JSON Functions

JSON function differences:

1. For JSON functions and other character input parameter functions, if the input contains escape characters, you need to set the GUC parameter set standard_conforming_strings to off, which is different from MySQL by default. In this case, escape characters are compatible with MySQL. However, a warning alarm is generated for non-standard character input. Escape characters \t and \u, and escape digits are different from those in MySQL. If the GUC parameter is not set, the JSON_UNQUOTE() function is still compatible with MySQL and no alarm is reported.
2. When processing an ultra-long number (the number contains more than 64 characters), the JSON function of GaussDB parses the number as a DOUBLE and uses scientific notation for counting. The input parameters of the non-JSON type are the same as those of MySQL. However, when input parameters of the JSON type are used, the JSON type is not completely compatible with MySQL. As a result, differences occur in this scenario. MySQL displays complete numbers. (When the number length exceeds 82, MySQL displays an incorrect result.) GaussDB still parses an ultra-long number into a double-precision value. Long numbers are stored using floating-point numbers. During calculation, precision loss occurs in both GaussDB and MySQL. Therefore, you are advised to use character strings to store long numbers.

   gaussdb=# select json_insert('[1, 4, 99999999999999999999999999999999999999999999999999999999999999999999999999]','$[6]',json_insert('[1,4]','$[5]',99999999999999999999999999999999999999999999999999999999999999999999999999));
            json_insert          
   ------------------------------
    [1, 4, 1e+74, [1, 4, 1e+74]]
   (1 row)