Tipos de Segmentos

B-Tree Index Index entry header Key column length Key column value ROWID Root Branch Leaf Index entry

Almacenamiento en los índices PCTFREE DB_BLOCK_SIZE-OVERHEAD-entries* ENTRY_ OVERHEAD-ENTRIES(directorio valores)-ROWID

Reescritura de Consultas

Function-Based Indexes SQL> CREATE INDEX FBI_UPPER_LASTNAME 2 ON CUSTOMERS(upper(cust_last_name)); SQL> SELECT * 2 FROM customers 3 WHERE UPPER(cust_last_name) = 'SMITH'; SQL> ALTER SESSION 2 SET QUERY_REWRITE_ENABLED = TRUE; SQL> ALTER SESSION 2 SET QUERY_REWRITE_ENABLED = enforced | trusted | stale_tolerated ;

Function-Based Indexes: Usage Function-based indexes:  Materialize computational-intensive expressions  Facilitate case-insensitive searches  Provide a simple form of data compression  Can be used for an NLS sort index

Índices y nulos Oracle ignora los registro donde todas las entradas son nulos. CREATE INDEX IDX1 ON EMPLOYEE(NVL(ename,’null’)

Ejemplo Bitmap- Tabla base

Ejemplo Bitmap (Bitmap Generado)

Ejemplo Consulta sobre Bitmap SELECT COUNT(*) FROM CUSTOMER WHERE MARITAL_STATUS = 'married' AND REGION IN ('central','west');

Bitmap Indexes key start ROWID end ROWID bitmap Table Index Block 10 Block 11 Block 12 File 3

Creating Bitmap Indexes CREATE BITMAP INDEX orders_region_id_idx ON orders(region_id) PCTFREE 30 STORAGE(INITIAL 200K NEXT 200K PCTINCREASE 0 MAXEXTENTS 50) TABLESPACE indx;

Comparing B-Tree and Bitmap Indexes B-tree Suitable for high-cardinality columns Updates on keys relatively inexpensive Inefficient for queries using OR predicates Useful for OLTP Bitmap Suitable for low-cardinality columns Updates to key columns very expensive Efficient for queries using OR predicates Useful for data warehousing

COMPUTE STATISTICS CREATE INDEX ord_customer_ix_demo ON orders(customer_id, sales_rep_id) COMPUTE STATISTICS;

Índices particionados localmente sobre tablas Particionadas CREATE TABLE employees (employee_id NUMBER(4) NOT NULL, last_name VARCHAR2(10), department_id NUMBER(2)) PARTITION BY RANGE (department_id) (PARTITION employees_part1 VALUES LESS THAN (11) TABLESPACE part1, PARTITION employees_part2 VALUES LESS THAN (21) TABLESPACE part2, PARTITION employees_part3 VALUES LESS THAN (31) TABLESPACE part3);

Índices Particionados Globalmente sobre Tablas Particionadas CREATE INDEX employees_global_part_idx ON employees(employee_id) GLOBAL PARTITION BY RANGE(employee_id) (PARTITION p1 VALUES LESS THAN(5000), PARTITION p2 VALUES LESS THAN(MAXVALUE));

Índices globales no particionados sobre tablas particionadas CREATE INDEX employees_global_idx ON employees(employee_id);

Hash-Partitioned Global Indexes: Overview 10g 1000,1001, … 900,901, … < 1000 < MAXVALUE 901,1001, … 900,1000, … Range-partitioned global index Hash-partitioned global index

Creating Hash-Partitioned Global Indexes SQL> CREATE INDEX ghoi_ix 2 ON order_items (order_id) GLOBAL 3 PARTITION BY HASH (order_id) ( 4 PARTITION p1 TABLESPACE tbs_1, 5 PARTITION p2 TABLESPACE tbs_2, 6 PARTITION p3 TABLESPACE tbs_3, 7 PARTITION p4 TABLESPACE tbs_4); SQL> CREATE INDEX ghoi_ix 2 ON order_items (order_id) GLOBAL 3 PARTITION BY HASH (order_id) 4 PARTITIONS 4 5 STORE IN (tbs_1, tbs_2, tbs_3, tbs_4);

Índices Bipmap para IOT Tabla de Correspondencia 9i  Hash, rango 10g  Lista ROWID FísicoROWID Lógico

Creación de una Tabla Particionada Organizada por Índice CREATE TABLE sales_range( salesman_id NUMBER(5), salesman_name VARCHAR2(30), sales_amount NUMBER(10), sales_date DATE, PRIMARY KEY(sales_date, salesman_id)) ORGANIZATION INDEX INCLUDING salesman_id OVERFLOW TABLESPACE tabsp_overflow PARTITION BY RANGE(sales_date) (PARTITION sales_jan2000 VALUES LESS THAN(TO_DATE('02/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p1_overflow, PARTITION sales_feb2000 VALUES LESS THAN(TO_DATE('03/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p2_overflow, PARTITION sales_mar2000 VALUES LESS THAN(TO_DATE('04/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p3_overflow, PARTITION sales_apr2000 VALUES LESS THAN(TO_DATE('05/01/2000','DD/MM/YYYY')) OVERFLOW TABLESPACE p4_overflow);