COMPRESS
Sintassi
COMPRESS(stringa_da_comprimere)
Spiegazione
Comprime una stringa e restituisce il risultato come stringa binaria. Questa funzione richiede che MariaDB sia stata compilata con una libreria di compressione, come zlib. Altrimenti il valore restituito sarà sempre NULL. La stringa compressa potrà essere decompressa con UNCOMPRESS().
Esempi
MariaDB [(none)]> SELECT LENGTH(COMPRESS(REPEAT('a',1000)));
+------------------------------------+
| LENGTH(COMPRESS(REPEAT('a',1000))) |
+------------------------------------+
| 21 |
+------------------------------------+
1 row in set (0.00 sec)
MariaDB [(none)]> SELECT LENGTH(COMPRESS(''));
+----------------------+
| LENGTH(COMPRESS('')) |
+----------------------+
| 0 |
+----------------------+
1 row in set (0.00 sec)
MariaDB [(none)]> SELECT LENGTH(COMPRESS('a'));
+-----------------------+
| LENGTH(COMPRESS('a')) |
+-----------------------+
| 13 |
+-----------------------+
1 row in set (0.00 sec)
MariaDB [(none)]> SELECT LENGTH(COMPRESS(REPEAT('a',16)));
+----------------------------------+
| LENGTH(COMPRESS(REPEAT('a',16))) |
+----------------------------------+
| 15 |
+----------------------------------+
1 row in set (0.00 sec)
MariaDB [(none)]>
Commenti
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Compress don't work for me, I obtain the error: Incorrect string value: '\x9C+\xC8,(\xC8...' for column
the script is: update notifica set dom = compress('pippo') where id_notifica = 319798;
where column "dom" is mediumtext and table is UTF8, I tried also with utf8mb4 but nothing, compress don't work. thanks
Add information, the SELECT compress(dom) FROM notifica; works fine. thanks