From 6f14f039aad8fb6f0b8210071df56009a7677e41 Mon Sep 17 00:00:00 2001
From: lbrdnk <lbrdnk@users.noreply.github.com>
Date: Wed, 17 Apr 2024 20:53:42 +0200
Subject: [PATCH] Cancel statement on completion of `execute-reducible-query`
(#41470)
* Cancel statement on completion of execute-reducible-query
* Address review remarks
---
src/metabase/driver/sql_jdbc/execute.clj | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/src/metabase/driver/sql_jdbc/execute.clj b/src/metabase/driver/sql_jdbc/execute.clj
index 10d02abe8e6..f96f0152c3e 100644
--- a/src/metabase/driver/sql_jdbc/execute.clj
+++ b/src/metabase/driver/sql_jdbc/execute.clj
@@ -32,7 +32,8 @@
[metabase.util.malli :as mu]
[potemkin :as p])
(:import
- (java.sql Connection JDBCType PreparedStatement ResultSet ResultSetMetaData Statement Types)
+ (java.sql Connection JDBCType PreparedStatement ResultSet ResultSetMetaData SQLFeatureNotSupportedException
+ Statement Types)
(java.time Instant LocalDate LocalDateTime LocalTime OffsetDateTime OffsetTime ZonedDateTime)
(javax.sql DataSource)))
@@ -713,7 +714,18 @@
e))))]
(let [rsmeta (.getMetaData rs)
results-metadata {:cols (column-metadata driver rsmeta)}]
- (respond results-metadata (reducible-rows driver rs rsmeta qp.pipeline/*canceled-chan*))))))))
+ (try (respond results-metadata (reducible-rows driver rs rsmeta qp.pipeline/*canceled-chan*))
+ ;; Following cancels the statment on the dbms side.
+ ;; It avoids blocking `.close` call, in case we reduced the results subset eg. by means of
+ ;; [[metabase.query-processor.middleware.limit/limit-xform]] middleware, while statment is still
+ ;; in progress. This problem was encountered on Redshift. For details see the issue #39018.
+ ;; It also handles situation where query is canceled through [[qp.pipeline/*canceled-chan*]] (#41448).
+ (finally (try (.cancel stmt)
+ (catch SQLFeatureNotSupportedException _
+ (log/warnf "Statemet's `.cancel` method is not supported by the `%s` driver."
+ (name driver)))
+ (catch Throwable _
+ (log/warn "Statement cancelation failed.")))))))))))
(defn reducible-query
"Returns a reducible collection of rows as maps from `db` and a given SQL query. This is similar to [[jdbc/reducible-query]] but reuses the
--
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