store: Added core support for “metrics” objects.

[sysdb.git] / src / include / core / data.h

diff --git a/src/include/core/data.h b/src/include/core/data.h
index 2e9b90bcfd55af660d3cb576b1c5e3e21427730e..6e4d3174e4c45bb42397345a58719c2b888ac27f 100644 (file)
--- a/src/include/core/data.h
+++ b/src/include/core/data.h
@@ -143,9 +143,15 @@ enum {
 
 /*
  * sdb_data_expr_eval:
- * Evaluate a simple arithmetic expression on two data points. The data-type
- * of d1 and d2 have to be the same. String and binary data only support
- * concatenation and all other data types only support the other operators.
+ * Evaluate a simple arithmetic expression on two data points. String and
+ * binary data only support concatenation and all other data types only
+ * support the other operators. The result may be allocated dynamically and
+ * has to be freed by the caller (using sdb_data_free_datum).
+ *
+ * The data-types of d1 and d2 have to be the same, except for the following
+ * cases:
+ *  - <integer> or <decimal> <mul> <datetime>
+ *  - <datetime> <mul> or <div> or <mod> <integer> or <decimal>
  *
  * Returns:
  *  - 0 on success