Show GIDs of two-phase commit commands as constants in pg_stat_statements

michaelpq · michaelpq · commit 638d42a3c520 · 2023-08-12T10:44:15.000+09:00
This relies on the "location" field added to TransactionStmt in 31de7e6, now applied to the "gid" field used by 2PC commands. These commands are now reported like: COMMIT PREPARED $1 PREPARE TRANSACTION $1 ROLLBACK PREPARED $1 Applying constants for these commands is a huge advantage for workloads that rely a lot on 2PC commands with different GIDs. Some tests are added to track the new behavior. Reviewed-by: Julien Rouhaud Discussion: https://postgr.es/m/ZMhT9kNtJJsHw6jK@paquier.xyz
diff --git a/contrib/pg_stat_statements/expected/utility.out b/contrib/pg_stat_statements/expected/utility.out
@@ -197,6 +197,29 @@ SELECT pg_stat_statements_reset();
  
 (1 row)
 
+-- Two-phase transactions
+BEGIN;
+PREPARE TRANSACTION 'stat_trans1';
+COMMIT PREPARED 'stat_trans1';
+BEGIN;
+PREPARE TRANSACTION 'stat_trans2';
+ROLLBACK PREPARED 'stat_trans2';
+SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
+ calls | rows |               query               
+-------+------+-----------------------------------
+     2 |    0 | BEGIN
+     1 |    0 | COMMIT PREPARED $1
+     2 |    0 | PREPARE TRANSACTION $1
+     1 |    0 | ROLLBACK PREPARED $1
+     1 |    1 | SELECT pg_stat_statements_reset()
+(5 rows)
+
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
 -- Savepoints
 BEGIN;
 SAVEPOINT sp1;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.conf b/contrib/pg_stat_statements/pg_stat_statements.conf
@@ -1 +1,2 @@
 shared_preload_libraries = 'pg_stat_statements'
+max_prepared_transactions = 5
diff --git a/contrib/pg_stat_statements/sql/utility.sql b/contrib/pg_stat_statements/sql/utility.sql
@@ -115,6 +115,16 @@ COMMIT;
 SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
 
+-- Two-phase transactions
+BEGIN;
+PREPARE TRANSACTION 'stat_trans1';
+COMMIT PREPARED 'stat_trans1';
+BEGIN;
+PREPARE TRANSACTION 'stat_trans2';
+ROLLBACK PREPARED 'stat_trans2';
+SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
+SELECT pg_stat_statements_reset();
+
 -- Savepoints
 BEGIN;
 SAVEPOINT sp1;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
@@ -10924,7 +10924,7 @@ TransactionStmt:
 
 					n->kind = TRANS_STMT_PREPARE;
 					n->gid = $3;
-					n->location = -1;
+					n->location = @3;
 					$$ = (Node *) n;
 				}
 			| COMMIT PREPARED Sconst
@@ -10933,7 +10933,7 @@ TransactionStmt:
 
 					n->kind = TRANS_STMT_COMMIT_PREPARED;
 					n->gid = $3;
-					n->location = -1;
+					n->location = @3;
 					$$ = (Node *) n;
 				}
 			| ROLLBACK PREPARED Sconst
@@ -10942,7 +10942,7 @@ TransactionStmt:
 
 					n->kind = TRANS_STMT_ROLLBACK_PREPARED;
 					n->gid = $3;
-					n->location = -1;
+					n->location = @3;
 					$$ = (Node *) n;
 				}
 		;
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
@@ -3540,7 +3540,8 @@ typedef struct TransactionStmt
 	List	   *options;		/* for BEGIN/START commands */
 	/* for savepoint commands */
 	char	   *savepoint_name pg_node_attr(query_jumble_ignore);
-	char	   *gid;			/* for two-phase-commit related commands */
+	/* for two-phase-commit related commands */
+	char	   *gid pg_node_attr(query_jumble_ignore);
 	bool		chain;			/* AND CHAIN option */
 	/* token location, or -1 if unknown */
 	int			location pg_node_attr(query_jumble_location);

Original file line number	Diff line number	Diff line change
`@@ -1 +1,2 @@`
`1`	`1`	`shared_preload_libraries = 'pg_stat_statements'`
	`2`	`+max_prepared_transactions = 5`
Original file line number	Diff line number	Diff line change
`@@ -10924,7 +10924,7 @@ TransactionStmt:`
`10924`	`10924`
`10925`	`10925`	`n->kind = TRANS_STMT_PREPARE;`
`10926`	`10926`	`n->gid = $3;`
`10927`		`- n->location = -1;`
	`10927`	`+ n->location = @3;`
`10928`	`10928`	`$$ = (Node *) n;`
`10929`	`10929`	`}`
`10930`	`10930`	`\| COMMIT PREPARED Sconst`
`@@ -10933,7 +10933,7 @@ TransactionStmt:`
`10933`	`10933`
`10934`	`10934`	`n->kind = TRANS_STMT_COMMIT_PREPARED;`
`10935`	`10935`	`n->gid = $3;`
`10936`		`- n->location = -1;`
	`10936`	`+ n->location = @3;`
`10937`	`10937`	`$$ = (Node *) n;`
`10938`	`10938`	`}`
`10939`	`10939`	`\| ROLLBACK PREPARED Sconst`
`@@ -10942,7 +10942,7 @@ TransactionStmt:`
`10942`	`10942`
`10943`	`10943`	`n->kind = TRANS_STMT_ROLLBACK_PREPARED;`
`10944`	`10944`	`n->gid = $3;`
`10945`		`- n->location = -1;`
	`10945`	`+ n->location = @3;`
`10946`	`10946`	`$$ = (Node *) n;`
`10947`	`10947`	`}`
`10948`	`10948`	`;`