What are the commonly used table types in Oracle?

The following table types are commonly used in oracle:

1.Heap table: When data is stored, rows are out of order, and access to it is scanned by the whole table.

2.Partition table table "2g".

3.Index Organizational Tables (IoT).

4.Cluster table. 5.Temporary tables.

6.Compress the table.

7.Nested tables.

The core of Oracle Database is tables, and the common data types used by the columns in tables are as follows:

Example of the corresponding number type:

For date types, you can use the sysdate built-in function to get the current system date and time, return the date type, and use the systimestamp function to return the current date, time, and time zone.

There are many ways to join multiple tables in Oracle:

1. There are three ways to join a table: nested loop, hash join, and sort merge join.

2. Nested loop is a loop nested connection method, for the connected subset is relatively small, nested loop is a better choice. In nesting, the inner table is driven by the outer table, the outer table does a loop, and the inner table loops to each row of the outer table.

3. The return result set of this kind of table should not be too large, otherwise it will be too inefficient, and it must be used when the table has indexes.

4. Sort Merge Join is used when the data does not have an index, and the data must be all sort numbers.

5. In short, the connection between the two tables will choose different connection methods according to the different situations between the tables, the connection is actually to do the traversal of each row of data between the tables, even before you have to prepare, there is no index, either use the sorted number of the table, or use the hash algorithm, there is no pure traversal loop that does not prepare anything.

6. The premise of using three kinds of connections, when the tables are sorted numbers, use sort merge join to connect, when the two tables are about the same size and both have indexes, use nested loop to connect, when there is no index and no sorting, and the amount of data is large, use this hash algorithm to connect.

According to the storage method of index data, indexes can be divided into: b-tree index, bitmap index, inverse key index, and function-based index.

According to the uniqueness of index columns, they can be divided into: unique indexes and non-unique indexes.

According to the number of index columns, it can be divided into: single-column index and compound index.

1.B-tree index.

The most common type of index in Oracle databases is the B-Tree index, also known as the B-Tree Index, named after the computational science structure of the same name. create

When you make an index statement, you are creating a b-tree index by default. There are no special provisions that can be used in any situation.

2.Bitmap index

Bitmap indexes are specific to cases where the column has only a few enumerated values, such as a gender field, and a flag field such as only 0 and 1.

3.Function-based indexes.

For example, when you often query a certain field, you can use a function to operate, so it is valuable to create a function index.

SQL Developer: Officially produced by Oracle, the advantages are: accurate bookmarks, which can be easily set and switched; Auto-capitalization keywords; filter table fields; Easy to copy rows.

SQL Developer: An integrated development environment dedicated to the development of program units for Oracle database storage.

Charging tools. Precise bookmarks, auto-capitalization keywords, configurable smart hint range, grammar error correction, and more.

Enterprise Manager, graphical data management.

Oracle's commonly used stress testing tool: orastress.

It can test the CPU or memory pressure of the database (in read-only mode), and can also test the I-O capability of the database in two ways: normal insert and direct path insert. However, Orastress can only run on Windows, but it can test the stress of a remote server.