Fix GH-20122: getColumnMeta() for JSON-column in MySQL #20143
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While at it, also add VECTOR.
| $stmt = $db->query('SELECT * from test'); | ||
| $meta = $stmt->getColumnMeta(0); | ||
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| // Note: JSON is an alias for LONGTEXT on MariaDB! |
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While this is true, the behaviour is not 100% the same, for example encoding JSON field as JSON does not add quotes when the value is not a string.
repro: https://dbfiddle.uk/YilhsCEk
JSON type must be preserved
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That's not possible because mariadb protocol does not make the distinction in its metadata
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@vuvova do you have an idea if the distinction of a JSON field is somehow possible?
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You can even try this in a MariaDB CLI session to see it's even stored like LONGTEXT:
MariaDB [(none)]> create database testdb;
Query OK, 1 row affected (0.000 sec)
MariaDB [(none)]> use testdb;
Database changed
MariaDB [testdb]> create table test(a JSON);
Query OK, 0 rows affected (0.032 sec)
MariaDB [testdb]> describe test;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| a | longtext | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
1 row in set (0.002 sec)
MariaDB [testdb]>
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MariaDB internally checks the JSON type like in https://github.com/MariaDB/server/blob/mariadb-12.1.1/sql/item_jsonfunc.cc#L1848.
Then I found https://github.com/MariaDB/server/blob/mariadb-12.1.1/sql/sql_type_json.h#L86 - is this really sent in the protocol?
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Okay got it, thanks for the info
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The implementation of the string change should still only be done on master. So I'll make a reminder issue to implement sending the flag + incorporating the string MariaDB sends us.
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If this is going to be changed for MySQL, I do not see any reason to not change it for MariaDB. It is more or less transport protocol detail.
I consider this as a bug as JSON type is present almost in every DB since about y2020 and the type info is important to handle the data correctly, as reproduced above.
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The JSON type was absent on both MariaDB & MySQL.
Other types may change if we send the flag and use the string the server sends back. This part is the BC break.
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In PHP it shouldn't replace the old information, it should be presented as additional information too. If it is to replace the native type then it should be behind a user facing option and disabled by default.
nielsdos
requested review from
SakiTakamachi and
kamil-tekiela
as code owners
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As far as I know, there is no JSON datatype in MySQL protocol. Has something changed recently? |
The JSON type was introduced in Mysql 5.7.8: https://dev.mysql.com/doc/refman/5.7/en/json.html but it's mainly treated as a string. |
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I cannot set up PDO_MYSQL testing environment for some reason, but I looked into this topic more and it seems I was confused before. The JSON type seems to be present in the protocol and so it can be reported as you showed. I think I confused it with ENUM. This line can also be added in |
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While at it, also add VECTOR.