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ASF GitHub Bot commented on DRILL-5419: --------------------------------------- Github user paul-rogers commented on a diff in the pull request: https://github.com/apache/drill/pull/819#discussion_r113834757 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/expr/annotations/FunctionTemplate.java --- @@ -106,15 +106,21 @@ DECIMAL_ADD_SCALE, DECIMAL_SET_SCALE, DECIMAL_ZERO_SCALE, - SC_BOOLEAN_OPERATOR + SC_BOOLEAN_OPERATOR, --- End diff -- At the very least, call it something other than "scope." The word "scope" has a very precise meaning in CS: it is the set of symbols visible to an execution context. I must admit I'm struggling to see how, say, "CONCAT" fits this. Thanks to Jinfeng for explaining that FunctionScope has evolve to mean something like "FunctionHints"... > Calculate return string length for literals & some string functions > ------------------------------------------------------------------- > > Key: DRILL-5419 > URL: https://issues.apache.org/jira/browse/DRILL-5419 > Project: Apache Drill > Issue Type: Bug > Affects Versions: 1.9.0 > Reporter: Arina Ielchiieva > Assignee: Arina Ielchiieva > Attachments: version_with_cast.JPG > > > Though Drill is schema-less and cannot determine in advance what the length > of the column should be but if query has an explicit type/length specified, > Drill should return correct column length. > For example, JDBC / ODBC Driver is ALWAYS returning 64K as the length of a > varchar or char even if casts are applied. > Changes: > *LITERALS* > String literals length is the same as actual literal length. > Example: for 'aaa' return length is 3. > *CAST* > Return length is the one indicated in cast expression. This also applies when > user has created view where each string columns was casted to varchar with > some specific length. > This length will be returned to the user without need to apply cast one more > time. Below mentioned functions can take leverage of underlying varchar > length and calculate return length. > *LOWER, UPPER, INITCAP, REVERSE, FIRST_VALUE, LAST_VALUE* > Return length is underlying column length, i.e. if column is known, the same > length will be returned. > Example: > lower(cast(col as varchar(30))) will return 30. > lower(col) will return max varchar length, since we don't know actual column > length. > *LAG, LEAD* > Return length is underlying column length but column type will be nullable. > *LPAD, RPAD* > Pads the string to the length specified. Return length is this specified > length. > *CONCAT, CONCAT OPERATOR (||)* > Return length is sum of underlying columns length. If length is greater then > varchar max length, varchar max length is returned. > *SUBSTR, SUBSTRING, LEFT, RIGHT* > Calculates return length according to each function substring rules, for > example, taking into account how many char should be substracted. > *IF EXPRESSIONS (CASE STATEMENT, COALESCE), UNION OPERATOR* > When combining string columns with different length, return length is max > from source columns. -- This message was sent by Atlassian JIRA (v6.3.15#6346)