Hi Alexey, More input: == Circular dependencies are allowed == This query will cause an assert in the optimizer, for obvious reasons: select * from json_table(JS3.size, '$' columns (size INT PATH '$.size')) as JS1, json_table(JS1.size, '$' columns (size INT PATH '$.size')) as JS2, json_table(JS1.size, '$' columns (size INT PATH '$.size')) as JS3 where 1; == Character set inference is wrong == create table t20 (json varchar(100) character set utf8); insert into t20 values ('{"value":"АБВ"}'); create table tj20 as select T.value from t20, json_table(t20.json, '$' columns (value varchar(32) PATH '$.value')) T; mysql> show create table tj20\G *************************** 1. row *************************** Table: tj20 Create Table: CREATE TABLE `tj20` ( `value` varchar(32) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1 The source document uses UTF-8 but the values from it are in latin1? == Comments and code cleanup == There are a lot of comments missing, some duplicate code, and code using out-of-date ways of doing things. Please find attached a patch with obvious fixes for most of it. == Explain == Let's follow MySQL here: let the tabular EXPLAIN show "Table function: json_table" in the Extra column, let EXPLAIN FORMAT=JSON show "table_function": "json_table" in the "table" element. BR Sergei -- Sergei Petrunia, Software Developer MariaDB Corporation | Skype: sergefp | Blog: http://s.petrunia.net/blog