The EXPLAIN statement obtains information about access path selection for an explainable statement. A statement is explainable if it is a SELECT, MERGE,

Explain name of DB2 subsytem that executed EXPLAIN: SECTNOI: INTEGER: Section number of the statement: EXPANSION_REASON: CHAR(2) Applies to only statements that reference archive tables or temporal tables. For other statements, this column is blank.

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Explain db2

Whenever we want to tune a query, we need to go and check the plan table so as to get an idea of the access path DB2 optimizer is using. The previous sections used the explain tool to examine DB2 access plans. The next sections will introduce the db2exfmt tool and discuss how to interpret its output. The db2exfmt tool reads the explain tables and builds an ASCII report with the explain information, as … 2012-01-18 The Explain command details the access path defined by DB2 and allows you to analyze how the data will be accessed and how you can improve the command’s performance.

Query. 1. Tables.

An alternative to issuing dynamic EXPLAIN statements is to use a combination of the CURRENT EXPLAIN MODE and CURRENT EXPLAIN SNAPSHOT special registers to explain dynamic query statements. The EXPLAIN statement should be used when it is advantageous to set the QUERYNO or QUERYTAG field at the time of the actual EXPLAIN invocation.

Statistics 4. Configuration Parameters 8. Explain Snapshot Visual Explain This tutorial contains lessons on: v Creating explain snapshots. These are requirements for displaying access plan graphs.

22 Oct 2013 Optimize DB2 Query Using Explain Tool. DB2 has various tools that will show you how it goes about executing a SQL statement. I like the

I do 99% of everything with DB2 databases from a command line. For DB2/UDB, explain tables can be written to the SYSTOOLS schema rather than your own schema.

Steen Rasmussen, CA inc. DB2/UDB comes with some very good tools for analysing plan information, in particular the Visual Explain tool which is available in the Control Center. AQT’s plan analysis is not designed to replace this tool, but to provide a quick display of basic plan information. EXPLAIN is a very typical thing. it gives you the following information.
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Explain Snapshot Visual Explain This tutorial contains lessons on: v Creating explain snapshots. These are requirements for displaying access plan graphs. I installed IBM - DB2 Express Server Edition and I'm trying to run an EXPLAIN statement on a query.

If the user has DBADM authority, or the database registry variable DB2_VIEW_REOPT_VALUES is set to YES, the EXPLAIN_PREDICATE table will also be populated with the values if they are used to reoptimize the statement. 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. Explanation on DB2 Explain.
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Engage in lectures and hands-on labs to gain experience to: Relate the z/OS IPL process to a DB2 subsystem Explain effects of stopping and starting

2012-01-18 · Explanation on DB2 Explain. When an SQL is executed against or bound to a DB2 database, DB2 Optimizer tool defines the access path used to access the data. This access path is defined according to tables’ statistics generated by DB2 Runstats tool. The Explain command details the access path defined by DB2 and allows you to analyze how the data will EXPLAIN statement.

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When EXPLAIN STMTCACHE is issued together with STMTID xxxx, where "xxxx" could be an integer value, as shown in my red-highlighted example, above, or a host variable into which a statement ID had been placed, what Db2 provides is the access path information that was generated for the statement associated with the ID (and statement ID is part of what you get in the output of EXPLAIN STMTCACHE

The db2exfmt tool reads the explain tables and builds an ASCII report with the explain information, as … 2012-01-18 The Explain command details the access path defined by DB2 and allows you to analyze how the data will be accessed and how you can improve the command’s performance. A table called PLAN_TABLE which has your user id as its owner is required for working on DB2 Explain. You can create it … 2019-04-01 It signifies a position in the DB2 LOG. Generally RBA will be mapped to a timestamp. I mean RBA is nothing but a timestamp.