Use COPY FREEZE in pgbench for faster benchmark table population.

tatsuo-ishii · tatsuo-ishii · commit 06ba4a63b85e · 2021-09-02T10:39:09.000+09:00
While populating the pgbench_accounts table, plain COPY was unconditionally used. By changing it to COPY FREEZE, the time for VACUUM is significantly reduced, thus the total time of "pgbench -i" is also reduced. This only happens if pgbench runs against PostgreSQL 14 or later because COPY FREEZE in previous versions of PostgreSQL does not bring the benefit. Also if partitioning is used, COPY FREEZE cannot be used. In this case plain COPY will be used too. Author: Tatsuo Ishii Discussion: https://postgr.es/m/20210308.143907.2014279678657453983.t-ishii@gmail.com Reviewed-by: Fabien COELHO, Laurenz Albe, Peter Geoghegan, Dean Rasheed
diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
@@ -220,6 +220,9 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
             data is generated in <command>pgbench</command> client and then
             sent to the server. This uses the client/server bandwidth
             extensively through a <command>COPY</command>.
+            <command>pgbench</command> uses the FREEZE option with 14 or later
+            versions of <productname>PostgreSQL</productname> to speed up
+            subsequent <command>VACUUM</command>, unless partitions are enabled.
             Using <literal>g</literal> causes logging to print one message
             every 100,000 rows while generating data for the
             <structname>pgbench_accounts</structname> table.
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
@@ -4153,6 +4153,7 @@ initGenerateDataClientSide(PGconn *con)
 	PGresult   *res;
 	int			i;
 	int64		k;
+	char		*copy_statement;
 
 	/* used to track elapsed time and estimate of the remaining time */
 	pg_time_usec_t start;
@@ -4199,7 +4200,15 @@ initGenerateDataClientSide(PGconn *con)
 	/*
 	 * accounts is big enough to be worth using COPY and tracking runtime
 	 */
-	res = PQexec(con, "copy pgbench_accounts from stdin");
+
+	/* use COPY with FREEZE on v14 and later without partioning */
+	if (partitions == 0 && PQserverVersion(con) >= 140000)
+		copy_statement = "copy pgbench_accounts from stdin with (freeze on)";
+	else
+		copy_statement = "copy pgbench_accounts from stdin";
+
+	res = PQexec(con, copy_statement);
+
 	if (PQresultStatus(res) != PGRES_COPY_IN)
 	{
 		pg_log_fatal("unexpected copy in result: %s", PQerrorMessage(con));
