Oracle Database Interview Question:

What Happens to the Indexes If a Table Is Recovered?

Submitted by: Administrator

If you dropped a table, and recovered it back from the recycle bin, what happens to its indexes? Are all indexes recovered back automatically? The answer is that all indexes will be recovered, if you recover a dropped table from the recycle bin. However, the indexes' names will not be the original names. Indexes will be recovered with the system assigned names when they were dropped into the cycle bin. The following SQL script shows you this behavior:

ALTER SESSION SET recyclebin = on;
Statement processed.

CREATE TABLE student (id NUMBER(5) PRIMARY KEY,
first_name VARCHAR(80) NOT NULL,
last_name VARCHAR(80) NOT NULL,
birth_date DATE NOT NULL,
social_number VARCHAR(80) UNIQUE NOT NULL);
Table created.

CREATE INDEX student_birth_date ON student(birth_date);
Index created.

SELECT index_name, table_name, uniqueness
FROM USER_INDEXES WHERE table_name = 'STUDENT';
<pre>INDEX_NAME TABLE_NAME UNIQUENES
----------------------- --------------------- ---------
SYS_C004141 STUDENT UNIQUE
SYS_C004142 STUDENT UNIQUE
STUDENT_BIRTH_DATE STUDENT NONUNIQUE</pre>
DROP TABLE student;
Table dropped.
Submitted by: Administrator

SELECT index_name, table_name, uniqueness
FROM USER_INDEXES WHERE table_name = 'STUDENT';
no data found

FLASHBACK TABLE student TO BEFORE DROP;
Flashback complete.

SELECT index_name, table_name, uniqueness
FROM USER_INDEXES WHERE table_name = 'STUDENT';
<pre>INDEX_NAME TABLE_NAME UNIQUENES
------------------------------ ---------- ---------
BIN$K47Sg+udQv2tDUW5cWAIrQ==$0 STUDENT UNIQUE
BIN$6WI0gc79QNqLSNGp2H2Q1Q==$0 STUDENT UNIQUE
BIN$9HwZermkRt+9gonHS/klsQ==$0 STUDENT NONUNIQUE</pre>
If you have trouble running the FLASHBACK statement on your Web interface, run it with SQL*Plus.
Submitted by: Administrator