helloppx commented on a change in pull request #1680: [CALCITE-3621] Push down
sort to DB, SQL of Sort rel contains explicit field name instead of *
URL: https://github.com/apache/calcite/pull/1680#discussion_r360756860
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File path:
core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java
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@@ -634,6 +634,13 @@ public Result visit(Sort e) {
}
Result x = visitChild(0, e.getInput());
Builder builder = x.builder(e, Clause.ORDER_BY);
+ if (builder.select.getSelectList() == null) {
Review comment:
When JdbcSort is used, a regression issue will be trigged:
JdbcTest#testSelfJoinDifferentColumns()
RelToSqlConverter visits the Sort and then produce a SQL "SELECT * from (t
JOIN t0 ...) order by ...)". However t and t0 include a field that has same
name "last_name". The outter Project will miss the correct field name.
So I think this change is needed.
Following is the regression issue info:
Before SQL:
select e1."full_name"
from "foodmart"."employee" as e1
join "foodmart"."employee" as e2 on e1."first_name" = e2."last_name"
order by e1."last_name" limit 3
REL:
JdbcToEnumerableConverter
--JdbcProject(full_name=[$1], last_name=[$3])
----JdbcSort(sort0=[$3], dir0=[ASC], fetch=[3])
------JdbcJoin(condition=[=($2, $0)], joinType=[inner])
--------JdbcProject(last_name=[$3])
----------JdbcTableScan(table=[[foodmart, employee]])
--------JdbcProject(full_name=[$1], first_name=[$2], last_name=[$3])
----------JdbcTableScan(table=[[foodmart, employee]])
After SQL:
SELECT "t2"."full_name", "t2"."last_name0" AS "last_name"
FROM (SELECT *
FROM (SELECT "last_name"
FROM "foodmart"."employee") AS "t"
INNER JOIN (SELECT "full_name", "first_name", "last_name"
FROM "foodmart"."employee") AS "t0" ON "t"."last_name" = "t0"."first_name"
ORDER BY "t0"."last_name" NULLS LAST
LIMIT 3) AS "t2"
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