For example: PL/SQL lets you use all SQL data manipulation, cursor control, and transaction control statements, and all SQL functions, operators, and pseudocolumns. SQL> create index t_idx_1 on t(owner,object_type,object_name); Index.
2>Should one consider the clustering factor while desiging a composite index, and desgin.
You are strongly encouraged to use this index type for all new spatial indexes you create, regardless of whether the spatial table or the spatial index is partitioned, and you may also want to use it if you decide to re-create legacy spatial indexes.
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MySQL cannot use a composite index in a lookup in which the WHERE condition doesn't include the columns forming a left-most prefix:.
Try and establish your usage patterns and index accordingly.
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The following shows the syntax of creating a function-based index: CREATE INDEX index_name ON table_name (expression).
SQL> update t2 2 set b=900 3 where b = 6; -- update primary key without 'exec update_cascade.
They provide faster.
A composite index, also called a concatenated index, is an index on multiple columns in a table.
PL/SQL is tightly integrated with SQL, the most widely used database manipulation language.
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columns and i have an index on a,b columns! There is a sql statement now with where a= ? and we are wondering if it could also be good to add a single index on just 'a' column!.
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2>Should one consider the clustering factor while desiging a composite index, and desgin.
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In the case of (item_type, item ), oracle will correctly calculate cardinalities for queries with item types A and B, but for "item_type='C' and item=:X" it can underestimate.