wuchong commented on a change in pull request #9994: [FLINK-14322][table-api]
Add watermark information in TableSchema
URL: https://github.com/apache/flink/pull/9994#discussion_r341510296
##########
File path:
flink-table/flink-table-common/src/main/java/org/apache/flink/table/api/TableSchema.java
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@@ -343,13 +404,36 @@ public Builder field(String name, TypeInformation<?>
typeInfo) {
return field(name, fromLegacyInfoToDataType(typeInfo));
}
+ /**
+ * Specifies the previously defined field as an event-time
attribute and specifies the watermark strategy.
+ *
+ * @param rowtimeAttribute the field name as a rowtime
attribute, can be a nested field using dot separator.
+ * @param watermarkExpressionString the string representation
of watermark generation expression,
+ * e.g. "ts - INTERVAL '5'
SECOND". The string is a qualified SQL expression
+ * string (UDFs are expanded)
but will not be validated by {@link TableSchema}.
+ * @param watermarkExprOutputType the data type of the
computation result of watermark generation expression.
+ * Whether the data type equals
to the output type of expression will also
+ * not be validated by {@link
TableSchema}.
+ */
+ public Builder watermark(String rowtimeAttribute, String
watermarkExpressionString, DataType watermarkExprOutputType) {
+ Preconditions.checkNotNull(rowtimeAttribute);
Review comment:
We don't run out of characters. A better field name describes everything. If
we use `watermarkExpr`, some users may guess it is an `Expression` but is a
`String`.
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