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michaelpqmichaelpq
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Show GIDs of two-phase commit commands as constants in pg_stat_statements
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
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+39
-4
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5 files changed

+39
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‎contrib/pg_stat_statements/expected/utility.out

+23
Original file line numberDiff line numberDiff line change
@@ -197,6 +197,29 @@ SELECT pg_stat_statements_reset();
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(1 row)
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-- Two-phase transactions
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BEGIN;
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PREPARE TRANSACTION 'stat_trans1';
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COMMIT PREPARED 'stat_trans1';
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BEGIN;
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PREPARE TRANSACTION 'stat_trans2';
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ROLLBACK PREPARED 'stat_trans2';
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SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
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calls | rows | query
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-------+------+-----------------------------------
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2 | 0 | BEGIN
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1 | 0 | COMMIT PREPARED $1
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2 | 0 | PREPARE TRANSACTION $1
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1 | 0 | ROLLBACK PREPARED $1
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1 | 1 | SELECT pg_stat_statements_reset()
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(5 rows)
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SELECT pg_stat_statements_reset();
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pg_stat_statements_reset
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--------------------------
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(1 row)
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-- Savepoints
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BEGIN;
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SAVEPOINT sp1;

‎contrib/pg_stat_statements/pg_stat_statements.conf

+1
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@@ -1 +1,2 @@
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shared_preload_libraries = 'pg_stat_statements'
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max_prepared_transactions = 5

‎contrib/pg_stat_statements/sql/utility.sql

+10
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@@ -115,6 +115,16 @@ COMMIT;
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SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
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SELECT pg_stat_statements_reset();
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-- Two-phase transactions
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BEGIN;
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PREPARE TRANSACTION 'stat_trans1';
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COMMIT PREPARED 'stat_trans1';
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BEGIN;
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PREPARE TRANSACTION 'stat_trans2';
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ROLLBACK PREPARED 'stat_trans2';
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SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
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SELECT pg_stat_statements_reset();
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-- Savepoints
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BEGIN;
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SAVEPOINT sp1;

‎src/backend/parser/gram.y

+3-3
Original file line numberDiff line numberDiff line change
@@ -10924,7 +10924,7 @@ TransactionStmt:
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n->kind = TRANS_STMT_PREPARE;
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n->gid = $3;
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n->location = -1;
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n->location = @3;
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$$ = (Node *) n;
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}
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| COMMIT PREPARED Sconst
@@ -10933,7 +10933,7 @@ TransactionStmt:
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n->kind = TRANS_STMT_COMMIT_PREPARED;
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n->gid = $3;
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n->location = -1;
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n->location = @3;
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$$ = (Node *) n;
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}
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| ROLLBACK PREPARED Sconst
@@ -10942,7 +10942,7 @@ TransactionStmt:
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n->kind = TRANS_STMT_ROLLBACK_PREPARED;
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n->gid = $3;
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n->location = -1;
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n->location = @3;
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$$ = (Node *) n;
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}
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;

‎src/include/nodes/parsenodes.h

+2-1
Original file line numberDiff line numberDiff line change
@@ -3540,7 +3540,8 @@ typedef struct TransactionStmt
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List *options; /* for BEGIN/START commands */
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/* for savepoint commands */
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char *savepoint_name pg_node_attr(query_jumble_ignore);
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char *gid; /* for two-phase-commit related commands */
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/* for two-phase-commit related commands */
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char *gid pg_node_attr(query_jumble_ignore);
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bool chain; /* AND CHAIN option */
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/* token location, or -1 if unknown */
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int location pg_node_attr(query_jumble_location);

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