Can the station registry accept UTF-8 in a station description? about website HOT 5 OPEN

i just tried an alter on the description field to make it utf8. need to do more research to see what cause this behavior to start, but i suspect an upgrade to mysql would have done it.

so far i do not see more messages like this in error.log, but we'll see...

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here is the table before and after, and the alter command.

alter table `stations` change `description` `description` varchar(255) character set utf8mb4 default NULL;

mysql> show create table stations \G
*************************** 1. row ***************************
       Table: stations
Create Table: CREATE TABLE `stations` (
  `station_url` varchar(255) NOT NULL,
  `description` varchar(255) DEFAULT NULL,
  `latitude` float DEFAULT NULL,
  `longitude` float DEFAULT NULL,
  `station_type` varchar(64) DEFAULT NULL,
  `station_model` varchar(128) DEFAULT NULL,
  `weewx_info` varchar(64) DEFAULT NULL,
  `python_info` varchar(64) DEFAULT NULL,
  `platform_info` varchar(128) DEFAULT NULL,
  `last_addr` varchar(16) DEFAULT NULL,
  `last_seen` int DEFAULT NULL,
  UNIQUE KEY `index_url` (`station_url`),
  KEY `index_addr` (`last_addr`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1

mysql> show create table stations \G
*************************** 1. row ***************************
       Table: stations
Create Table: CREATE TABLE `stations` (
  `station_url` varchar(255) NOT NULL,
  `description` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL,
  `latitude` float DEFAULT NULL,
  `longitude` float DEFAULT NULL,
  `station_type` varchar(64) DEFAULT NULL,
  `station_model` varchar(128) DEFAULT NULL,
  `weewx_info` varchar(64) DEFAULT NULL,
  `python_info` varchar(64) DEFAULT NULL,
  `platform_info` varchar(128) DEFAULT NULL,
  `last_addr` varchar(16) DEFAULT NULL,
  `last_seen` int DEFAULT NULL,
  UNIQUE KEY `index_url` (`station_url`),
  KEY `index_addr` (`last_addr`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1

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actually, that latin1 is kind of obvious. when did that appear? pretty sure it was not part of the original table creation. so perhaps a mysql upgrade added that to make it explicit, thus breaking any inserts that contain utf8?

sorry, but character encodings are one of my many weaknesses

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the latin1 is there apparently because i did not specify a characterset when i originally created the tables eons ago, so it defaulted to latin1. apparently mysql 8 (running on weewx.com as of this writing nov 2022) defaults to utf8 (not sure whether that is 3-byte or 4-byte).

i'm not crazy about altering everything in the database. description should obviously accept non-latin characters, but should any other fields?

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Interesting.

Internally, I'm sure MySQL stores it as a byte string. However, it appears that the database engine is also enforcing character type safety. That is, if you declare the field as Latin-1, then try to store something that uses non-Latin-1 characters, it will declare an error.

When it comes time to print the field out, the MySQL client will use the encoding to figure out what code point to use.

I believe that UTF-8 domain names are valid these days, although most DNS servers don't support them. To future proof things, I would use utf-8 encoding for station_url as well.

The other fields should be fine.

It's an ancient article, but I recommend Joel Spolsky's The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets. It set me straight now 20 years ago!

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