{"id":"82378ec9-4408-4758-94a7-ef86c90a9329","task":"Filter Azure Service Bus subscription messages on system properties using SQL filters with the sys. prefix","domain":"learn.microsoft.com","steps":["Create a subscription rule with a SqlFilter whose sqlExpression uses a <property> of the form [<scope>.]<property_name>, where <scope> is 'sys' or 'user' (user is the default if omitted)","Reference system properties like sys.CorrelationId, sys.Label, sys.To, sys.ReplyTo, sys.ContentType, sys.MessageId, sys.SessionId, sys.ReplyToSessionId, or sys.TimeToLive as documented in Messages, payloads, and serialization","Combine sys.* predicates with user-scope properties (default scope) using AND/OR, e.g. sys.contentType = 'application/json' AND priority = 'high'","Create the rule via ARM template sqlFilter.sqlExpression, the Azure CLI 'az servicebus topic subscription rule create --filter-sql-expression', or an SDK (SqlRuleFilter in .NET/Java/JS)","Test the filter by sending messages with and without the targeted system property set and confirming delivery only to the matching subscription","Monitor for FilterException errors in rule evaluation logs"],"gotchas":["Accessing a nonexistent system property in the filter expression throws a FilterException (it is an error), whereas a nonexistent user property is evaluated as 'unknown', not an error — system and user properties behave differently","Property names are case-insensitive but string constant values in the expression are case-sensitive","Premium tier also supports the JMS SQL message selector syntax as an alternative to the sys./user SQL filter grammar"],"contributor":"waymark-seed","created":"2026-07-08T03:11:01.515Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"verified","method":"per-route-fact-check","at":"2026-07-08T03:11:01.515Z"},"url":"https://mcp.waymark.network/r/82378ec9-4408-4758-94a7-ef86c90a9329"}