GS_SEG_EXTENTS

GS_SEG_EXTENTS displays extent information about all tablespaces. This view displays all extents of user segments, including segment heads, fork heads, and level-1 pages in file 1 and data extents in files 2 to 5. Only an administrator can query the information.

**Table 1** GS_SEG_EXTENTS columns
Name	Type	Description
node_name	text	Node name.
tablespace_name	name	Tablespace to which a segment object belongs.
bucketnode	integer	0 to 1023 indicate the bucket nodes of a hash bucket table. 1024 indicates the bucket node of a segment-page ordinary table. 1025 indicates the bucket node of a segment-page global temporary table. 1026 indicates the bucket node of a segment-page unlogged table. 1027 indicates the bucket node of a segment-page local temporary table. 2048 to 6143 indicate the bucket nodes of a range bucket table.
head_block_id	bigint	Page number of the segment header.
extent_id	integer	Logical extent number.
file_id	integer	ID of the data file where the extent is located. Value range: an int4 value in the range [1,5].
forknum	integer	Fork type of a segment object. Value range: 0: main fork. 1: FSM fork. 2: VM fork.
block_id	bigint	Start page number in the data file where the extent is located.
blocks	integer	Extent size. The value can be 1, 8, 128, 1024, or 4096.
usage_type	text	Usage type of the extension. Value range: segment head: segment header. fork head: fork header. level1 page: level-1 page. data extent: data extents.