PostgreSQL-CE PGCES-02 問題集

質問 1：
PostgreSQL can use an index to access a table. Select two incorrect statements about indexes.
A. An index is created by 'CREATE INDEX', and deleted by 'DROP INDEX'.
B. By creating an index,performance always improves.
C. Creating an unused index does not affect the performance of a database at all.
D. By using an index effectively, searching and sorting performs faster.
E. There are B-tree, Hash, R-tree and GiST index types.
正解：B,C

質問 2：
You want to create a cursor that will SELECT the "customer" table. The created cursor must be able to move in any direction and reference data even after the end of the transaction.
Select one answer containing the correct keyword(s) to fill in the underlined blank below.
DECLARE cursor1 __________ FOR SELECT * FROM customer;
A. NO SCROLL CURSOR WITH HOLD
B. SCROLL CURSOR WITH HOLD
C. CURSOR WITHOUT HOLD
D. INSENSITIVE CURSOR
E. CURSOR
正解：B

質問 3：
Select two correct statements from below concerning the ANALYZE command.
A. It takes some time to execute, but it does not lock the table.
B. It renews the statistical information of the table content.
C. If ANALYZE isinsufficient, the most efficient search plan will not be selected for queries.
D. If the FULL option is used when executing, the size of the file can be reduced.
E. If ANALYZE is not used atall, there are times when it becomes impossible to see any of the data.
正解：B,C

質問 4：
Select one option which cannot be specified using createdb.
A. Host name
B. Character encoding
C. Template database
D. Database owner
E. Database locale
正解：E

質問 5：
What does the following command do? Choose one incorrect statement from the selection below. $ pg_dumpall -U postgres > 20060601.bak
A. Backup with plain-text format.
B. Backup user and group information along with databases.
C. You can access databases while the backup is in process.
D. Backup all the databases in a database cluster.
E. Backuppostgresql.conf along with databases.
正解：E

質問 6：
Select three SQL statements which return NULL.
A. SELECT 0 = NULL;
B. SELECTNULL != NULL;
C. SELECT NULL;
D. SELECT 'null'::TEXT;
E. SELECT NULL IS NULL;
正解：A,B,C