sql: add pg_backend_pid column to crdb_internal.{node, cluster}_sessions

Fixes #98581.
Informs #95771.

This commit adds a new pg_backend_pid column to the
crdb_internal.node_sessions and crdb_internal.cluster_sessions tables.

Release note (sql change): A pg_backend_pid column was added to
crdb_internal.node_sessions and crdb_internal.cluster_sessions. This
value corresponds to the numerical ID returned from pg_backend_pid().

docs/generated/http/full.md

@@ -2119,6 +2119,7 @@ Session represents one SQL session.
 | num_txns_executed | [int32](#cockroach.server.serverpb.ListSessionsResponse-int32) |  | Count of the number of transactions that have been opened on this session. This count includes transactions that are in progress. | [reserved](#support-status) |
 | txn_fingerprint_ids | [uint64](#cockroach.server.serverpb.ListSessionsResponse-uint64) | repeated | List of transaction fingerprint IDs in this session. | [reserved](#support-status) |
 | total_active_time | [google.protobuf.Duration](#cockroach.server.serverpb.ListSessionsResponse-google.protobuf.Duration) |  | The session's total active time. | [reserved](#support-status) |
+| pg_backend_pid | [uint32](#cockroach.server.serverpb.ListSessionsResponse-uint32) |  | The Postgres backend PID of the session. | [reserved](#support-status) |
 
 
 
@@ -2265,6 +2266,7 @@ Session represents one SQL session.
 | num_txns_executed | [int32](#cockroach.server.serverpb.ListSessionsResponse-int32) |  | Count of the number of transactions that have been opened on this session. This count includes transactions that are in progress. | [reserved](#support-status) |
 | txn_fingerprint_ids | [uint64](#cockroach.server.serverpb.ListSessionsResponse-uint64) | repeated | List of transaction fingerprint IDs in this session. | [reserved](#support-status) |
 | total_active_time | [google.protobuf.Duration](#cockroach.server.serverpb.ListSessionsResponse-google.protobuf.Duration) |  | The session's total active time. | [reserved](#support-status) |
+| pg_backend_pid | [uint32](#cockroach.server.serverpb.ListSessionsResponse-uint32) |  | The Postgres backend PID of the session. | [reserved](#support-status) |
 
 
 

pkg/ccl/logictestccl/testdata/logic_test/crdb_internal_tenant

@@ -263,15 +263,15 @@ SELECT  * FROM crdb_internal.cluster_transactions WHERE node_id < 0
 ----
 id  node_id  session_id  start  txn_string  application_name  num_stmts  num_retries  num_auto_retries  last_auto_retry_reason  isolation_level  priority  quality_of_service
 
-query ITTTTTTTTTTTTTT colnames
+query ITTTTTTTTTTTTTTT colnames
 SELECT * FROM crdb_internal.node_sessions WHERE node_id < 0
 ----
-node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end
+node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end  pg_backend_pid
 
-query ITTTTTTTTTTTTTT colnames
+query ITTTTTTTTTTTTTTT colnames
 SELECT * FROM crdb_internal.cluster_sessions WHERE node_id < 0
 ----
-node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end
+node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end  pg_backend_pid
 
 query IIITTTI colnames
 SELECT * FROM crdb_internal.node_contention_events WHERE table_id < 0

pkg/server/serverpb/status.proto

@@ -1048,6 +1048,9 @@ message Session {
   // The session's total active time.
   google.protobuf.Duration total_active_time = 18 [(gogoproto.nullable) = false,
     (gogoproto.stdduration) = true];
+
+  // The Postgres backend PID of the session.
+  uint32 pg_backend_pid = 19 [ (gogoproto.customname) = "PGBackendPID" ];
 }
 
 // An error wrapper object for ListSessionsResponse.

pkg/sql/conn_executor.go

@@ -4171,6 +4171,7 @@ func (ex *connExecutor) serialize() serverpb.Session {
 		LastActiveQueryNoConstants: lastActiveQueryNoConstants,
 		Status:                     status,
 		TotalActiveTime:            sessionActiveTime,
+		PGBackendPID:               ex.planner.extendedEvalCtx.QueryCancelKey.GetPGBackendPID(),
 	}
 }
 

pkg/sql/crdb_internal.go

@@ -2809,7 +2809,8 @@ CREATE TABLE crdb_internal.%s (
   alloc_bytes        INT,            -- the number of bytes allocated by the session
   max_alloc_bytes    INT,            -- the high water mark of bytes allocated by the session
   status             STRING,         -- the status of the session (open, closed)
-  session_end        TIMESTAMPTZ     -- the time when the session was closed
+  session_end        TIMESTAMPTZ,    -- the time when the session was closed
+  pg_backend_pid     INT             -- the postgres backend PID of the session
 )
 `
 
@@ -2910,6 +2911,7 @@ func populateSessionsTable(
 			tree.NewDInt(tree.DInt(session.MaxAllocBytes)),
 			tree.NewDString(session.Status.String()),
 			endTSDatum,
+			tree.NewDInt(tree.DInt(session.PGBackendPID)),
 		); err != nil {
 			return err
 		}
@@ -2935,7 +2937,8 @@ func populateSessionsTable(
 				tree.DNull,                             // alloc_bytes
 				tree.DNull,                             // max_alloc_bytes
 				tree.DNull,                             // status
-				tree.DNull,                             // session end
+				tree.DNull,                             // session_end
+				tree.DNull,                             // pg_backend_pid
 			); err != nil {
 				return err
 			}

pkg/sql/logictest/testdata/logic_test/crdb_internal

@@ -447,15 +447,15 @@ user root
 statement ok
 REVOKE SYSTEM VIEWACTIVITYREDACTED FROM testuser
 
-query ITTTTTTTTTTTTTT colnames
+query ITTTTTTTTTTTTTTT colnames
 SELECT * FROM crdb_internal.node_sessions WHERE node_id < 0
 ----
-node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end
+node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end  pg_backend_pid
 
-query ITTTTTTTTTTTTTT colnames
+query ITTTTTTTTTTTTTTT colnames
 SELECT * FROM crdb_internal.cluster_sessions WHERE node_id < 0
 ----
-node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end
+node_id  session_id  user_name  client_address  application_name  active_queries  last_active_query  num_txns_executed  session_start  active_query_start  kv_txn  alloc_bytes  max_alloc_bytes  status  session_end  pg_backend_pid
 
 query IIITTTI colnames
 SELECT * FROM crdb_internal.node_contention_events WHERE table_id < 0