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 * when sort
is not top rel
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()
Following is the regression issue info:
Input SQL: A
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
Best 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]])
Output SQL: B
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"
After fix, output SQL: C
SELECT "t2"."full_name", "t2"."last_name0" AS "last_name"
FROM (SELECT "t"."last_name", "t0"."full_name", "t0"."first_name",
"t0"."last_name" AS "last_name0"
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"
SQL B is wrong, since "t2" is a subquery but it's select list is ambiguous.
Database complains "last_name0" cannot be found in schema.
that is, the SQL of RelToSqlConverter#visit(Sort e) generated should has
explicit select list when the Sort is not outter rel.
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