Excessive disk space consumption on BLOB concatenation
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Key: CORE-3948
URL: http://tracker.firebirdsql.org/browse/CORE-3948
Project: Firebird Core
Issue Type: Bug
Components: Engine
Affects Versions: 2.5.1
Environment: Windows 7 Professional 64bit
Reporter: Jörg Fröber
When a blob is being concatenated mulitple times, the disk space for the
database file grows massively. The only way to get the file size back to normal
is a backup and restore of the database.
The issue can be reproduced as described below:
- Create an empty database
- Create the following procedure:
SET TERM ^ ;
CREATE OR ALTER PROCEDURE P_TEST (
TEST VARCHAR(200),
ITERATIONS INTEGER)
RETURNS (
BLOBTEXT BLOB SUB_TYPE 0 SEGMENT SIZE 80)
AS
DECLARE COUNTER INTEGER;
BEGIN
COUNTER = 0;
BLOBTEXT = '';
WHILE (COUNTER < ITERATIONS)
DO
BEGIN
BLOBTEXT = BLOBTEXT || ' ' || TEST;
COUNTER = COUNTER + 1;
END
SUSPEND;
END^
SET TERM ; ^
GRANT EXECUTE ON PROCEDURE P_TEST TO "PUBLIC";
GRANT EXECUTE ON PROCEDURE P_TEST TO SYSDBA;
- run the procedure:
SELECT BLOBTEXT FROM P_TEST('This is a test sentence, which is going to be
concatenated.', 4000);
After the procedure has been executed, the disk space used by the database file
increases to over 1 GB. It makes no difference, if the transaction is committed
or not.
When you run the procedure another time using the SQL-command EXECUTE PROCEDURE
P_TEST('This is a test sentence, which is going to be concatenated.', 4000);
the file size increases again.
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