diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index 182e58353f..d94e3cacfc 100644
--- a/doc/src/sgml/ref/psql-ref.sgml
+++ b/doc/src/sgml/ref/psql-ref.sgml
@@ -3566,13 +3566,14 @@ testdb=> \setenv LESS -imx4F
- \watch [ i[nterval]=seconds ] [ c[ount]=times ] [ seconds ]
+ \watch [ i[nterval]=seconds ] [ c[ount]=times ] [ m[in_rows]=rows ] [ seconds ]
Repeatedly execute the current query buffer (as \g does)
until interrupted, or the query fails, or the execution count limit
- (if given) is reached. Wait the specified number of
- seconds (default 2) between executions. For backwards compatibility,
+ (if given) is reached, or the query no longer returns the minimum number
+ of rows. Wait the specified number of seconds (default 2) between executions.
+ For backwards compatibility,
seconds can be specified
with or without an interval= prefix.
Each query result is
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 1300869d79..b5c914c2d4 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -162,7 +162,7 @@ static bool do_connect(enum trivalue reuse_previous_specification,
static bool do_edit(const char *filename_arg, PQExpBuffer query_buf,
int lineno, bool discard_on_quit, bool *edited);
static bool do_shell(const char *command);
-static bool do_watch(PQExpBuffer query_buf, double sleep, int iter);
+static bool do_watch(PQExpBuffer query_buf, double sleep, int iter, int min_rows);
static bool lookup_object_oid(EditableObjectType obj_type, const char *desc,
Oid *obj_oid);
static bool get_create_object_cmd(EditableObjectType obj_type, Oid oid,
@@ -2775,13 +2775,15 @@ exec_command_watch(PsqlScanState scan_state, bool active_branch,
{
bool have_sleep = false;
bool have_iter = false;
+ bool have_min_rows = false;
double sleep = 2;
int iter = 0;
+ int min_rows = 0;
/*
- * Parse arguments. We allow either an unlabeled interval or
- * "name=value", where name is from the set ('i', 'interval', 'c',
- * 'count').
+ * Parse arguments. We allow either an unlabeled interval,
+ * or "name=value", where name is from the set ('i', 'interval',
+ * 'c', 'count', 'm', 'min_rows').
*/
while (success)
{
@@ -2838,6 +2840,26 @@ exec_command_watch(PsqlScanState scan_state, bool active_branch,
}
}
}
+ else if (strncmp("m=", opt, strlen("m=")) == 0 ||
+ strncmp("min_rows=", opt, strlen("min_rows=")) == 0)
+ {
+ if (have_min_rows)
+ {
+ pg_log_error("\\watch: minimum row count specified more than once");
+ success = false;
+ }
+ else
+ {
+ have_min_rows = true;
+ errno = 0;
+ min_rows = strtoint(valptr, &opt_end, 10);
+ if (min_rows <= 0 || *opt_end || errno == ERANGE)
+ {
+ pg_log_error("\\watch: incorrect minimum row count \"%s\"", valptr);
+ success = false;
+ }
+ }
+ }
else
{
pg_log_error("\\watch: unrecognized parameter \"%s\"", opt);
@@ -2874,7 +2896,7 @@ exec_command_watch(PsqlScanState scan_state, bool active_branch,
/* If query_buf is empty, recall and execute previous query */
(void) copy_previous_query(query_buf, previous_buf);
- success = do_watch(query_buf, sleep, iter);
+ success = do_watch(query_buf, sleep, iter, min_rows);
}
/* Reset the query buffer as though for \r */
@@ -5144,7 +5166,7 @@ do_shell(const char *command)
* onto a bunch of exec_command's variables to silence stupider compilers.
*/
static bool
-do_watch(PQExpBuffer query_buf, double sleep, int iter)
+do_watch(PQExpBuffer query_buf, double sleep, int iter, int min_rows)
{
long sleep_ms = (long) (sleep * 1000);
printQueryOpt myopt = pset.popt;
@@ -5274,7 +5296,7 @@ do_watch(PQExpBuffer query_buf, double sleep, int iter)
myopt.title = title;
/* Run the query and print out the result */
- res = PSQLexecWatch(query_buf->data, &myopt, pagerpipe);
+ res = PSQLexecWatch(query_buf->data, &myopt, pagerpipe, min_rows);
/*
* PSQLexecWatch handles the case where we can no longer repeat the
diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 10ad1f2538..01efbfe1eb 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -36,6 +36,7 @@ static int ExecQueryAndProcessResults(const char *query,
double *elapsed_msec,
bool *svpt_gone_p,
bool is_watch,
+ int min_rows,
const printQueryOpt *opt,
FILE *printQueryFout);
static bool command_no_begin(const char *query);
@@ -632,7 +633,7 @@ PSQLexec(const char *query)
* e.g., because of the interrupt, -1 on error.
*/
int
-PSQLexecWatch(const char *query, const printQueryOpt *opt, FILE *printQueryFout)
+PSQLexecWatch(const char *query, const printQueryOpt *opt, FILE *printQueryFout, int min_rows)
{
bool timing = pset.timing;
double elapsed_msec = 0;
@@ -646,7 +647,7 @@ PSQLexecWatch(const char *query, const printQueryOpt *opt, FILE *printQueryFout)
SetCancelConn(pset.db);
- res = ExecQueryAndProcessResults(query, &elapsed_msec, NULL, true, opt, printQueryFout);
+ res = ExecQueryAndProcessResults(query, &elapsed_msec, NULL, true, min_rows, opt, printQueryFout);
ResetCancelConn();
@@ -1134,7 +1135,7 @@ SendQuery(const char *query)
pset.crosstab_flag || !is_select_command(query))
{
/* Default fetch-it-all-and-print mode */
- OK = (ExecQueryAndProcessResults(query, &elapsed_msec, &svpt_gone, false, NULL, NULL) > 0);
+ OK = (ExecQueryAndProcessResults(query, &elapsed_msec, &svpt_gone, false, 0, NULL, NULL) > 0);
}
else
{
@@ -1415,11 +1416,12 @@ DescribeQuery(const char *query, double *elapsed_msec)
static int
ExecQueryAndProcessResults(const char *query,
double *elapsed_msec, bool *svpt_gone_p,
- bool is_watch,
+ bool is_watch, int min_rows,
const printQueryOpt *opt, FILE *printQueryFout)
{
bool timing = pset.timing;
bool success;
+ bool return_early = false;
instr_time before,
after;
PGresult *result;
@@ -1461,6 +1463,10 @@ ExecQueryAndProcessResults(const char *query,
/* first result */
result = PQgetResult(pset.db);
+ if (min_rows > 0 && PQntuples(result) < min_rows)
+ {
+ return_early = true;
+ }
while (result != NULL)
{
@@ -1683,7 +1689,11 @@ ExecQueryAndProcessResults(const char *query,
if (!CheckConnection())
return -1;
- return cancel_pressed ? 0 : success ? 1 : -1;
+ if (cancel_pressed || return_early)
+ return 0;
+
+ return success ? 1 : -1;
+
}
diff --git a/src/bin/psql/common.h b/src/bin/psql/common.h
index 812b94a977..a16c56b405 100644
--- a/src/bin/psql/common.h
+++ b/src/bin/psql/common.h
@@ -32,7 +32,7 @@ extern void psql_setup_cancel_handler(void);
extern void SetShellResultVariables(int wait_result);
extern PGresult *PSQLexec(const char *query);
-extern int PSQLexecWatch(const char *query, const printQueryOpt *opt, FILE *printQueryFout);
+extern int PSQLexecWatch(const char *query, const printQueryOpt *opt, FILE *printQueryFout, int min_rows);
extern bool SendQuery(const char *query);
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index b2b749d69a..38c165a627 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -200,7 +200,9 @@ slashUsage(unsigned short int pager)
HELP0(" \\gset [PREFIX] execute query and store result in psql variables\n");
HELP0(" \\gx [(OPTIONS)] [FILE] as \\g, but forces expanded output mode\n");
HELP0(" \\q quit psql\n");
- HELP0(" \\watch [[i=]SEC] [c=N] execute query every SEC seconds, up to N times\n");
+ HELP0(" \\watch [[i=]SEC] [c=N] [m=MIN]\n");
+ HELP0(" execute query every SEC seconds, up to N times\n");
+ HELP0(" stop if less than MIN rows are returned\n");
HELP0("\n");
HELP0("Help\n");
diff --git a/src/bin/psql/t/001_basic.pl b/src/bin/psql/t/001_basic.pl
index 9ac27db212..35683b0f57 100644
--- a/src/bin/psql/t/001_basic.pl
+++ b/src/bin/psql/t/001_basic.pl
@@ -355,6 +355,28 @@ psql_like(
psql_like($node, sprintf('SELECT 1 \watch c=3 i=%g', 0.01),
qr/1\n1\n1/, '\watch with 3 iterations');
+# Check \watch minimum row count
+psql_fails_like(
+ $node,
+ 'SELECT 3 \watch m=x',
+ qr/incorrect minimum row count/,
+ '\watch, invalid minimum row setting');
+
+psql_fails_like(
+ $node,
+ 'SELECT 3 \watch m=1 min_rows=2',
+ qr/minimum row count specified more than once/,
+ '\watch, minimum rows is specified more than once');
+
+psql_like($node, q{with x as (select now()-backend_start AS howlong from pg_stat_activity where pid = pg_backend_pid()) select 123 from x where howlong < '2 seconds' \watch i=0.5 m=1},
+ qr/123\n123\n123/, '\watch, 1 minimum row');
+
+psql_like($node, q{with x as (select now()-backend_start AS howlong from pg_stat_activity where pid = pg_backend_pid()) select 123 from x where howlong < '2 seconds' \watch i=0.5 m=2},
+ qr/^123$/, '\watch, 2 minimum rows');
+
+psql_like($node, q{with x as (select now()-backend_start AS howlong from pg_stat_activity where pid = pg_backend_pid()) select 123 from x where howlong < '2 seconds' \watch i=0.5 min_rows=2},
+ qr/^123$/, '\watch, 2 minimum rows using min_rows=2');
+
# Check \watch errors
psql_fails_like(
$node,