Add a list of unsupported functions #672
Description
See pingcap/tidb#158
For users coming from a MySQL background, it is very useful to include a list of unsupported functions to each function overview page.
- Control Flow Functions @morgo reference/sql/functions-and-operators: update list #1262
- String Functions @morgo reference/sql/functions-and-operators: update list #1262
- Numeric Functions and Operators @morgo reference/sql/functions-and-operators: update list #1262
- Date and Time Functions @morgo reference/sql/functions-and-operators: update list #1262
- Bit Functions and Operators @morgo reference/sql/functions-and-operators: update list #1262
- Cast Fuctions and Operators @morgo reference/sql/functions-and-operators: update list #1262
- Encryption and Compression Functions @morgo reference/sql/functions-and-operators: update list #1262
- Information Functions @morgo reference/sql/functions-and-operators: update list #1262
- JSON Functions @morgo #656
- Aggregate Functions @morgo #657
- Miscellaneous Functions @morgo reference/sql/functions-and-operators: update list #1262
Comparing to the MySQL manual, they also have these sections:
- XML Functions (documented in mysql compatibility as not supported)
- Fulltext Search functions (documented as unsupported)
- Spatial Analysis functions (documented as unsupported)
- Functions used with GTID (not relevant)
- MySQL Enterprise Encryption functions (not required)
Suggested Approach:
Take a look at pingcap/tidb#158
There may be cases where a function was added but not checked off.
It is easiest to complete this task by first changing the list of functions to be alphabetically sorted (as they are in MySQL documentation). Then you can compare the page to MySQL docs and document what is missing.
For example, on the string functions page you can see that TiDB is missing: LOAD_FILE, MATCH, SOUNDEX / SOUNDS LIKE, WEIGHT_STRING.
In the event that TiDB supports all functions for that category, I suggest we still add the section since users may train themselves to look for it. It can say something simple like "TiDB supports all XYZ functions".