LOG domain specific language (DSL) of Log Service provides expression functions that return specific values to help you process log data.

The following table lists the expression functions.
Type Function Description
Event check functions Functions such as v, e_has, e_not_has, e_search, e_match, e_match_any, and e_match_all Returns the values of fields, or checks whether a field or the value of a field meets specified conditions.
Operator functions Some op_* functions Compares values, performs condition-based or containment judgment, or performs general multi-value calculation.
Conversion functions ct_* functions Converts data types among numeric strings, strings, and Boolean values, or converts numbers between different numeral systems.
Arithmetic functions Functions such as some op_* functions and math_* functions Performs mathematical calculation or multi-value calculation.
String functions str_* functions Processes strings.
Date and time functions dt_* functions Converts time data among UNIX timestamps, datetime objects, and date and time strings, changes the time zone, modifies date and time, or returns the difference between two time values.
Regular expression functions reg_* functions Extracts, returns, replaces, or splits values based on regular expressions.
Grok function grok function Extracts specific values based on regular expressions.
Structured data functions json_*, xml_*, and pb_* functions Extracts or parses fields.
Encoding and decoding functions url_*, html_*, md5_*, sha1_*, and base64_* functions Encodes or decodes data.
List functions lst_* functions Constructs, returns, or modifies a list.
Dictionary functions dct_* functions Constructs, returns, or modifies a dictionary.
Table functions tab_* functions Constructs a table from a text file or constructs a dictionary from a table.
Resource functions res_* functions Returns advanced parameters of the current data processing task, or obtains data from resources such as Relational Database Service (RDS) databases and Logstores.