Oracle bitmap Index

Oracle indexes mainly include btree and bitmap indexes. By default, most btree indexes are used.
Unique index, clustering index, and so on. btree is used in OLTP to speed up query. The bitmap index is an interesting place in Oracle. It is mainly used in OLAP (online data analysis ).
It is used in data warehouse to speed up query and save storage space. Generally, indexes consume a large amount of storage space. Bitmap uses compression technology to reduce disk space.
Btree uses a high base (that is, a column with a large data similarity), and a bitmap is used in a low base series. The basic principle of Bitmap indexes is to use bitmaps instead of column values in indexes. Usually there is a very low key between a fact table and a dimension table.
Cardinality (cardinality), which uses Bitmap indexes for more effective storage. Compared with B * tree indexes, it only requires less storage space, so that more records can be read each time,
In addition, compared with B * tree indexes, bitmap indexes convert connections and aggregation into bitwise arithmetic operations, greatly reducing the running time and thus greatly improving the performance.

How can I reasonably use Bitmap indexes in Oracle? Consider the following.

* If you want to use Bitmap indexes, the initialization parameter star_transformation_enabled should be set to true.

* The optimization mode should be CBO. For data warehouse environments, you should always consider using CBO (COST-BASEDOPTIMIZER ).

* Bitmap indexes should be created on the foreign key columns of each fact table. (This is just a general rule .)

In addition, the objective determination of cardinality in the data table is also a problem. The 10 thousand data records only contain three values and are low. Therefore, the 0.1 billion records contain three
Ten thousand records are not low? In this case, we recommend that you perform a few data simulation tests. Generally, in the data warehouse environment, the bitmap index performance is better than the B * tree index. Also pay attention to bitmap
Indexes are not designed for OLTP databases. They should not be used in large quantities in OLTP databases, especially for tables with update operations.

Oracle indexes mainly include btree and bitmap indexes. By default, most btree indexes are used.
Unique index, clustering index, and so on. btree is used in OLTP to speed up query. The bitmap index is an interesting place in Oracle. It is mainly used in OLAP (online data analysis ).
It is used in data warehouse to speed up query and save storage space. Generally, indexes consume a large amount of storage space. Bitmap uses compression technology to reduce disk space.
Btree uses a high base (that is, a column with a large data similarity), and a bitmap is used in a low base series. The basic principle of Bitmap indexes is to use bitmaps instead of column values in indexes. Usually there is a very low key between a fact table and a dimension table.
Cardinality (cardinality), which uses Bitmap indexes for more effective storage. Compared with B * tree indexes, it only requires less storage space, so that more records can be read each time,
In addition, compared with B * tree indexes, bitmap indexes convert connections and aggregation into bitwise arithmetic operations, greatly reducing the running time and thus greatly improving the performance.

How can I reasonably use Bitmap indexes in Oracle? Consider the following.

* If you want to use Bitmap indexes, the initialization parameter star_transformation_enabled should be set to true.

* The optimization mode should be CBO. For data warehouse environments, you should always consider using CBO (COST-BASEDOPTIMIZER ).

* Bitmap indexes should be created on the foreign key columns of each fact table. (This is just a general rule .)

In addition, the objective determination of cardinality in the data table is also a problem. The 10 thousand data records only contain three values and are low. Therefore, the 0.1 billion records contain three
Ten thousand records are not low? In this case, we recommend that you perform a few data simulation tests. Generally, in the data warehouse environment, the bitmap index performance is better than the B * tree index. Also pay attention to bitmap
Indexes are not designed for OLTP databases. They should not be used in large quantities in OLTP databases, especially for tables with update operations.

Oracle indexes mainly include btree and bitmap indexes. By default, most btree indexes are used.
Unique index, clustering index, and so on. btree is used in OLTP to speed up query. The bitmap index is an interesting place in Oracle. It is mainly used in OLAP (online data analysis ).
It is used in data warehouse to speed up query and save storage space. Generally, indexes consume a large amount of storage space. Bitmap uses compression technology to reduce disk space.
Btree uses a high base (that is, a column with a large data similarity), and a bitmap is used in a low base series. The basic principle of Bitmap indexes is to use bitmaps instead of column values in indexes. Usually there is a very low key between a fact table and a dimension table.
Cardinality (cardinality), which uses Bitmap indexes for more effective storage. Compared with B * tree indexes, it only requires less storage space, so that more records can be read each time,
In addition, compared with B * tree indexes, bitmap indexes convert connections and aggregation into bitwise arithmetic operations, greatly reducing the running time and thus greatly improving the performance.

How can I reasonably use Bitmap indexes in Oracle? Consider the following.

* If you want to use Bitmap indexes, the initialization parameter star_transformation_enabled should be set to true.

* The optimization mode should be CBO. For data warehouse environments, you should always consider using CBO (COST-BASEDOPTIMIZER ).

* Bitmap indexes should be created on the foreign key columns of each fact table. (This is just a general rule .)

In addition, the objective determination of cardinality in the data table is also a problem. The 10 thousand data records only contain three values and are low. Therefore, the 0.1 billion records contain three
Ten thousand records are not low? In this case, we recommend that you perform a few data simulation tests. Generally, in the data warehouse environment, the bitmap index performance is better than the B * tree index. Also pay attention to bitmap
Indexes are not designed for OLTP databases. They should not be used in large quantities in OLTP databases, especially for tables with update operations.

Oracle indexes mainly include btree and bitmap indexes. By default, most btree indexes are used.
Unique index, clustering index, and so on. btree is used in OLTP to speed up query. The bitmap index is an interesting place in Oracle. It is mainly used in OLAP (online data analysis ).
It is used in data warehouse to speed up query and save storage space. Generally, indexes consume a large amount of storage space. Bitmap uses compression technology to reduce disk space.
Btree uses a high base (that is, a column with a large data similarity), and a bitmap is used in a low base series. The basic principle of Bitmap indexes is to use bitmaps instead of column values in indexes. Usually there is a very low key between a fact table and a dimension table.
Cardinality (cardinality), which uses Bitmap indexes for more effective storage. Compared with B * tree indexes, it only requires less storage space, so that more records can be read each time,
In addition, compared with B * tree indexes, bitmap indexes convert connections and aggregation into bitwise arithmetic operations, greatly reducing the running time and thus greatly improving the performance.

How can I reasonably use Bitmap indexes in Oracle? Consider the following.

* If you want to use Bitmap indexes, the initialization parameter star_transformation_enabled should be set to true.

* The optimization mode should be CBO. For data warehouse environments, you should always consider using CBO (COST-BASEDOPTIMIZER ).

* Bitmap indexes should be created on the foreign key columns of each fact table. (This is just a general rule .)

In addition, the objective determination of cardinality in the data table is also a problem. The 10 thousand data records only contain three values and are low. Therefore, the 0.1 billion records contain three
Ten thousand records are not low? In this case, we recommend that you perform a few data simulation tests. Generally, in the data warehouse environment, the bitmap index performance is better than the B * tree index. Also pay attention to bitmap
Indexes are not designed for OLTP databases. They should not be used in large quantities in OLTP databases, especially for tables with update operations.