Add wait events for COPY file/program operations#11
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Add wait events for COPY file/program operations#11NikolayS wants to merge 1 commit intoclaude/review-postgres-discussions-n0hWBfrom
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Add two new IO wait events: - COPY_DATA_READ: COPY FROM blocking on file or program read - COPY_DATA_WRITE: COPY TO blocking on file or program write This enables diagnosing: - Storage I/O bottlenecks during bulk loads (COPY FROM '/path/to/file') - Slow exports to files (COPY TO '/path/to/file') - Pipe buffer congestion in ETL pipelines (COPY FROM/TO PROGRAM) COPY FROM/TO STDIN/STDOUT already have coverage via Client/ClientRead and Client/ClientWrite at the protocol layer. These events are distinct from the existing COPY_FILE_READ/WRITE events, which instrument file-to-file copy operations in basebackup code. Example usage: -- Session 1: COPY large_table TO '/slow/nfs/mount/out.csv'; -- Session 2: SELECT wait_event, wait_event_type FROM pg_stat_activity WHERE pid = <session1_pid>; -- Shows: COPY_DATA_WRITE / IO
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Summary
COPY operations previously showed
wait_event = NULLwhen blocking on file/program I/O, making it impossible to diagnose performance issues during data loading, ETL operations, or pg_dump/pg_restore.This patch adds two new IO wait events:
COPY_DATA_READ: When COPY FROM blocks reading from file or programCOPY_DATA_WRITE: When COPY TO blocks writing to file or programCoverage
Note: STDIN/STDOUT already have coverage via
Client/ClientReadandClient/ClientWriteevents at the protocol layer.Use Cases
Changes
src/backend/commands/copyfromparse.c: Wrapfread()with wait eventssrc/backend/commands/copyto.c: Wrapfwrite()with wait eventssrc/backend/utils/activity/wait_event_names.txt: Add event definitions