direct path read: Wait: session reading blocks directly into PGA bypassing buffer cache

What does it mean?

The session spends time in this wait event while reading blocks directly into PGA memory rather than through the database buffer cache. It is usually associated with large full table scans and parallel queries.

Why does it happen?

Many blocks read from disk because of full scans of large tables, parallel queries, sort/hash operations spilling to the temporary tablespace, the serial direct path read decision for serial full scans, and queries that cannot use an index.

How to fix it

Identify SQL performing heavy full scans with AWR/ASH and add appropriate indexes. Reduce unnecessary scans of large tables through query tuning. Investigate storage latency (I/O) and move to faster disks if needed. Review the degree of parallelism. For operations spilling to TEMP, evaluate the PGA_AGGREGATE_TARGET size.