I have a table named EMP with a BLOB data type for storing the photos of each employee. I want a query to find what the size is of that BLOB object.
In order to find out the size of LOBs in your database, you'll want to use the DBMS_LOB supplied PL/SQL package, specifically the GETLENGTH procedure. The Oracle docs give the following example on determine the LOB size:
CREATE OR REPLACE PROCEDURE Example_11a IS lobd BLOB; length INTEGER; BEGIN -- get the LOB locator SELECT b_lob INTO lobd FROM lob_table WHERE key_value = 42; length := dbms_lob.getlength(lobd); IF length IS NULL THEN dbms_output.put_line('LOB is null.'); ELSE dbms_output.put_line('The length is ' || length); END IF; END;
Basically, you get the LOB locator from your table. This locator points to the LOB. Using this locator, you call the DBMS_LOB.GETLENGTH procedure to determine the LOB size.
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