How do I run db2advis?
For dynamic SQL statements, the frequency with which statements are executed can be obtained from the monitor as follows:
- Issue the command: db2 reset monitor for database database-alias. Wait for an appropriate interval of time.
- Issue the command: db2advis -g other-options.
What is Db2 advisor?
The Db2® Design Advisor is a tool that can help you significantly improve your workload performance. The task of selecting which indexes, materialized query tables (MQTs), clustering dimensions, or database partitions to create for a complex workload can be daunting.
What is Db2?
The EXPLAIN statement obtains information about access path selection for an explainable statement . A statement is explainable if it is a SELECT, MERGE, TRUNCATE, or INSERT statement, or the searched form of an UPDATE or DELETE statement.
Can be used at the end to encourage index usage?
Use the % or the _ at the end to encourage index usage.
How do I optimize a query in DB2?
The 10 tips:
- Select only that which you need.
- Lock not, lest ye be locked.
- Avoid functions and conversions when possible – CHAR, UPPER, etc.
- Avoid Sorts.
- Avoid DISTINCT and ORDER BY when possible.
- In-lists are out.
- Ensure you are specifying the appropriate join predicates to avoid Cartesian joins.
How do I run a query in DB2?
The following steps summarize how to obtain information from EXPLAIN:
- Create the plan table. Before you can use EXPLAIN, you must create a plan table to hold the results of EXPLAIN.
- Populate the plan table. You can populate the plan table by executing the SQL statement EXPLAIN.
- Select information from the plan table.
What is optimize for 1 row in DB2?
OPTIMIZE FOR 1 ROW tells Db2 to select an access path that returns the first qualifying row quickly. Use FETCH FIRST n ROWS ONLY clause to limit the number of rows in the result table to n rows.
How do I see indexes in SQL?
To see the index for a specific table use SHOW INDEX: SHOW INDEX FROM yourtable; To see indexes for all tables within a specific schema you can use the STATISTICS table from INFORMATION_SCHEMA: SELECT DISTINCT TABLE_NAME, INDEX_NAME FROM INFORMATION_SCHEMA.
What is DB2 design advisor command?
db2advis – DB2 design advisor command The DB2® Design Advisor advises users on the creation of materialized query tables (MQTs) and indexes, the repartitioning of tables, the conversion to multidimensional clustering (MDC) tables, and the deletion of unused objects. The recommendations are based on one or more SQL statements provided by the user.
What does-m mean in db2advis-M pc?
For example, db2advis -m PC will recommend partitioning and MDC tables. If -m P or -m M are used in a partitioned database environment, the advise_partition table is populated with the final partition recommendation. The choice of possible values are:
What is the use of schema name in db2advis?
It serves as the schema name to use for CURRENT SCHEMA when db2advis executes. The default schema name is the user ID of the person executing the command. Specifies the name of a table space in which new MQTs will be created.