The course is updated for DB2 10 for z/OS. This course is the classroom delivered version of the Instructor led Online course DB2 10 for z/OS System Administration - ILO (3V851).. Administrators of DB2 10 for z/OS can acquire a view of the architecture and fundamental processes required to manage a DB2 10 for z/OS subsystem.

This entry was posted in DB2, Mainframe and tagged DB2 Predicates, Indexable Predicate, Non Indexable Predicate, Performance Tuning DB2 Queries, Performance Tuning SQL Queries, Stage 1 Predicates, Stage 2 Predicates. Bookmark the permalink. Post navigation ←

6. Db2 creates EXPLAIN output and populates EXPLAIN tables in the following situations: When an EXPLAIN statement is executed. At BIND or REBIND with the EXPLAIN(YES) or (ONLY) bind options. Rows are added for every explainable statement in the plan or package being bound. EXPLAIN indicates whether DB2 used an index to access data, whether sorts were performed, whether parallel processing was used, and so on. As you gain experience working with DB2, you can use the plan table to give optimization hints to DB2 that influence access path selection. For joins of tables, EXPLAIN indicates the join method and type, the order in which Db2 joins the tables, and the occasions when and reasons why it sorts any rows.

Also, This DB2 tutorial will be helpful to mainframe programmer to increase their level of expertise in DB2. DB2 is a product of IBM and most of the time it runs on IBM mainframes. we use this in assembly language that is AS400 Or runs in Linux environment. Note We can also download DB2 to the local PC and we can install it, but this tutorial primarily focuses on DB2 on IBM mainframes. We can go to Wikipedia and see details about IBM DB2. You can use the DB2 EXPLAIN statement to determine the access paths for the SELECT parts of your statements. DB2 EXPLAIN helps you answer questions about Query Performance & Query Optimization; the answers give you the information that you need to make performance improvements.

Output from EXPLAIN: DB2 inserts one or more rows of data into a plan table and other existing EXPLAIN tables. For a list of all EXPLAIN tables, see EXPLAIN tables. A plan table must exist before the operation that results in EXPLAIN output. You can find a sample CREATE TABLE statement for each EXPLAIN table in member DSNTESC of the prefix.

A table called PLAN_TABLE which has your user id as its owner is required for working on DB2 Explain. You can create it by using the below SQL. Db2 creates EXPLAIN output and populates EXPLAIN tables in the following situations: When an EXPLAIN statement is executed. At BIND or REBIND with the EXPLAIN(YES) or (ONLY) bind options.

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Rows are added for every explainable statement in the plan or package being bound.
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If we Quiesce on a tablespace, DB2 will put a enry in SYSCOPY with the RBA and a entry in DB2 directory. so that they will be used as recovery points if needed. RBA is called as LRSN in data sharing environment. But concept of LRSN and RBA are same.

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Say, DB2 is going to execute that query you have given, through that index. Today you or someone who has authority deletes that index. When u execute the query tomorrow it will not take the plan that has already created. DB2 automatically rebinds during the execution of the query, since the index is marked incorrect.

Db2 creates EXPLAIN output and populates EXPLAIN tables in the following situations: When an EXPLAIN statement is executed. At BIND or REBIND with the EXPLAIN(YES) or (ONLY) bind options. Rows are added for every explainable statement in the plan or package being bound. EXPLAIN indicates whether DB2 used an index to access data, whether sorts were performed, whether parallel processing was used, and so on.

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This entry was posted in DB2, Mainframe and tagged DB2 Predicates, Indexable Predicate, Non Indexable Predicate, Performance Tuning DB2 Queries, Performance Tuning SQL Queries, Stage 1 Predicates, Stage 2 Predicates. Bookmark the permalink. Post navigation ←

5. All the information about the user-defined functions used. 6. Db2 creates EXPLAIN output and populates EXPLAIN tables in the following situations: When an EXPLAIN statement is executed. At BIND or REBIND with the EXPLAIN(YES) or (ONLY) bind options. Rows are added for every explainable statement in the plan or package being bound.

What you're looking for is covered by two DB2 utilities: The explain utility, which shows the optimizer's access plan and estimated cost for a specific query (based on current RUNSTATS statistics) The design advisor, which recommends structural changes to improve the performance of one or more queries

it gives you the following information. 1. Whether the DB2 has made use of index, and if yes which all indexes. 2. Whether a join criteria satisfied in the table. 3.

A Complete Reference for Mainframe Programmer. Get Started Audience: DB2 tutorial will be useful for anyone, be in a student, a software Engineer or anyone who is serious towards mastering the DB2 in Mainframe. Also, This DB2 tutorial will be helpful to mainframe programmer to increase their level of expertise in DB2. DB2 is a product of IBM and most of the time it runs on IBM mainframes. we use this in assembly language that is AS400 Or runs in Linux environment. Note We can also download DB2 to the local PC and we can install it, but this tutorial primarily focuses on DB2 on IBM mainframes. We can go to Wikipedia and see details about IBM DB2. You can use the DB2 EXPLAIN statement to determine the access paths for the SELECT parts of your statements.