Parallel Query Runs in Serial ON RAC when Using Default SERVICE_NAME
(Doc ID 2603641.1)
Last updated on FEBRUARY 25, 2022
Applies to:Oracle Database - Enterprise Edition - Version 220.127.116.11 and later
Information in this document applies to any platform.
- A query runs serially when connecting to the database using the default PDB SERVICE_NAME. It runs in parallel if connecting to the database using SID, or using a non-default SERVICE_NAME.
Example: select /*+ parallel(8) full(t) */ count(1) from <table> t;
The service can often be seen as active in the listener (lsnrctl status), but could also be absent.
The PDB name is not listed in gv$active_services, although it may be listed in gv$services.
- A PX trace shows that there are 0 instances available to run in parallel.
Example PX trace file:
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