You should always use SECUREFILES. Also, use large uniform extents,
don't do auto-allocate. LOB segments are actually files. With LOB
segments, Oracle sort of creates a file system within a tablespace, with
each LOB column being a file. What you have is an analogy to a file
system, with a gazillion files. Theoretically, you could even use BFILE
data type, but unfortunately most file systems are not programmed so
that directories can hold hundreds of thousands of file names. And if
you try that, you fill find out that the files consume quite large
chunks of space. I've had the best experience with 32M uniform extents.
My LOB files were images. With CLOB columns you can probably get away
with smaller extents, like 8M.
On 05/13/2018 05:06 PM, Eriovaldo Andrietta wrote:
I have a table with 2 columns CLOB.
The pctfree and the pctused are equal to 10.
On this table are executed all DML operations (insert, delete and
I am looking for the best way to release the space of the LOBSEGMENT.
It must be ONLINE, I cannot drop the table and I the solution
must be implemented to be executed scheduled to run once a day.
Option 1 : shrink
alter table HISTORICO_WS_PCT10 enable row movement;
alter table HISTORICO_WS_PCT10 shrink space cascade;
ALTER TABLE HISTORICO_WS_PCT10 SHRINK SPACE;
alter table HISTORICO_WS_PCT10 DISABLE row movement;
I saw that also can be used :
ALTER TABLE HISTORICO_WS_PCT10 MODIFY LOB(xml_request) (SHRINK
ALTER TABLE HISTORICO_WS_PCT10 MODIFY LOB(xml_request) (SHRINK SPACE);
Option 2: partition
I can also to create a partitioned table , because the application uses only the data related to the current day.
So, I think it is possible to drop the partition created by RANGE (date), using sysdate - 1.
CREATE OR REPLACE PROCEDURE ERI_TST_PCTFREE10
vDateInsert := TRUNC(sysdate);
vDateDelete := vDateInsert;
DBMS_OUTPUT.PUT_LINE ('Data Insert : ' || to_char(vDateInsert,
DBMS_OUTPUT.PUT_LINE ('Data Delete : ' || to_char(vDateDelete,
FOR p in (SELECT * FROM USER_TAB_PARTITIONS
WHERE partition_name != 'HIST_DATE'
SELECT high_value INTO VAR1 FROM USER_TAB_PARTITIONS WHERE
partition_name = p.partition_name;
VAR2 := SUBSTR(VAR1, 1, 4000);
dbms_output.put_line (' Procurando : ' ||
TO_CHAR(vDateDelete, 'SYYYY-MM-DD') || ' em - ' || var2);
IF INSTR(var2, TO_CHAR(vDateDelete, 'YYYY-MM-DD')) > 0 THEN
vComando := 'ALTER TABLE HIST_WS_PCT10 DROP PARTITION ' ||
dbms_output.put_line (' vComando : ' || vComando);
EXECUTE IMMEDIATE vComando;
FOR p in (SELECT * FROM USER_INDEXES
WHERE status = 'UNUSABLE'
vComando := 'ALTER INDEX ' || p.INDEX_NAME || ' REBUILD ONLINE';
EXECUTE IMMEDIATE vComando;
In this case, I realized that I need to rebuild Indexes that were
I am thinking to use option 2.
My doubt is :
Are there another ways to release the space ?