Hi We want to introduce a new wildcard **, to improve the DDL and DML of IoTDB-SQL.
As we all know, a time series is represented by a full path from the root node to the measurement node in the metadata tree. The existing wildcard *, when used in the path, represents one level of the metadata tree and one or more levels when used at the tail of the path. After introducing wildcard **, we want wildcard ** to represent one or more levels of the MTree wherever used in the path, and wildcard * to only represent one level even if used at the tail of the path. Besides, we want to define the path given by a sql statement as a pattern of the target paths rather than a prefix. Some SQL statements' meaning may be different from the old versions. Here are some detailed examples and explanations of the wildcard usage. Please refer to https://shimo.im/docs/8c3Qrp88ph39QHdv/ Best ----------------------------- Yukun Zhou School of Software, Tsinghua University 周钰坤 清华大学 软件学院
