continue to treat MySQL fields as binary and store pure UTF-8 Unicode in them, although MySQL may have them listed as Latin-1 depending on your server's defaults. Surely this is a bug? If MW wants binary fields, then surely it should explicitly create them as binary, instead of leaving it up to some random server default? Ian -----Original Message----- From: Brion Vibber [mailto:brion@wikimedia.org] Sent: Friday, May 04, 2007 08:18 AM Pacific Standard Time To: MediaWiki announcements and site admin list Subject: Re: [Mediawiki-l] Sudden problem with some greek andcyrillic letters -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Sylvain Machefert wrote: Yes -- the page text is in a binary BLOB field, which will not undergo the bogus lossy conversion. The summarize, the problem is roughly: * MediaWiki assumes that MySQL will preserve data that is put into it * MySQL sometimes corrupts the data in a little more detail: * Due to the limitations of MySQL's Unicode support, but default we continue to treat MySQL fields as binary and store pure UTF-8 Unicode in them, although MySQL may have them listed as Latin-1 depending on your server's defaults. * The mysqldump backup program by default in 4.1 and later applies a conversion of non-binary fields to UTF-8, with a marker to have them appropriately converted back when read in. * This conversion is lossy -- it treats Latin-1 as the Windows-1252 code page, which is an extension of ISO 8859-1 with additional characters in the 128-159 range which in ISO 8859 and Unicode is supposed to contain non-printing control characters. Four of the code points in this range are not assigned in Windows-1252, and so cannot be converted to UTF-8 Unicode -- these characters are silently corrupted into "?" characters during the conversion if they appear. * The UTF-8 encoding of Unicode uses the byte values which correspond to those four non-convertible characters. * As a result, UTF-8 text in a Latin-1 field may be corrupted, as some characters are destroyed in the conversion back and forth. Use the --default-charset=latin1 option on mysqldump when creating your database dumps to avoid this lossy conversion. (And/or find another way to dump/copy databases or another equivalent option to avoid the unnecessary conversion.) Since it appears that your hosting provider did this for you, you may need to ask them to redo it. Alternatively, you may be able to rig up a statistical fix based on which characters are being corrupted, though I'm not sure how easy that would be. - -- brion vibber (brion @ wikimedia.org) _______________________________________________ MediaWiki-l mailing list MediaWiki-l(a)lists.wikimedia.org http://lists.wikimedia.org/mailman/listinfo/mediawiki-l