How to list subpartitions and their LOB segment sizes

The query below will list the lob segment names, the lob subpartition names, the table subpartition names and sizing information for any subpartitioned tables using LOB columns:

SELECT  ts.table_owner "table owner",
        ts.table_name "table name",
        s.SEGMENT_NAME "segment name",
        s.SEGMENT_TYPE "segment type",
        s.SEGMENT_SUBTYPE "lob type",
        s.PARTITION_NAME "lob subpart name",
        lsp.column_name "lob name",
        lsp.compression "lob compression",
        lsp.subpartition_name "table subpartition name",
        ts.num_rows "num rows",
        lsp.tablespace_name "tablespace",
        ROUND(sum(s.bytes)/1024/1024/1024) "size GB"
FROM dba_segments s JOIN dba_lob_subpartitions lsp
ON (s.partition_name = lsp.lob_subpartition_name)  
   JOIN DBA_TAB_SUBPARTITIONS ts
        ON (TS.SUBPARTITION_NAME = lsp.SUBPARTITION_NAME) 
WHERE lsp.table_name='DOCUMENTS'
AND   ts.table_name='DOCUMENTS'
-- To limit the output to a specific tablespace, uncomment line below
-- AND   s.tablespace_name='DATA1'
-- To limit output to specific table subpartitions only, uncomment the following row
--AND   lsp.subpartition_name like 'SYS_SUBP186786%'
AND s.segment_name IN ( SELECT lpt.lob_name 
                        FROM dba_lob_partitions lpt 
                        WHERE lpt.table_name IN ( 'DOCUMENTS' ) )

GROUP BY ts.table_owner,ts.table_name,s.SEGMENT_NAME,s.SEGMENT_TYPE,s.SEGMENT_SUBTYPE,s.PARTITION_NAME,lsp.COMPRESSION,lsp.subpartition_name, lsp.column_name,ts.num_rows,lsp.tablespace_name
/*
To limit output to lob subpartitions with a specific size, 
uncomment the restriction above and change the operator to suit your needs ( <, >, =) 
or use BETWEEN x AND y
*/
-- HAVING ROUND(sum(s.bytes)/1024/1024/1024) between 1 and 10
ORDER BY lsp.subpartition_name DESC;

Example output:

TABLE_NAME	segment name	segment type	lob type	lob subpart name	lob compression	table subpartition name	num rows	tablespace	size GB
MYTABLE	MYTABLE_LOB7	LOB SUBPARTITION	SECUREFILE	KLM_DOCS_2018_01	MEDIUM	KLM_SP_2018_01	164497	DOCS2018	235
MYTABLE	MYTABLE_LOB7	LOB SUBPARTITION	SECUREFILE	VISA_DOCS_2018_01	MEDIUM	VISA_SP_2018_01	72405	DOCS2018	76
MYTABLE	MYTABLE_LOB7	LOB SUBPARTITION	SECUREFILE	KLM_DOCS_2017_10	MEDIUM	KLM_SP_2017_10	16256	DOCS2017	19
MYTABLE	MYTABLE_SMALL_LOB7	LOB SUBPARTITION	SECUREFILE	KLM_DOCS_SMALL_2018_01	MEDIUM	KLM_SP_2018_01	164497	DOCS2018	18
MYTABLE	MYTABLE_SMALL_LOB7	LOB SUBPARTITION	SECUREFILE	VISA_DOCS_SMALL_2018_01	MEDIUM	VISA_SP_2018_01	72405	DOCS2018	8