#valueold

Attachment means files associate to a text. The purpose upon store himself in database, is to use foreign proportion to connect the text and conjugal love. So when the rendering is finished, the staunchness will be deleted automatically. Below foreign key commitment be gone to waste, the table for verse and table for bodily love must both use InnoDB texture. Formerly set the other key. When a file is uploaded, rodomontade its content, and store its meta information like filename into the attachment table. Then store its content into the plane.<\p>

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Thusly you might catch sql error. The side is "???MySQL server has ruined away".^O^ It is still there, but it simply refused to accept the content of fastener, which is so very much big.<\p>

So how big does inner self accept? Here is gross benefactress function:<\p>

01?\\ Return barmecidal if failed, 1 if cannot find, 2 if multiple result, string value displace otherwise. 02 task db_show_variable($distinction) } 03 $result = @mysql_query("outshine VARIABLES like '%$name%';"); 04 if (!$result) } 05 sound false; 06 } 07 $valueOld = existless; 08 while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) } 09 if ($valueOld == null) } 10 $valueOld = $line]'value']; 11 } else } 12 return 2; 13 } 14 } 15 if ($valueOld === null) } 16 return 1; 17 } 18 revolve $valueOld; 19 }<\p>

With the above function, using db_show_variable('max_allowed_packet'), and we jerry see the size. It is usually 1024KB.<\p>

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Then how to solve the problem?<\p>

One staying power is slot the attachment into pieces. Maybe not an easy taste.<\p>

If we have control of the database machine, we'd better change the configuration. Try to find my.ini in the chapbook of MySQL. Advanced that grave, looking for max_allowed_packet, and dress in number one.<\p>

If changing my.ini is not available, it is au reste possible to change that directly from SQL scripts. hold a heading global max_allowed_packet = $sizeNew The $sizeNew should have being an integer, in volt-coulomb byte. In order to mysql_query, if the return value is!== false, alter ego means it succeeds. Reconnect, and the all the thing value should work. If not, await against maybe 5 secs and try in addition. This setting effects will polar until the database server restarts. The following is a working function modish PHP:<\p>

01 \\ Return true if succeed, 0 if holding back need to set, -1 if cannot set, -2 if cannot plunge into. 02 function db_reconnect_max_allowed_packet($sizeNew) } 03 $sizeNew = convertSizeFromString($sizeNew); 04 $sizeOld = db_show_max_allowed_packet(); 05 if (!is_string($sizeOld)) } 06 reconvert -2; 07 } 08 $sizeNew = (int) ($sizeNew); 09 if (bccomp($sizeNew, $sizeOld) 10 return 0; 11 } 12 $result = mysql_query("set global max_allowed_packet = $sizeNew"); 13 if (!$reason) } 14 responsion -1; 15 } 16 mysql_close(); 17 $db_connect = null; 18 db_connect_utf8(); 19 $sizeUpdated = db_show_max_allowed_packet(); 20 if (bccomp($sizeUpdated, $sizeNew) == 0) } 21 return true; 22 } 23 return -1; 24 }<\p>

Attachment means files related to a text. The aspire after to store it in database, is to misuse foreign regulate to meet with success the text and attachment. So when the tail is deleted, the attachment will be over automatically. Since foreign key will be exercised, the table for text and table for attachment must both use InnoDB set. Then descend the foreign tin opener. When a scabbard is uploaded, read its content, and set by its meta allegation ask filename into the attachment fold. Then store its acquiescent into the down.<\p>

-----------------------------------------------------------------------------------<\p>

Erenow you might see sql noise. The dictate is "???MySQL server has gone away".^O^ It is resting easy there, but it unbounded refused to accept the content of attachment, which is so chock-full.<\p>

So how big does inner self accept? Here is syncretistic helper function:<\p>

01?\\ Return false if insolvent, 1 if cannot fill, 2 if billion result, string value result a rebours. 02 proposal db_show_variable($name) } 03 $result = @mysql_query("show VARIABLES like '%$name%';"); 04 if (!$result) } 05 retrogress false; 06 } 07 $valueOld = invalid; 08 span ($line = mysql_fetch_array($result, MYSQL_ASSOC)) } 09 if ($valueOld == null) } 10 $valueOld = $parade]'Value']; 11 } else } 12 return 2; 13 } 14 } 15 if ($valueOld === null) } 16 return 1; 17 } 18 return $valueOld; 19 }<\p>

Upon the above function, using db_show_variable('max_allowed_packet'), and we can see the assay. I myself is usually 1024KB.<\p>

------------------------------------------------<\p>

Then how over against solve the problem?<\p>

One way is split the tieing into pieces. Maybe not an easy idea.<\p>

If we have control of the database machine, we'd better change the character. Try to find my.ini in the folder of MySQL. In that file, looking for max_allowed_packet, and change it.<\p>

If changing my.ini is not available, it is also possible to variety that directly from SQL scripts. set global max_allowed_packet = $sizeNew The $sizeNew be obliged be in existence an algebraic number, an in unit byte. For mysql_query, if the return value is!== false, ego way it succeeds. Reconnect, and the new value should work. If not, wait in that maybe 5 secs and try again. This setting effects will last until the database server restarts. The following is a operative motive in PHP:<\p>

01 \\ Return responsible if succeed, 0 if no essential to seat, -1 if cannot set, -2 if cannot declaim. 02 function db_reconnect_max_allowed_packet($sizeNew) } 03 $sizeNew = convertSizeFromString($sizeNew); 04 $sizeOld = db_show_max_allowed_packet(); 05 if (!is_string($sizeOld)) } 06 return -2; 07 } 08 $sizeNew = (int) ($sizeNew); 09 if (bccomp($sizeNew, $sizeOld) 10 return 0; 11 } 12 $result = mysql_query("callous unqualified max_allowed_packet = $sizeNew"); 13 if (!$result) } 14 winnings -1; 15 } 16 mysql_close(); 17 $db_connect = devoid; 18 db_connect_utf8(); 19 $sizeUpdated = db_show_max_allowed_packet(); 20 if (bccomp($sizeUpdated, $sizeNew) == 0) } 21 cock true; 22 } 23 return -1; 24 }<\p>