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 Related Questions An alias is an alternative to a synonym, designed for a distributed environment to avoid having to use the location qualifier of a table or view. The alias is not dropped when the table is dropped. Latest Answer : An alias is a logical pointer to an alternate table name. The purpose of an alias is to resolve loops in the paths of joins. In some cases, more than one alias may be necessary for a given table.Cheers,Sithu ... The simplest DB2 index is the B-tree and the B-tree's top page is called the root page. The root page entries represent the upper range limits of the index and are referenced first in a search. DB2 use the multiple indexes to satisfy multiple predicates in a SELECT statement that are joined by an AND or OR. A multiple index is not one index but two indexes for two different columns of a table. A composite index is one index made up of combined values from two columns in a table. If two columns in a table Latest Answer : if an index is created on more than one column ,which r frequently used in where clause of select statement. it will show the effect in increace in performance . ... The number of distinct values for a column is called index cardinality. DB2's RUNSTATS utility analyzes column value redundancy to determine whether to use a tablespace or index scan to search for For a clustered index DB2 maintains rows in the same sequence as the columns in the index for as long as there is free space. DB2 can then process that table in that order efficiently. Latest Answer : Clustered index is unique for any given table and we can have only one clustered index on a table. The leaf level of a clustered index is the actual data and the data is resorted in case of clustered index ... DB2 can implement a join in three ways using a merge join, a nested join or a hybrid join. Explain the differences. A merge join requires that the tables being joined be in a sequence; the rows are retrieved with a high cluster ratio index or are sorted by DB2. A nested join does not require a sequence and works best on joining a small number of rows. DB2 reads the outer table values and each time scans the inner table for matches. The hybrid join is a nested join that requires the outer table If there is an index on the attributes tested an IN is more efficient since DB2 uses the index for the IN. (IN for index is the mnemonic). Latest Answer : hi vipin sharma,IN subselects can also uesd in corelated sub queries.IN subselects needs to specify the vlues u want to search.EXISTS subselects doesn't need any to specify values . it searches ... They are the opposite of root pages. Leaf pages are the lowest level index pages - the pages that contain index entries and information to the corresponding table rows. Latest Answer : Leaf pages are used in context of indexes and contain data. ... The opposite of a leaf page; it is the highest level index page. An index can contain only the one root page; all other index pages are associated to the root.
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