Hi,
I liked this idea and after reviewing code I noticed some moments and
I'd rather ask you some questions.
Firstly, I suggest some editing in the comment of commit. I think, it is
turned out the more laconic and the same clear. I wrote it below since I
can't think of any other way to add it.
```
Currently, we have to wait for finishing of the query execution to check
its plan.
This is not so convenient in investigation long-running queries on
production
environments where we cannot use debuggers.
To improve this situation there is proposed the patch containing the
pg_log_query_plan()
function which request to log plan of the specified backend process.
By default, only superusers are allowed to request log of the plan
otherwise
allowing any users to issue this request could create cause lots of log
messages
and it can lead to denial of service.
At the next requesting CHECK_FOR_INTERRUPTS(), the target backend logs
its plan at
LOG_SERVER_ONLY level and therefore this plan will appear in the server
log only,
not to be sent to the client.
```
Secondly, I have question about deleting USE_ASSERT_CHECKING in lock.h?
It supposed to have been checked in another placed of the code by
matching values. I am worry about skipping errors due to untesting with
assert option in the places where it (GetLockMethodLocalHash)
participates and we won't able to get core file in segfault cases. I
might not understand something, then can you please explain to me?
Thirdly, I have incomprehension of the point why save_ActiveQueryDesc is
declared in the pquery.h? I am seemed to save_ActiveQueryDesc to be used
in an once time in the ExecutorRun function and its declaration
superfluous. I added it in the attached patch.
Fourthly, it seems to me there are not enough explanatory comments in
the code. I also added them in the attached patch.
Lastly, I have incomprehension about handling signals since have been
unused it before. Could another signal disabled calling this signal to
log query plan? I noticed this signal to be checked the latest in
procsignal_sigusr1_handler function.
Regards,
--
Alena Rybakina
Postgres Professional
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index a82ac87457e..65b692b0ddf 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -306,6 +306,12 @@ ExecutorRun(QueryDesc *queryDesc,
{
QueryDesc *save_ActiveQueryDesc;
+ /*
+ * Save value of ActiveQueryDesc before having called
+ * ExecutorRun_hook function due to having reset by
+ * AbortSubTransaction.
+ */
+
save_ActiveQueryDesc = ActiveQueryDesc;
ActiveQueryDesc = queryDesc;
@@ -314,6 +320,7 @@ ExecutorRun(QueryDesc *queryDesc,
else
standard_ExecutorRun(queryDesc, direction, count, execute_once);
+ /* We set the actual value of ActiveQueryDesc */
ActiveQueryDesc = save_ActiveQueryDesc;
}
diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index fc9f9f8e3f0..8e7ce3c976f 100644
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -126,6 +126,7 @@ extern void ExplainOpenGroup(const char *objtype, const char *labelname,
extern void ExplainCloseGroup(const char *objtype, const char *labelname,
bool labeled, ExplainState *es);
+/* Function to handle the signal to output the query plan. */
extern void HandleLogQueryPlanInterrupt(void);
extern void ProcessLogQueryPlanInterrupt(void);
#endif /* EXPLAIN_H */
diff --git a/src/include/tcop/pquery.h b/src/include/tcop/pquery.h
index 227d24b9d60..d04de1f5566 100644
--- a/src/include/tcop/pquery.h
+++ b/src/include/tcop/pquery.h
@@ -22,7 +22,6 @@ struct PlannedStmt; /* avoid including plannodes.h here */
extern PGDLLIMPORT Portal ActivePortal;
extern PGDLLIMPORT QueryDesc *ActiveQueryDesc;
-extern PGDLLIMPORT QueryDesc *save_ActiveQueryDesc;
extern PortalStrategy ChoosePortalStrategy(List *stmts);
