TAILIEUCHUNG - OCA /OCP Oracle Database 11g A ll-in-One Exam Guide- P23

OCA /OCP Oracle Database 11g A ll-in-One Exam Guide- P23:There is an ever increasing demand for staff with IT industry certification. The benefits to employers are significant—they can be certain that staff have a certain level of competence—and the benefits to the individuals, in terms of demand for their services, are equally great. Many employers are now requiring technical staff to have certifications, and many IT purchasers will not buy from firms that do not have certified staff. | OCA OCP Oracle Database 11g All-in-One Exam Guide 176 LOBSEGMENT LOBINDEX LOB PARTITION If a column is defined as a large object data type then only a pointer is stored in the table itself a pointer to an entry in a separate segment where the column data actually resides. LOBs can have indexes built on them for rapid access to data within the objects and LOBs can also be partitioned. CLUSTER A cluster is a segment that can contain several tables. In contrast with partitioning which lets you spread one table across many segments clustering lets you denormalize many tables into one segment. NESTED TABLE If a column of a table is defined as a user-defined object type that itself has columns then the column can be stored in its own segment as a nested table. Every segment is comprised of one or more extents. When a segment is created Oracle will allocate an initial extent to it in whatever tablespace is specified. Eventually as data is entered that extent will fill. Oracle will then allocate a second extent in the same tablespace but not necessarily in the same datafile. If you know that a segment is going to need more space you can manually allocate an extent. Figure 5-2 shows how to identify precisely the location of a segment. In the figure the first command creates the table relying completely on defaults for the storage. Then a query against DBA_EXTENTS shows that the Figure 5-2 Determining the physical location of a segment s extents Chapter 5 Oracle Storage 177 segment consists of just one extent extent number zero. This extent is in file number 4 and is 8 blocks long. The first of the 8 blocks is block number 1401. The size of the extent is 64KB which shows that the block size is 8KB. The next command forces Oracle to allocate another extent to the segment even though the first extent is not full. The next query shows that this new extent number 1 is also in file number 4 and starts immediately after extent zero. Note that it is not clear from this .

TỪ KHÓA LIÊN QUAN
TAILIEUCHUNG - Chia sẻ tài liệu không giới hạn
Địa chỉ : 444 Hoang Hoa Tham, Hanoi, Viet Nam
Website : tailieuchung.com
Email : tailieuchung20@gmail.com
Tailieuchung.com là thư viện tài liệu trực tuyến, nơi chia sẽ trao đổi hàng triệu tài liệu như luận văn đồ án, sách, giáo trình, đề thi.
Chúng tôi không chịu trách nhiệm liên quan đến các vấn đề bản quyền nội dung tài liệu được thành viên tự nguyện đăng tải lên, nếu phát hiện thấy tài liệu xấu hoặc tài liệu có bản quyền xin hãy email cho chúng tôi.
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.