Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit1b62d0f

Browse files
committed
Allow psql to re-use connection parameters after a connection loss.
Instead of immediately PQfinish'ing a dead connection, save it asideso that we can still extract its parameters for \connect attempts.(This works because PQconninfo doesn't care whether the PGconn is inCONNECTION_BAD state.) This allows developers to reconnect withjust \c after a database crash and restart.It's tempting to use the same approach instead of closing the oldconnection after a failed non-interactive \connect command. However,that would not be very safe: consider a script containing\c db1 user1 live_server\c db2 user2 dead_server\c db3The script would be expecting to connect to db3 at dead_server, butif we re-use parameters from the first connection then it mightsuccessfully connect to db3 at live_server. This'd defeat the goalof not letting a script accidentally execute commands against thewrong database.Discussion:https://postgr.es/m/38464.1603394584@sss.pgh.pa.us
1 parent860593e commit1b62d0f

File tree

6 files changed

+73
-26
lines changed

6 files changed

+73
-26
lines changed

‎doc/src/sgml/ref/psql-ref.sgml

Lines changed: 14 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -931,12 +931,23 @@ testdb=>
931931
connection is closed.
932932
If the connection attempt fails (wrong user name, access
933933
denied, etc.), the previous connection will be kept if
934-
<application>psql</application> is in interactive mode. But when
935-
executing a non-interactive script, processing will
936-
immediately stop with an error. This distinction was chosen as
934+
<application>psql</application> is in interactive mode. But when
935+
executing a non-interactive script, the old connection is closed
936+
and an error is reported. That may or may not terminate the
937+
script; if it does not, all database-accessing commands will fail
938+
until another <literal>\connect</literal> command is successfully
939+
executed. This distinction was chosen as
937940
a user convenience against typos on the one hand, and a safety
938941
mechanism that scripts are not accidentally acting on the
939942
wrong database on the other hand.
943+
Note that whenever a <literal>\connect</literal> command attempts
944+
to re-use parameters, the values re-used are those of the last
945+
successful connection, not of any failed attempts made subsequently.
946+
However, in the case of a
947+
non-interactive <literal>\connect</literal> failure, no parameters
948+
are allowed to be re-used later, since the script would likely be
949+
expecting the values from the failed <literal>\connect</literal>
950+
to be re-used.
940951
</para>
941952

942953
<para>

‎src/bin/psql/command.c

Lines changed: 39 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -3060,26 +3060,28 @@ do_connect(enum trivalue reuse_previous_specification,
30603060
break;
30613061
}
30623062

3063-
/*
3064-
* If we are to re-use parameters, there'd better be an old connection to
3065-
* get them from.
3066-
*/
3067-
if (reuse_previous&& !o_conn)
3068-
{
3069-
pg_log_error("No database connection exists to re-use parameters from");
3070-
return false;
3071-
}
3072-
30733063
/*
30743064
* If we intend to re-use connection parameters, collect them out of the
3075-
* old connection, then replace individual values as necessary. Otherwise,
3076-
* obtain a PQconninfoOption array containing libpq's defaults, and modify
3077-
* that. Note this function assumes that PQconninfo, PQconndefaults, and
3078-
* PQconninfoParse will all produce arrays containing the same options in
3079-
* the same order.
3065+
* old connection, then replace individual values as necessary. (We may
3066+
* need to resort to looking at pset.dead_conn, if the connection died
3067+
* previously.) Otherwise, obtain a PQconninfoOption array containing
3068+
* libpq's defaults, and modify that. Note this function assumes that
3069+
* PQconninfo, PQconndefaults, and PQconninfoParse will all produce arrays
3070+
* containing the same options in the same order.
30803071
*/
30813072
if (reuse_previous)
3082-
cinfo=PQconninfo(o_conn);
3073+
{
3074+
if (o_conn)
3075+
cinfo=PQconninfo(o_conn);
3076+
elseif (pset.dead_conn)
3077+
cinfo=PQconninfo(pset.dead_conn);
3078+
else
3079+
{
3080+
/* This is reachable after a non-interactive \connect failure */
3081+
pg_log_error("No database connection exists to re-use parameters from");
3082+
return false;
3083+
}
3084+
}
30833085
else
30843086
cinfo=PQconndefaults();
30853087

@@ -3360,14 +3362,26 @@ do_connect(enum trivalue reuse_previous_specification,
33603362
if (o_conn)
33613363
{
33623364
/*
3363-
* Transition to having no connection. Keep this bit in sync
3364-
* with CheckConnection().
3365+
* Transition to having no connection.
3366+
*
3367+
* Unlike CheckConnection(), we close the old connection
3368+
* immediately to prevent its parameters from being re-used.
3369+
* This is so that a script cannot accidentally reuse
3370+
* parameters it did not expect to. Otherwise, the state
3371+
* cleanup should be the same as in CheckConnection().
33653372
*/
33663373
PQfinish(o_conn);
33673374
pset.db=NULL;
33683375
ResetCancelConn();
33693376
UnsyncVariables();
33703377
}
3378+
3379+
/* On the same reasoning, release any dead_conn to prevent reuse */
3380+
if (pset.dead_conn)
3381+
{
3382+
PQfinish(pset.dead_conn);
3383+
pset.dead_conn=NULL;
3384+
}
33713385
}
33723386

33733387
return false;
@@ -3421,8 +3435,15 @@ do_connect(enum trivalue reuse_previous_specification,
34213435
PQdb(pset.db),PQuser(pset.db));
34223436
}
34233437

3438+
/* Drop no-longer-needed connection(s) */
34243439
if (o_conn)
34253440
PQfinish(o_conn);
3441+
if (pset.dead_conn)
3442+
{
3443+
PQfinish(pset.dead_conn);
3444+
pset.dead_conn=NULL;
3445+
}
3446+
34263447
return true;
34273448
}
34283449

‎src/bin/psql/common.c

Lines changed: 7 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -313,10 +313,14 @@ CheckConnection(void)
313313
fprintf(stderr,_("Failed.\n"));
314314

315315
/*
316-
* Transition to having no connection. Keep this bit in sync with
317-
* do_connect().
316+
* Transition to having no connection; but stash away the failed
317+
* connection so that we can still refer to its parameters in a
318+
* later \connect attempt. Keep the state cleanup here in sync
319+
* with do_connect().
318320
*/
319-
PQfinish(pset.db);
321+
if (pset.dead_conn)
322+
PQfinish(pset.dead_conn);
323+
pset.dead_conn=pset.db;
320324
pset.db=NULL;
321325
ResetCancelConn();
322326
UnsyncVariables();

‎src/bin/psql/describe.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2744,7 +2744,7 @@ describeOneTableDetails(const char *schemaname,
27442744
/* Show the stats target if it's not default */
27452745
if (strcmp(PQgetvalue(result,i,8),"-1")!=0)
27462746
appendPQExpBuffer(&buf,"; STATISTICS %s",
2747-
PQgetvalue(result,i,8));
2747+
PQgetvalue(result,i,8));
27482748

27492749
printTableAddFooter(&cont,buf.data);
27502750
}

‎src/bin/psql/settings.h

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -117,6 +117,13 @@ typedef struct _psqlSettings
117117

118118
VariableSpacevars;/* "shell variable" repository */
119119

120+
/*
121+
* If we get a connection failure, the now-unusable PGconn is stashed here
122+
* until we can successfully reconnect. Never attempt to do anything with
123+
* this PGconn except extract parameters for a \connect attempt.
124+
*/
125+
PGconn*dead_conn;/* previous connection to backend */
126+
120127
/*
121128
* The remaining fields are set by assign hooks associated with entries in
122129
* "vars". They should not be set directly except by those hook

‎src/bin/psql/startup.c

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -145,6 +145,7 @@ main(int argc, char *argv[])
145145
pset.progname=get_progname(argv[0]);
146146

147147
pset.db=NULL;
148+
pset.dead_conn=NULL;
148149
setDecimalLocale();
149150
pset.encoding=PQenv2encoding();
150151
pset.queryFout=stdout;
@@ -442,7 +443,10 @@ main(int argc, char *argv[])
442443
/* clean up */
443444
if (pset.logfile)
444445
fclose(pset.logfile);
445-
PQfinish(pset.db);
446+
if (pset.db)
447+
PQfinish(pset.db);
448+
if (pset.dead_conn)
449+
PQfinish(pset.dead_conn);
446450
setQFout(NULL);
447451

448452
returnsuccessResult;

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp