builtins: add CURRENT_TIME functionality

This PR adds CURRENT_TIME as a builtin.

Release note (sql change): This PR adds the CURRENT_TIME builtin, which
can be used with precision, e.g. `SELECT CURRENT_TIME, CURRENT_TIME(3)`.

docs/generated/sql/bnf/stmt_block.bnf

@@ -2130,6 +2130,7 @@ func_expr_common_subexpr ::=
 	| 'CURRENT_SCHEMA'
 	| 'CURRENT_CATALOG'
 	| 'CURRENT_TIMESTAMP'
+	| 'CURRENT_TIME'
 	| 'CURRENT_USER'
 	| 'CURRENT_ROLE'
 	| 'SESSION_USER'
@@ -2310,6 +2311,8 @@ special_function ::=
 	| 'CURRENT_SCHEMA' '(' ')'
 	| 'CURRENT_TIMESTAMP' '(' ')'
 	| 'CURRENT_TIMESTAMP' '(' a_expr ')'
+	| 'CURRENT_TIME' '(' ')'
+	| 'CURRENT_TIME' '(' a_expr ')'
 	| 'CURRENT_USER' '(' ')'
 	| 'EXTRACT' '(' extract_list ')'
 	| 'EXTRACT_DURATION' '(' extract_list ')'

docs/generated/sql/functions.md

@@ -1056,6 +1056,21 @@ SELECT * FROM crdb_internal.check_consistency(true, ‘\x02’, ‘\x04’)</p>
 </span></td></tr></tbody>
 </table>
 
+### TIMETZ functions
+
+<table>
+<thead><tr><th>Function &rarr; Returns</th><th>Description</th></tr></thead>
+<tbody>
+<tr><td><a name="current_time"></a><code>current_time() &rarr; <a href="time.html">time</a></code></td><td><span class="funcdesc"><p>Returns the current transaction’s time with no time zone.</p>
+</span></td></tr>
+<tr><td><a name="current_time"></a><code>current_time() &rarr; timetz</code></td><td><span class="funcdesc"><p>Returns the current transaction’s time with time zone.</p>
+</span></td></tr>
+<tr><td><a name="current_time"></a><code>current_time(precision: <a href="int.html">int</a>) &rarr; <a href="time.html">time</a></code></td><td><span class="funcdesc"><p>Returns the current transaction’s time with no time zone.</p>
+</span></td></tr>
+<tr><td><a name="current_time"></a><code>current_time(precision: <a href="int.html">int</a>) &rarr; timetz</code></td><td><span class="funcdesc"><p>Returns the current transaction’s time with time zone.</p>
+</span></td></tr></tbody>
+</table>
+
 ### TUPLE functions
 
 <table>

pkg/cmd/roachtest/hibernate_blacklist.go

@@ -23,7 +23,6 @@ var hibernateBlacklists = blacklistsForVersion{
 // After a failed run, an updated version of this blacklist should be available
 // in the test log.
 var hibernateBlackList20_1 = blacklist{
-	"org.hibernate.jpa.test.criteria.QueryBuilderTest.testDateTimeFunctions":                                                                                                    "31708",
 	"org.hibernate.jpa.test.criteria.basic.PredicateTest.testQuotientConversion":                                                                                                "26732",
 	"org.hibernate.jpa.test.lock.LockTest.testFindWithTimeoutHint":                                                                                                              "40476",
 	"org.hibernate.jpa.test.lock.LockTest.testUpdateWithPessimisticReadLockSkipLocked":                                                                                          "40476",

pkg/sql/logictest/testdata/logic_test/time

@@ -419,3 +419,51 @@ query T
 SELECT '2001-01-01 01:24:00'::time
 ----
 0000-01-01 01:24:00 +0000 UTC
+
+subtest current_time_tests
+
+statement ok
+CREATE TABLE current_time_test (
+  id INTEGER PRIMARY KEY,
+  a TIME(3) DEFAULT CURRENT_TIME,
+  b TIME DEFAULT CURRENT_TIME
+)
+
+statement ok
+INSERT INTO current_time_test (id) VALUES (1)
+
+statement ok
+INSERT INTO current_time_test (id, a, b) VALUES
+  (2, current_time, current_time),
+  (3, current_time, current_time(3))
+
+query I
+SELECT id FROM current_time_test WHERE
+  ('1970-01-01 ' || b::string)::timestamp -
+  ('1970-01-01 ' || a::string)::timestamp
+> '1ms'::interval ORDER BY id ASC
+----
+
+# test that current_time is correct in different timezones.
+
+statement ok
+set time zone +3
+
+statement ok
+create table current_time_tzset_test (id integer, a time, b time)
+
+statement ok
+insert into current_time_tzset_test (id, a) values (1, current_time)
+
+statement ok
+set time zone 0
+
+statement ok
+update current_time_tzset_test set b = current_time
+
+# a was written at an interval 3 hours ahead, and should persist that way.
+# make sure they're roughly 3 hours apart.
+query I
+select id from current_time_tzset_test WHERE interval '2h59m' < a - b and a - b < interval '3h'
+----
+1

pkg/sql/logictest/testdata/logic_test/timetz

@@ -94,6 +94,51 @@ SELECT '2001-01-01 11:00+04:00'::timestamptz::timetz
 statement ok
 SET TIME ZONE UTC
 
+subtest current_time_tests
+
+# current_time cannot be subtracted, but can as a timestamp.
+query B
+select
+  ('1970-01-01 ' || current_time(3)::string)::timestamp -
+  ('1970-01-01 ' || current_time::string)::timestamp
+<= '1ms'::interval
+----
+true
+
+statement ok
+CREATE TABLE current_time_test (
+  id INTEGER PRIMARY KEY,
+  a TIMETZ(3) DEFAULT CURRENT_TIME,
+  b TIMETZ DEFAULT CURRENT_TIME
+)
+
+statement ok
+INSERT INTO current_time_test (id) VALUES (1)
+
+statement ok
+INSERT INTO current_time_test (id, a, b) VALUES
+  (2, current_time, current_time),
+  (3, current_time, current_time(3))
+
+query I
+SELECT id FROM current_time_test WHERE
+  ('1970-01-01 ' || b::string)::timestamp -
+  ('1970-01-01 ' || a::string)::timestamp
+> '1ms'::interval ORDER BY id ASC
+----
+
+# switching timezones should make current_time() change timezones too.
+statement ok
+set time zone +4
+
+query B
+select current_time() + current_timestamp()::date = current_timestamp()
+----
+true
+
+statement ok
+set time zone UTC
+
 subtest precision_tests
 
 query error precision 7 out of range

pkg/sql/parser/parse_test.go

@@ -1577,6 +1577,10 @@ func TestParse2(t *testing.T) {
 			`SELECT current_timestamp()`},
 		{`SELECT current_timestamp(6)`,
 			`SELECT current_timestamp(6)`},
+		{`SELECT CURRENT_TIME`,
+			`SELECT current_time()`},
+		{`SELECT current_time(6)`,
+			`SELECT current_time(6)`},
 		{`SELECT CURRENT_DATE`,
 			`SELECT current_date()`},
 		{`SELECT POSITION(a IN b)`,
@@ -3144,8 +3148,6 @@ func TestUnimplementedSyntax(t *testing.T) {
 		{`SELECT GROUPING (a,b,c)`, 0, `d_expr grouping`},
 		{`SELECT a(VARIADIC b)`, 0, `variadic`},
 		{`SELECT a(b, c, VARIADIC b)`, 0, `variadic`},
-		{`SELECT CURRENT_TIME`, 26097, `current_time`},
-		{`SELECT CURRENT_TIME()`, 26097, `current_time`},
 		{`SELECT TREAT (a AS INT8)`, 0, `treat`},
 		{`SELECT a(b) WITHIN GROUP (ORDER BY c)`, 0, `within group`},
 

pkg/sql/parser/sql.y

@@ -8201,7 +8201,7 @@ func_expr_common_subexpr:
   }
 | CURRENT_TIME
   {
-    return unimplementedWithIssueDetail(sqllex, 26097, "current_time")
+    $$.val = &tree.FuncExpr{Func: tree.WrapFunction($1)}
   }
 | CURRENT_USER
   {
@@ -8285,7 +8285,11 @@ special_function:
 | CURRENT_TIMESTAMP '(' error { return helpWithFunctionByName(sqllex, $1) }
 | CURRENT_TIME '(' ')'
   {
-    return unimplementedWithIssueDetail(sqllex, 26097, "current_time")
+    $$.val = &tree.FuncExpr{Func: tree.WrapFunction($1)}
+  }
+| CURRENT_TIME '(' a_expr ')'
+  {
+    $$.val = &tree.FuncExpr{Func: tree.WrapFunction($1), Exprs: tree.Exprs{$3.expr()}}
   }
 | CURRENT_TIME '(' error { return helpWithFunctionByName(sqllex, $1) }
 | CURRENT_USER '(' ')'

pkg/sql/sem/builtins/builtins.go

@@ -1674,7 +1674,52 @@ CockroachDB supports the following flags:
 		},
 	),
 
-	"now":                   txnTSImpl,
+	"now": txnTSImpl,
+	"current_time": makeBuiltin(
+		tree.FunctionProperties{Impure: true},
+		tree.Overload{
+			Types:             tree.ArgTypes{},
+			ReturnType:        tree.FixedReturnType(types.TimeTZ),
+			PreferredOverload: true,
+			Fn: func(ctx *tree.EvalContext, args tree.Datums) (tree.Datum, error) {
+				return ctx.GetTxnTime(time.Microsecond), nil
+			},
+			Info: "Returns the current transaction's time with time zone.",
+		},
+		tree.Overload{
+			Types:      tree.ArgTypes{},
+			ReturnType: tree.FixedReturnType(types.Time),
+			Fn: func(ctx *tree.EvalContext, args tree.Datums) (tree.Datum, error) {
+				return ctx.GetTxnTimeNoZone(time.Microsecond), nil
+			},
+			Info: "Returns the current transaction's time with no time zone.",
+		},
+		tree.Overload{
+			Types:             tree.ArgTypes{{"precision", types.Int}},
+			ReturnType:        tree.FixedReturnType(types.TimeTZ),
+			PreferredOverload: true,
+			Fn: func(ctx *tree.EvalContext, args tree.Datums) (tree.Datum, error) {
+				prec := int32(tree.MustBeDInt(args[0]))
+				if prec < 0 || prec > 6 {
+					return nil, pgerror.Newf(pgcode.NumericValueOutOfRange, "precision %d out of range", prec)
+				}
+				return ctx.GetTxnTime(tree.TimeFamilyPrecisionToRoundDuration(prec)), nil
+			},
+			Info: "Returns the current transaction's time with time zone.",
+		},
+		tree.Overload{
+			Types:      tree.ArgTypes{{"precision", types.Int}},
+			ReturnType: tree.FixedReturnType(types.Time),
+			Fn: func(ctx *tree.EvalContext, args tree.Datums) (tree.Datum, error) {
+				prec := int32(tree.MustBeDInt(args[0]))
+				if prec < 0 || prec > 6 {
+					return nil, pgerror.Newf(pgcode.NumericValueOutOfRange, "precision %d out of range", prec)
+				}
+				return ctx.GetTxnTimeNoZone(tree.TimeFamilyPrecisionToRoundDuration(prec)), nil
+			},
+			Info: "Returns the current transaction's time with no time zone.",
+		},
+	),
 	"current_timestamp":     txnTSWithPrecisionImpl,
 	"transaction_timestamp": txnTSImpl,
 

pkg/sql/sem/tree/eval.go

@@ -2946,6 +2946,28 @@ func (ctx *EvalContext) GetTxnTimestampNoZone(precision time.Duration) *DTimesta
 	return MakeDTimestamp(ctx.TxnTimestamp, precision)
 }
 
+// GetTxnTime retrieves the current transaction time as per
+// the evaluation context.
+func (ctx *EvalContext) GetTxnTime(precision time.Duration) *DTimeTZ {
+	// TODO(knz): a zero timestamp should never be read, even during
+	// Prepare. This will need to be addressed.
+	if !ctx.PrepareOnly && ctx.TxnTimestamp.IsZero() {
+		panic(errors.AssertionFailedf("zero transaction timestamp in EvalContext"))
+	}
+	return NewDTimeTZFromTime(ctx.GetRelativeParseTime().Round(precision))
+}
+
+// GetTxnTimeNoZone retrieves the current transaction time as per
+// the evaluation context.
+func (ctx *EvalContext) GetTxnTimeNoZone(precision time.Duration) *DTime {
+	// TODO(knz): a zero timestamp should never be read, even during
+	// Prepare. This will need to be addressed.
+	if !ctx.PrepareOnly && ctx.TxnTimestamp.IsZero() {
+		panic(errors.AssertionFailedf("zero transaction timestamp in EvalContext"))
+	}
+	return MakeDTime(timeofday.FromTime(ctx.GetRelativeParseTime().Round(precision)))
+}
+
 // SetTxnTimestamp sets the corresponding timestamp in the EvalContext.
 func (ctx *EvalContext) SetTxnTimestamp(ts time.Time) {
 	ctx.TxnTimestamp = ts