pgbench: Fail cleanly when finding a COPY result state

Currently, pgbench aborts when a COPY response is received in
readCommandResponse().  However, as PQgetResult() returns an empty
result when there is no asynchronous result, through getCopyResult(),
the logic done at the end of readCommandResponse() for the error path
leads to an infinite loop.

This commit forcefully exits the COPY state with PQendcopy() before
moving to the error handler when fiding a COPY state, avoiding the
infinite loop.  The COPY protocol is not supported by pgbench anyway, as
an error is assumed in this case, so giving up is better than having the
tool be stuck forever.  pgbench was interruptible in this state.

A TAP test is added to check that an error happens if trying to use
COPY.

Author: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Discussion: https://postgr.es/m/CAO6_XqpHyF2m73ifV5a=5jhXxH2chk=XrgefY+eWWPe2Eft3=A@mail.gmail.com
Backpatch-through: 13

diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index a48126f8fa359caa370a79104ad51f7a3c169ad6..adf6e45953b22b5933cbd961437f4471bf551bdb 100644 (file)
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -3323,6 +3323,20 @@ readCommandResponse(CState *st, MetaCommand meta, char *varprefix)
                                                                 PQresultErrorMessage(res));
                                break;
 
+                       case PGRES_COPY_IN:
+                       case PGRES_COPY_OUT:
+                       case PGRES_COPY_BOTH:
+                               pg_log_error("COPY is not supported in pgbench, aborting");
+
+                               /*
+                                * We need to exit the copy state.  Otherwise, PQgetResult()
+                                * will always return an empty PGresult as an effect of
+                                * getCopyResult(), leading to an infinite loop in the error
+                                * cleanup done below.
+                                */
+                               PQendcopy(st->con);
+                               goto error;
+
                        case PGRES_NONFATAL_ERROR:
                        case PGRES_FATAL_ERROR:
                                st->estatus = getSQLErrorStatus(PQresultErrorField(res,

diff --git a/src/bin/pgbench/t/001_pgbench_with_server.pl b/src/bin/pgbench/t/001_pgbench_with_server.pl
index d746987b5303f67864c68f25032ba4030fc85cd9..2c6b70a2b946ec40e3d2267ad8ad886db05854c6 100644 (file)
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgbench_with_server.pl
@@ -1546,6 +1546,16 @@ SELECT pg_advisory_unlock_all();
 # Clean up
 $node->safe_psql('postgres', 'DROP TABLE first_client_table, xy;');
 
+# Test copy in pgbench
+$node->pgbench(
+       '-t 10',
+       2,
+       [],
+       [ qr{COPY is not supported in pgbench, aborting} ],
+       'Test copy in script',
+       {
+               '001_copy' => q{ COPY pgbench_accounts FROM stdin }
+       });
 
 # done
 $node->safe_psql('postgres', 'DROP TABLESPACE regress_pgbench_tap_1_ts');