Important Views in Oracle DB

1. dba_tablespaces
SQL> desc dba_tablespaces;
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 TABLESPACE_NAME                           NOT NULL VARCHAR2(30)
 BLOCK_SIZE                                NOT NULL NUMBER
 INITIAL_EXTENT                                     NUMBER
 NEXT_EXTENT                                        NUMBER
 MIN_EXTENTS                               NOT NULL NUMBER
 MAX_EXTENTS                                        NUMBER
 MAX_SIZE                                           NUMBER
 PCT_INCREASE                                       NUMBER
 MIN_EXTLEN                                         NUMBER
 STATUS                                             VARCHAR2(9)
 CONTENTS                                           VARCHAR2(9)
 LOGGING                                            VARCHAR2(9)
 FORCE_LOGGING                                      VARCHAR2(3)
 EXTENT_MANAGEMENT                                  VARCHAR2(10)
 ALLOCATION_TYPE                                    VARCHAR2(9)
 PLUGGED_IN                                         VARCHAR2(3)
 SEGMENT_SPACE_MANAGEMENT                           VARCHAR2(6)
 DEF_TAB_COMPRESSION                                VARCHAR2(8)
 RETENTION                                          VARCHAR2(11)
 BIGFILE                                            VARCHAR2(3)
 PREDICATE_EVALUATION                               VARCHAR2(7)
 ENCRYPTED                                          VARCHAR2(3)
 COMPRESS_FOR                                       VARCHAR2(12)



Common Usage:
SQL> select TABLESPACE_NAME from dba_tablespaces where TABLESPACE_NAME='HSS';

TABLESPACE_NAME
------------------------------
HSS

SQL> select TABLESPACE_NAME from dba_tablespaces where TABLESPACE_NAME='EAS';

no rows selected
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