When using JDBC persistence, paging seems to be ineffective. If an amount of data greater than `global-max-size` is stored to a queue, a message is shown in the log showing that paging has started. However, regardless how much data is stored, no files are written to the paging directory (which may not even be configured), nor is any additional data stored in the database.

The JDBC database schema includes a table which seems to be related to paging. The schema is as follows:

QL> desc mp;
 Name                       Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                       NOT NULL NUMBER(19)
 FILENAME                        VARCHAR2(255)
 EXTENSION                        VARCHAR2(10)
 DATA                            BLOB
 

It is not clear whether the table should store the actual paging data, or just references to files on disk. However, the number of records in this table do not increase, however much data is stored.

The consequence is that broker fails to start, if there is too much data in the message store to load into the heap at start-up.