diff options
| -rw-r--r-- | src/backend/tcop/utility.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c index 27fbf1f3aae..bf085aa93b2 100644 --- a/src/backend/tcop/utility.c +++ b/src/backend/tcop/utility.c @@ -803,6 +803,23 @@ standard_ProcessUtility(PlannedStmt *pstmt, ListenStmt *stmt = (ListenStmt *) parsetree; CheckRestrictedOperation("LISTEN"); + + /* + * We don't allow LISTEN in background processes, as there is + * no mechanism for them to collect NOTIFY messages, so they'd + * just block cleanout of the async SLRU indefinitely. + * (Authors of custom background workers could bypass this + * restriction by calling Async_Listen directly, but then it's + * on them to provide some mechanism to process the message + * queue.) Note there seems no reason to forbid UNLISTEN. + */ + if (MyBackendType != B_BACKEND) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + /* translator: %s is name of a SQL command, eg LISTEN */ + errmsg("cannot execute %s within a background process", + "LISTEN"))); + Async_Listen(stmt->conditionname); } break; |