diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index c6347cd6f84..7547e51b5ea 100644
--- a/doc/src/sgml/ref/psql-ref.sgml
+++ b/doc/src/sgml/ref/psql-ref.sgml
@@ -2478,6 +2478,18 @@ testdb=> \setenv LESS -imx4F
+
+ \watch [ seconds ]
+
+
+ Repeatedly execute the current query buffer (like \g)
+ until interrupted or the query fails. Wait the specified number of
+ seconds (default 2) between executions.
+
+
+
+
+
\x [ on | off | auto ]
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 33bc2a7e4c5..09939fda5dd 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -60,6 +60,7 @@ static bool do_edit(const char *filename_arg, PQExpBuffer query_buf,
int lineno, bool *edited);
static bool do_connect(char *dbname, char *user, char *host, char *port);
static bool do_shell(const char *command);
+static bool do_watch(PQExpBuffer query_buf, long sleep);
static bool lookup_function_oid(PGconn *conn, const char *desc, Oid *foid);
static bool get_create_function_cmd(PGconn *conn, Oid oid, PQExpBuffer buf);
static int strip_lineno_from_funcdesc(char *func);
@@ -1433,6 +1434,29 @@ exec_command(const char *cmd,
free(fname);
}
+ /* \watch -- execute a query every N seconds */
+ else if (strcmp(cmd, "watch") == 0)
+ {
+ char *opt = psql_scan_slash_option(scan_state,
+ OT_NORMAL, NULL, true);
+ long sleep = 2;
+
+ /* Convert optional sleep-length argument */
+ if (opt)
+ {
+ sleep = strtol(opt, NULL, 10);
+ if (sleep <= 0)
+ sleep = 1;
+ free(opt);
+ }
+
+ success = do_watch(query_buf, sleep);
+
+ /* Reset the query buffer as though for \r */
+ resetPQExpBuffer(query_buf);
+ psql_scan_reset(scan_state);
+ }
+
/* \x -- set or toggle expanded table representation */
else if (strcmp(cmd, "x") == 0)
{
@@ -2555,6 +2579,112 @@ do_shell(const char *command)
return true;
}
+/*
+ * do_watch -- handler for \watch
+ *
+ * We break this out of exec_command to avoid having to plaster "volatile"
+ * onto a bunch of exec_command's variables to silence stupider compilers.
+ */
+static bool
+do_watch(PQExpBuffer query_buf, long sleep)
+{
+ printQueryOpt myopt = pset.popt;
+ char title[50];
+
+ if (!query_buf || query_buf->len <= 0)
+ {
+ psql_error(_("\\watch cannot be used with an empty query\n"));
+ return false;
+ }
+
+ /*
+ * Set up rendering options, in particular, disable the pager, because
+ * nobody wants to be prompted while watching the output of 'watch'.
+ */
+ myopt.nullPrint = NULL;
+ myopt.topt.pager = 0;
+
+ for (;;)
+ {
+ PGresult *res;
+ time_t timer;
+ long i;
+
+ /*
+ * Prepare title for output. XXX would it be better to use the time
+ * of completion of the command?
+ */
+ timer = time(NULL);
+ snprintf(title, sizeof(title), _("Watch every %lds\t%s"),
+ sleep, asctime(localtime(&timer)));
+ myopt.title = title;
+
+ /*
+ * Run the query. We use PSQLexec, which is kind of cheating, but
+ * SendQuery doesn't let us suppress autocommit behavior.
+ */
+ res = PSQLexec(query_buf->data, false);
+
+ /* PSQLexec handles failure results and returns NULL */
+ if (res == NULL)
+ break;
+
+ /*
+ * If SIGINT is sent while the query is processing, PSQLexec will
+ * consume the interrupt. The user's intention, though, is to cancel
+ * the entire watch process, so detect a sent cancellation request and
+ * exit in this case.
+ */
+ if (cancel_pressed)
+ {
+ PQclear(res);
+ break;
+ }
+
+ switch (PQresultStatus(res))
+ {
+ case PGRES_TUPLES_OK:
+ printQuery(res, &myopt, pset.queryFout, pset.logfile);
+ break;
+
+ case PGRES_EMPTY_QUERY:
+ psql_error(_("\\watch cannot be used with an empty query\n"));
+ PQclear(res);
+ return false;
+
+ default:
+ /* should we fail for non-tuple-result commands? */
+ break;
+ }
+
+ PQclear(res);
+
+ /*
+ * Set up cancellation of 'watch' via SIGINT. We redo this each time
+ * through the loop since it's conceivable something inside PSQLexec
+ * could change sigint_interrupt_jmp.
+ */
+ if (sigsetjmp(sigint_interrupt_jmp, 1) != 0)
+ break;
+
+ /*
+ * Enable 'watch' cancellations and wait a while before running the
+ * query again. Break the sleep into short intervals since pg_usleep
+ * isn't interruptible on some platforms.
+ */
+ sigint_interrupt_enabled = true;
+ for (i = 0; i < sleep; i++)
+ {
+ pg_usleep(1000000L);
+ if (cancel_pressed)
+ break;
+ }
+ sigint_interrupt_enabled = false;
+ }
+
+ return true;
+}
+
/*
* This function takes a function description, e.g. "x" or "x(int)", and
* issues a query on the given connection to retrieve the function's OID
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index ccb307b791f..3c7442a0733 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -165,7 +165,7 @@ slashUsage(unsigned short int pager)
currdb = PQdb(pset.db);
- output = PageOutput(95, pager);
+ output = PageOutput(96, pager);
/* if you add/remove a line here, change the row count above */
@@ -175,6 +175,7 @@ slashUsage(unsigned short int pager)
fprintf(output, _(" \\gset [PREFIX] execute query and store results in psql variables\n"));
fprintf(output, _(" \\h [NAME] help on syntax of SQL commands, * for all commands\n"));
fprintf(output, _(" \\q quit psql\n"));
+ fprintf(output, _(" \\watch [SEC] execute query every SEC seconds\n"));
fprintf(output, "\n");
fprintf(output, _("Query Buffer\n"));
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index d2170308f7c..7d2c8126126 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -900,7 +900,7 @@ psql_completion(char *text, int start, int end)
"\\lo_import", "\\lo_export", "\\lo_list", "\\lo_unlink",
"\\o", "\\p", "\\password", "\\prompt", "\\pset", "\\q", "\\qecho", "\\r",
"\\set", "\\sf", "\\t", "\\T",
- "\\timing", "\\unset", "\\x", "\\w", "\\z", "\\!", NULL
+ "\\timing", "\\unset", "\\x", "\\w", "\\watch", "\\z", "\\!", NULL
};
(void) end; /* not used */