1、从堆表(HeapTable)到索引组织表(IndexOrganization Table) Oracle作为一款成熟的数据库软件产品,就提供了多种数据表存储结构。我们最常见的就是三种,分别为堆表(Heap Table)、索引组织表(Index Organization Table,简称为IOT)和聚簇表(Cluster Table)。 Heap Table是我们在Oracle中最常使用的数据表,也是Oracle的默...
通过物理ROWID去访问IOT表就找不到数据。这个时候,Oracle会进行逻辑猜测,这时就不使用ROWID了,而是使用主键列的值去扫描IOT表。 创建IOT表的例子如下: create table iot_test(id number,c1 varchar2(40),c2 varchar2(40),c3 varchar2(40),c4 varchar2(40),primary key(id)) organization index tablespace ind...
Index-organized tables are useful when related pieces of data must be stored together or data must be physically stored in a specific order.This type of table is often used for information retrieval, spatial (see"Overview of Oracle Spatial"), andOLAPapplications (see"OLAP"). Index-Organized T...
(1)A heap-organized table does not store rows in any particular order. The CREATE TABLE statement creates a heap-organized table by default. (2)An index-organized table orders rows according to the primary key values. For some applications, index-organized ta...
In Oracle, an index-organized table (IOT) object is a special type of index/table hybrid that physically controls how data is stored at the table and index level. When you create a common database table or a heap-organized table, the data is stored unsorted, as a h...
An index-organized table differs from a heap-organized because the data is itself the index. See"Overview of Index-Organized Tables". Reverse key indexes In this type of index, the bytes of the index key are reversed, for example, 103 is stored as 301. The reversal of bytes spreads out...
The simplest explanation of an index-organized table is that it is accessed like any other Oracle table (typically a heap-organized table) but is physically stored like an Oracle B-tree index. Index-organized tables are typically created on “thin” tables (tables without too many columns). ...
Index-organized tables are useful when related pieces of data must be stored together or data must be physically stored in a specific order. This type of table is often used for information retrieval, spatial (see "Overview of Oracle Spatial" on page 19-14), and OLAP applications (see "OLA...
Bitmap indexes on index-organized tables are supported, provided the index-organized table is created with a mapping table. This is done by specifying the MAPPING TABLE clause in the CREATE TABLE state ...
Oracle Provider for OLEDB, see OraOLEDB, 13-2 ORaOLEDB AppendChunk(), 13-3 OraOLEDB, 3-15, 13-1, 13-2 GetChunk(), 13-3 P partitioned index-organized tables for LOBs, 5-30 restrictions for LOBs, 5-31 pattern check if it exists in BFILE using instr, 12-65 see ...