dba_segments描述为数据库中的所有段分配的存储空间。

user_segments描述为当前用户的对象所拥有的段分配的存储。此视图不显示owner、HEADER_FILE、HEADER_BLOCK或RELATIVE_FNO列。

Column	Datatype	NULL	Description
OWNER	VARCHAR2(30)		Username of the segment owner 段的拥有者
SEGMENT_NAME	VARCHAR2(81)		Name, if any, of the segment 段的名称
PARTITION_NAME	VARCHAR2(30)		Object Partition Name (Set to NULL for non-partitioned objects) 分区表对应段的名称
SEGMENT_TYPE	VARCHAR2(18)		Type of segment: * NESTED TABLE * TABLE * TABLE PARTITION * CLUSTER * LOBINDEX * INDEX * INDEX PARTITION * LOBSEGMENT * TABLE SUBPARTITION * INDEX SUBPARTITION * LOB PARTITION * LOB SUBPARTITION * ROLLBACK * TYPE2 UNDO * DEFERRED ROLLBACK * TEMPORARY * CACHE * SPACE HEADER * UNDEFINED 段的类型
SEGMENT_SUBTYPE	VARCHAR2(10)		Subtype of LOB segment: SECUREFILE, ASSM, MSSM, and NULL LOB段的子类型:SECUREFILE、ASSM、MSSM和NULL
TABLESPACE_NAME	VARCHAR2(30)		Name of the tablespace containing the segment 包含段的表空间的名字
HEADER_FILE	NUMBER		ID of the file containing the segment header 表示这个段的头在哪个数据文件里，因为段可以跨数据文件。
HEADER_BLOCK	NUMBER		ID of the block containing the segment header 表示这个段的头在数据文件的第几个 block里
BYTES	NUMBER		Size, in bytes, of the segment 段的大小，默认：bytes
BLOCKS	NUMBER		Size, in Oracle blocks, of the segment 段占了多少个块
EXTENTS	NUMBER		Number of extents allocated to the segment 分配了多少个 extent
INITIAL_EXTENT	NUMBER		Size in bytes requested for the initial extent of the segment at create time. (Oracle rounds the extent size to multiples of 5 blocks if the requested size is greater than 5 blocks.) 在创建时为段的初始区段请求的大小(以字节为单位)。(如果请求的大小大于5个块，Oracle将区段大小舍入为5个块的倍数。)
NEXT_EXTENT	NUMBER		Size in bytes of the next extent to be allocated to the segment 下一个分配的 extent 大小（以 byte 计）。如果为空表示是自动分配
MIN_EXTENTS	NUMBER		Minimum number of extents allowed in the segment 最少分配多少个 extent（以个数计）
MAX_EXTENTS	NUMBER		Maximum number of extents allowed in the segment 最多分配多少个 extent（以个数计）
MAX_SIZE	NUMBER		Maximum number of blocks allowed in the segment 最多分配多少个 blocks 大小
RETENTION	VARCHAR2(7)		Retention option for SECUREFILE segment 安全段的保留选项
MINRETENTION	NUMBER		Minimum retention duration for SECUREFILE segment 对于 securefile 段最小保持时间
PCT_INCREASE	NUMBER		Percent by which to increase the size of the next extent to be allocated 下一次 extent 分配增长的百分比
FREELISTS	NUMBER		Number of process freelists allocated to this segment 指定了所有可用于 insert 操作的数据块的列表，管理 HWM 以下的空闲空间
FREELIST_GROUPS	NUMBER		Number of freelist groups allocated to this segment 为此段分配的空闲列表组数
RELATIVE_FNO	NUMBER		Relative file number of the segment header 段头的相对文件号
BUFFER_POOL	VARCHAR2(7)		Buffer pool to be used for segment blocks: DEFAULT KEEP RECYCLE Buffer pool 中段所使用的 blocks
FLASH_CACHE	VARCHAR2(7)		Database Smart Flash Cache hint to be used for segment blocks: DEFAULT KEEP NONE Solaris and Oracle Linux functionality only. 数据库 Smart Flash Cache 提示段 blocks 方式
CELL_FLASH_CACHE	VARCHAR2(7)		Cell flash cache hint to be used for segment blocks: DEFAULT KEEP NONE See Also: Oracle Exadata Storage Server Software documentation for more information Cell flash cache 提示用于表块

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dba_segments视图

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