commit 29dc2847f6255541992f18faf8a815dfab79631a
Author: Tristan Partin <tristan.partin@databricks.com>
Date:   2025-06-23 02:09:31 +0000

    Disable logging in parallel workers
    
    When a query uses parallel workers, pgaudit will log the same query for
    every parallel worker. This is undesireable since it can result in log
    amplification for queries that use parallel workers.
    
    Signed-off-by: Tristan Partin <tristan.partin@databricks.com>

diff --git a/expected/pgaudit.out b/expected/pgaudit.out
index b22560b..73f0327 100644
--- a/expected/pgaudit.out
+++ b/expected/pgaudit.out
@@ -2563,6 +2563,37 @@ COMMIT;
 NOTICE:  AUDIT: SESSION,12,4,MISC,COMMIT,,,COMMIT;,<not logged>
 DROP TABLE part_test;
 NOTICE:  AUDIT: SESSION,13,1,DDL,DROP TABLE,,,DROP TABLE part_test;,<not logged>
+--
+-- Test logging in parallel workers
+SET pgaudit.log = 'read';
+SET pgaudit.log_client = on;
+SET pgaudit.log_level = 'notice';
+-- Force parallel execution for testing
+SET max_parallel_workers_per_gather = 2;
+SET parallel_tuple_cost = 0;
+SET parallel_setup_cost = 0;
+SET min_parallel_table_scan_size = 0;
+SET min_parallel_index_scan_size = 0;
+-- Create table with enough data to trigger parallel execution
+CREATE TABLE parallel_test (id int, data text);
+INSERT INTO parallel_test SELECT generate_series(1, 1000), 'test data';
+SELECT count(*) FROM parallel_test;
+NOTICE:  AUDIT: SESSION,14,1,READ,SELECT,,,SELECT count(*) FROM parallel_test;,<not logged>
+ count 
+-------
+  1000
+(1 row)
+
+-- Cleanup parallel test
+DROP TABLE parallel_test;
+RESET max_parallel_workers_per_gather;
+RESET parallel_tuple_cost;
+RESET parallel_setup_cost;
+RESET min_parallel_table_scan_size;
+RESET min_parallel_index_scan_size;
+RESET pgaudit.log;
+RESET pgaudit.log_client;
+RESET pgaudit.log_level;
 -- Cleanup
 -- Set client_min_messages up to warning to avoid noise
 SET client_min_messages = 'warning';
diff --git a/pgaudit.c b/pgaudit.c
index 5e6fd38..ac9ded2 100644
--- a/pgaudit.c
+++ b/pgaudit.c
@@ -11,6 +11,7 @@
 #include "postgres.h"
 
 #include "access/htup_details.h"
+#include "access/parallel.h"
 #include "access/sysattr.h"
 #include "access/xact.h"
 #include "access/relation.h"
@@ -1303,7 +1304,7 @@ pgaudit_ExecutorStart_hook(QueryDesc *queryDesc, int eflags)
 {
     AuditEventStackItem *stackItem = NULL;
 
-    if (!internalStatement)
+    if (!internalStatement && !IsParallelWorker())
     {
         /* Push the audit even onto the stack */
         stackItem = stack_push();
@@ -1384,7 +1385,7 @@ pgaudit_ExecutorCheckPerms_hook(List *rangeTabls, bool abort)
 
     /* Log DML if the audit role is valid or session logging is enabled */
     if ((auditOid != InvalidOid || auditLogBitmap != 0) &&
-        !IsAbortedTransactionBlockState())
+        !IsAbortedTransactionBlockState() && !IsParallelWorker())
     {
         /* If auditLogRows is on, wait for rows processed to be set */
         if (auditLogRows && auditEventStack != NULL)
@@ -1438,7 +1439,7 @@ pgaudit_ExecutorRun_hook(QueryDesc *queryDesc, ScanDirection direction, uint64 c
     else
         standard_ExecutorRun(queryDesc, direction, count, execute_once);
 
-    if (auditLogRows && !internalStatement)
+    if (auditLogRows && !internalStatement && !IsParallelWorker())
     {
         /* Find an item from the stack by the query memory context */
         stackItem = stack_find_context(queryDesc->estate->es_query_cxt);
@@ -1458,7 +1459,7 @@ pgaudit_ExecutorEnd_hook(QueryDesc *queryDesc)
     AuditEventStackItem *stackItem = NULL;
     AuditEventStackItem *auditEventStackFull = NULL;
 
-    if (auditLogRows && !internalStatement)
+    if (auditLogRows && !internalStatement && !IsParallelWorker())
     {
         /* Find an item from the stack by the query memory context */
         stackItem = stack_find_context(queryDesc->estate->es_query_cxt);
diff --git a/sql/pgaudit.sql b/sql/pgaudit.sql
index 8052426..7f0667b 100644
--- a/sql/pgaudit.sql
+++ b/sql/pgaudit.sql
@@ -1612,6 +1612,36 @@ COMMIT;
 
 DROP TABLE part_test;
 
+--
+-- Test logging in parallel workers
+SET pgaudit.log = 'read';
+SET pgaudit.log_client = on;
+SET pgaudit.log_level = 'notice';
+
+-- Force parallel execution for testing
+SET max_parallel_workers_per_gather = 2;
+SET parallel_tuple_cost = 0;
+SET parallel_setup_cost = 0;
+SET min_parallel_table_scan_size = 0;
+SET min_parallel_index_scan_size = 0;
+
+-- Create table with enough data to trigger parallel execution
+CREATE TABLE parallel_test (id int, data text);
+INSERT INTO parallel_test SELECT generate_series(1, 1000), 'test data';
+
+SELECT count(*) FROM parallel_test;
+
+-- Cleanup parallel test
+DROP TABLE parallel_test;
+RESET max_parallel_workers_per_gather;
+RESET parallel_tuple_cost;
+RESET parallel_setup_cost;
+RESET min_parallel_table_scan_size;
+RESET min_parallel_index_scan_size;
+RESET pgaudit.log;
+RESET pgaudit.log_client;
+RESET pgaudit.log_level;
+
 -- Cleanup
 -- Set client_min_messages up to warning to avoid noise
 SET client_min_messages = 'warning';