Shulou(Shulou.com)06/01 Report--

The known types of SQL statements that MyCat does not support are as follows:

SELECT:

Cross query across fragments (entity library)

A federated query across nodes (such as a federated query between the tables of the user library and the table of the platform library)

INSERT:

The inserted field does not contain sharded fields (for example, insert tbl_user_base_info table, no user_ id column is provided)

The inserted shard field cannot find the corresponding shard.

Copy insert Insert into … Select...

Multi-line insertion of insert into tab_a (C1 ~ c2) values (v1 ~ ~ 2), (v11 ~ ~ v21).

UPDATE:

Updated columns contain sharded columns

Multi-table update update a, b set a.nationalizationChina, b.pwdflowers 123456 'where a.id=b.id

Complex update update a, b set a.nationalizedChina`where a.idroomb.id; but the subquery method update a set a.nationalization China`where id in (select id from b) is supported.

DELETE:

Complex deletion of delete a from a join b on a.idaccounb.id; subquery method delete from a where a.id in (select id from b) is supported, but the table cannot be aliased

Other:

Call procedure () MyCat does not support stored procedure definitions, so calls to stored procedures are not allowed, but stored procedures on each shard can be called through annotations

Selectfunc (); does not support calling custom functions directly, but supports select id. Func () from employee only needs this function to exist on all shards where employee resides. MySql comes with functions that can be used at will.

Note:

The Order by field must appear in the select (MyCat first takes out the results and then sorts them)

Group by must use standard syntax select count (1), type from tab_a group by type

Some of the built-in functions of MyCat, such as sum,min,max, can be used correctly, but the avg executed in multiple parts has bug, and the result is wrong.

Use subqueries with caution. If the outer query has no sharding query condition, it will be executed on all shards (the inner and outer tables of the subquery are as special)

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