw. Dsnaccox recommends reorg on the index when on the following conditions is true and reorg or all is also specified for the value of querytype the index is in reorgpending status.
The reorganisation of an object necessarily consists of the destruction of an object and its rebuilding in reorganised form. After an index is physically created after running extensive updates, deletions, or insertions in a table space after running any of the following utilities without collecting inline statistics. The following control statement specifies that reorg tablespace is to reorganize table space dsndb04. Indexindex fields,so that the system can access records easily thru which the access cost will come down. This operation reconstructs the data in the table spaces or index spaces, so that the data is unfragmented and physically continuous.
The reorg index utility control statement, with its multiple options, defines the function that the utility job performs. Reorganization of tables db2 udb for unix and windows use. So using reorg command is ran, it physically deletes the record from db. If any of the table formulas are out of bounds, these are the f1, f2 and f3, then a full table and index reorganization would be required. Here is an example checking whether any activity has occurred in the past ten days for a table space just supply the table. The following control statement specifies that while reorganizing index iu0e0801, reorg index is to collect statistics and update access path statistics in the catalog and catalog history tables. The following formulas help you estimate the sizes for the work data sets required by the check index utility. When should the db2 catalog and directory be reorganized.
The reorg table command reorganizes a table by reconstructing the rows to. The query reorg table table returns an unexpected token table was found following reorg. Reorganization of tables db2 udb for unix and windows. Reorg is used to help db2 point to accurate data ie, indexes should become aware of fresh data and no longer include deleted data, as well as collapse empty page space created by deletion of data andor indexes. The locale name has a value other than uni or blank. Specify the most important index for reorg sequencing. Btw you can configure db2 to automatically run runstats or reorg as needed by changing appropriate db config parameters. The number of index entries that have been inserted since the last reorg, rebuild index or load replace on the index space or partition that have a key value that is greater than the maximum key value in the.
You can parallel run a reorg on a partitioned table index as long as the first, and subsequent runnings do not allow reads. I am new to db2 and have noticed that a certain db2 database will not backup as well as when i connect to the database using control center under health it is reporting that a reorg is needed. The column contains mixed or dbcs data, and the locale name is. Pctfree, a percentage of the pagesize reserves space for row overflows on all leaf pages. The diagram below shows what the structure of a btree index looks like. Through the use of case studies and examples gladwell introduces us to the power of. Recover tablespace, rebuild index, or reorg tsix before running reorg with the offposlimit, indreflimit, or leafdistlimit options. I will have a future blog entry to discuss index reorgs in detail. The following control statement specifies that the reorg index utility is to. You can use the dba planning calendar to schedule a reorganization of a set of tables. There is controversy in the db2 community on what criteria to use to decide when to reorg. If you do not have a clustering index on a table, you can still use reorg to order the data in the order of any index, simply by specifying it in the reorg command. The onlineoffline maintenance window configuration determines when db2 auto reorg can execute maintenance tasks.
Sometimes, you need to run the db2 reorg command from the jdbc code. Reorgs are one critical piece of both performance maintenance and maintaining how much disk space is used. I will have a future blog entry to discuss index reorgs in. Restriction online index reorganization is not supported in db2 purescale environments and will fail with sql1419n. The output from reorg index consists of a reorganized index or index partition. The cardinality of a dimension index is equal to the active blocks statistic of the table. Say, pctfree10 of a 4k page books 400 bytes on every leaf.
When to use cleanup only or cleanup only pages on reorg utility. After deleting data, can i execute the below scripts to remove white space and rebuild indexes. How much log space is requeried during an online reorg. In order to execute the reorg command from jdbc, you can do this as follows call sysproc. For example, if precomputed view maintenance is set to off in your application, you can use the reorg command to rebuild precomputed views only, without touching the indexes on the target table. The table space is in advisory reorg pending status as the result of an alter table statement. Reorganizing a table while allowing readwrite access. Dsnaccox recommends reorg on the index when on the following conditions is true and reorg or all is also specified for the value of querytype the index is in reorg pending status. Online reorg is an availability enhancement to db2 introduced in db2 version 5. More complex and precise calculations can be found in the db2 utility guide and reference manual, but these formulas should produce comparable results. Restriction online index reorganization is not supported in db2 purescale. Before using this information and the product it supports, read the information in notices on page xxvii. This two statement operation allocates a new set of index pages which are roughly.
This edition applies to version 11, release 1 of db2 for zos program number 5615db2 and version 11, release 1 of db2 utilities suite for zos program number 5655w87. Reor ibm reorg utility documentation for alter and. The purpose of the reorganization is data clustering. Jan 14, 2017 the onlineoffline maintenance window configuration determines when db2 auto reorg can execute maintenance tasks. Syntax and options of the reorg tablespace control statement. Db2 reorg tables and reorg indexes solutions experts exchange. We hope that the new structure will help you quickly find the content that you need. The number of index entries that have been deleted since the last reorg, rebuild index, or load replace on the index space or partition.
Reorganizing the db2 catalog and directory be reorganized. To reorganize the employee table using the temporary table space tempspace1 as a work area, enter. Find a technical tutorial in ibm developer find a best practice for integrating technologies in ibm redbooks explore. Based on the newly inserted rows key, an index hole may be reused, otherwise its added to the overflow area. The check index option db2 developers guide 5th edition.
All reorg jobs except reorg and runstats for single table are only available if the automatic reorg by db2. One for zos on mainframes, one for ibm i on power systems, and one for linux, unix, windows luw. Jun 02, 2014 an asterisk indicates that a table reorg is needed for that table, based on the results of that specific query. Find an index with a sigle fixed key column and compare that column widith to avgleafkesize. The content is now organized based on logical branches instead of legacy book titles. Db2 maintenance script runstats, reorg posted on april 11, 20 march 3, 2017 by daharveyjr i had a local copy of a websphere commerce database that was performing horribly, and i decided to create a script that would retrieve a list of all available tables for all nonsystem schemas, and perform a runstats and reorg for those tables. What is a reorg, i talked about some purposes of reorgs.
If you do this, db2 makes no attempt to maintain the table data in the order of the index it is only on reorg that this is done. Indexes on expression documentation for reorg plus for db2. No offline activities are executed by db2 auto reorg if you use the auto reorg policy recommended by sap. Appendix h reorganizing the db2 catalog p rior to db2 v4, it was not possible to reorganize the table spaces in the db2 catalog and db2 directory because of the internal hash and link structures built into these databases. Utility that rebuilds and compresses the physical structure of indexes. Use option 1, run db2 reorg utility, from the utilities pulldown on the tablespace list window, shown in figure 38. Copyddn ddname1,ddname2 specifies the dd statements for the primary ddname1 and backup ddname2 copy data sets for the image copy. Dsn8s81e and to use a parallel index build to rebuild the indexes. Apr 11, 20 db2 maintenance script runstats, reorg posted on april 11, 20 march 3, 2017 by daharveyjr i had a local copy of a websphere commerce database that was performing horribly, and i decided to create a script that would retrieve a list of all available tables for all nonsystem schemas, and perform a runstats and reorg for those tables. Index cleanup and space reclaim from tables and indexes are executed during the online maintenance window.
When reorg is run on an index, db2 reorganizes the index space to. It increases availability of a tablespace andor index while it is being reorganised. Db2 reorgs need the current runstats on the table to be correct to give the correct results for the reorganisation identifying stored procedure. Aug 27, 2012 btw you can configure db2 to automatically run runstats or reorg as needed by changing appropriate db config parameters. The results of the reorgchk calculations show what type of table or index reorganization might be needed. Also when asking db management issues for db2, please specify which db2 you are asking about. But for db2 v4 and later releases, you can expediently reorga. The previous db2 admin has a maintenance script setup for run once with a command script of.
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