feat: support ANSI CURRENT_DATE/CURRENT_TIME keywords (#18902)

* Support CURRENT_DATE/TIME keywords

* align current_time with ANSI TIME semantics

Author: BohuTANG

Cargo.toml

@@ -465,7 +465,7 @@ rmp-serde = "1.1.1"
 roaring = { version = "^0.10", features = ["serde"] }
 rotbl = { version = "0.2.9", features = [] }
 rust_decimal = "1.26"
-rustix = "0.38.37"
+rustix = { version = "0.38.37", features = ["fs"] }
 rustls = { version = "0.23.27", features = ["ring", "tls12"], default-features = false }
 rustls-pemfile = "2"
 rustls-pki-types = "1"

src/query/ast/src/parser/expr.rs

@@ -1499,6 +1499,34 @@ pub fn expr_element(i: Input) -> IResult<WithSpan<ExprElement>> {
         |(_, not, _, _)| ExprElement::IsDistinctFrom { not: not.is_some() },
     );
 
+    let current_date = map(consumed(rule! { CURRENT_DATE }), |(span, _)| {
+        ExprElement::FunctionCall {
+            func: FunctionCall {
+                distinct: false,
+                name: Identifier::from_name(transform_span(span.tokens), "current_date"),
+                args: vec![],
+                params: vec![],
+                order_by: vec![],
+                window: None,
+                lambda: None,
+            },
+        }
+    });
+
+    let current_time = map(consumed(rule! { CURRENT_TIME }), |(span, _)| {
+        ExprElement::FunctionCall {
+            func: FunctionCall {
+                distinct: false,
+                name: Identifier::from_name(transform_span(span.tokens), "current_time"),
+                args: vec![],
+                params: vec![],
+                order_by: vec![],
+                window: None,
+                lambda: None,
+            },
+        }
+    });
+
     let current_timestamp = map(consumed(rule! { CURRENT_TIMESTAMP }), |(span, _)| {
         ExprElement::FunctionCall {
             func: FunctionCall {
@@ -1573,6 +1601,8 @@ pub fn expr_element(i: Input) -> IResult<WithSpan<ExprElement>> {
                 | #dot_access : "<dot_access>"
                 | #map_access : "[<key>] | .<key> | :<key>"
                 | #literal : "<literal>"
+                | #current_date: "CURRENT_DATE"
+                | #current_time: "CURRENT_TIME"
                 | #current_timestamp: "CURRENT_TIMESTAMP"
                 | #array : "`[<expr>, ...]`"
                 | #map_expr : "`{ <literal> : <expr>, ... }`"

src/query/ast/src/parser/token.rs

@@ -497,10 +497,14 @@ pub enum TokenKind {
     CROSS,
     #[token("CSV", ignore(ascii_case))]
     CSV,
-    #[token("CURRENT", ignore(ascii_case))]
-    CURRENT,
+    #[token("CURRENT_DATE", ignore(ascii_case))]
+    CURRENT_DATE,
+    #[token("CURRENT_TIME", ignore(ascii_case))]
+    CURRENT_TIME,
     #[token("CURRENT_TIMESTAMP", ignore(ascii_case))]
     CURRENT_TIMESTAMP,
+    #[token("CURRENT", ignore(ascii_case))]
+    CURRENT,
     #[token("DATABASE", ignore(ascii_case))]
     DATABASE,
     #[token("DATABASES", ignore(ascii_case))]

src/query/functions/src/scalars/timestamp/src/datetime.rs

@@ -68,6 +68,7 @@ use databend_common_expression::vectorize_with_builder_1_arg;
 use databend_common_expression::vectorize_with_builder_2_arg;
 use databend_common_expression::vectorize_with_builder_4_arg;
 use databend_common_expression::EvalContext;
+use databend_common_expression::FunctionContext;
 use databend_common_expression::FunctionDomain;
 use databend_common_expression::FunctionProperty;
 use databend_common_expression::FunctionRegistry;
@@ -2101,13 +2102,50 @@ fn register_between_functions(registry: &mut FunctionRegistry) {
     ]);
 }
 
+fn normalize_time_precision(raw: i64) -> Result<u8, String> {
+    if (0..=9).contains(&raw) {
+        Ok(raw as u8)
+    } else {
+        Err(format!(
+            "Invalid fractional seconds precision `{raw}` for `current_time` (expect 0-9)"
+        ))
+    }
+}
+
+fn current_time_string(func_ctx: &FunctionContext, precision: Option<u8>) -> String {
+    let datetime = func_ctx.now.with_time_zone(func_ctx.tz.clone()).datetime();
+    let nanos = datetime.subsec_nanosecond() as u32;
+    let mut value = format!(
+        "{:02}:{:02}:{:02}",
+        datetime.hour(),
+        datetime.minute(),
+        datetime.second()
+    );
+
+    let precision = precision.unwrap_or(9).min(9);
+    if precision > 0 {
+        let divisor = 10_u32.pow(9 - precision as u32);
+        let truncated = nanos / divisor;
+        let frac = format!("{:0width$}", truncated, width = precision as usize);
+        value.push('.');
+        value.push_str(&frac);
+    }
+
+    value
+}
+
 fn register_real_time_functions(registry: &mut FunctionRegistry) {
     registry.register_aliases("now", &["current_timestamp"]);
+    registry.register_aliases("today", &["current_date"]);
 
     registry.properties.insert(
         "now".to_string(),
         FunctionProperty::default().non_deterministic(),
     );
+    registry.properties.insert(
+        "current_time".to_string(),
+        FunctionProperty::default().non_deterministic(),
+    );
     registry.properties.insert(
         "today".to_string(),
         FunctionProperty::default().non_deterministic(),
@@ -2153,6 +2191,28 @@ fn register_real_time_functions(registry: &mut FunctionRegistry) {
         |ctx| Value::Scalar(ctx.func_ctx.now.timestamp().as_microsecond()),
     );
 
+    registry.register_0_arg_core::<StringType, _, _>(
+        "current_time",
+        |_| FunctionDomain::Full,
+        |ctx| Value::Scalar(current_time_string(ctx.func_ctx, None)),
+    );
+
+    registry.register_passthrough_nullable_1_arg::<Int64Type, StringType, _, _>(
+        "current_time",
+        |_, _| FunctionDomain::MayThrow,
+        vectorize_with_builder_1_arg::<Int64Type, StringType>(|precision, output, ctx| {
+            match normalize_time_precision(precision) {
+                Ok(valid_precision) => {
+                    output.put_and_commit(current_time_string(ctx.func_ctx, Some(valid_precision)));
+                }
+                Err(err) => {
+                    ctx.set_error(output.len(), err);
+                    output.commit_row();
+                }
+            }
+        }),
+    );
+
     registry.register_0_arg_core::<DateType, _, _>(
         "today",
         |_| FunctionDomain::Full,

src/query/functions/tests/it/scalars/datetime.rs

@@ -13,12 +13,18 @@
 // limitations under the License.
 
 use std::io::Write;
+use std::str::FromStr;
 
 use databend_common_expression::types::*;
 use databend_common_expression::FromData;
+use databend_common_expression::FunctionContext;
 use goldenfile::Mint;
+use jiff::tz::TimeZone;
+use jiff::Timestamp;
 
 use super::run_ast;
+use super::run_ast_with_context;
+use super::TestContext;
 
 #[test]
 fn test_datetime() {
@@ -36,6 +42,7 @@ fn test_datetime() {
     test_to_number(file);
     test_rounder_functions(file);
     test_date_date_diff(file);
+    test_current_time(file);
 }
 
 fn test_to_timestamp(file: &mut impl Write) {
@@ -742,3 +749,24 @@ fn test_date_date_diff(file: &mut impl Write) {
         &[],
     );
 }
+
+fn test_current_time(file: &mut impl Write) {
+    let tz = TimeZone::UTC;
+    let now = Timestamp::from_str("2024-02-03T04:05:06.789123Z")
+        .unwrap()
+        .to_zoned(tz.clone());
+    let func_ctx = FunctionContext {
+        tz: tz.clone(),
+        now,
+        ..FunctionContext::default()
+    };
+    let ctx = TestContext {
+        func_ctx,
+        ..TestContext::default()
+    };
+
+    run_ast_with_context(file, "typeof(current_time())", ctx.clone());
+    run_ast_with_context(file, "current_time()", ctx.clone());
+    run_ast_with_context(file, "current_time(3)", ctx.clone());
+    run_ast_with_context(file, "current_time(10)", ctx);
+}

src/query/functions/tests/it/scalars/testdata/datetime.txt

@@ -3835,3 +3835,41 @@ output domain  : {-31622400..=-31622400}
 output         : -31622400
 
 
+ast            : typeof(current_time())
+raw expr       : typeof(current_time())
+checked expr   : typeof<T0=String><T0>(current_time<>())
+optimized expr : "VARCHAR"
+func ctx       : (modified)
+output type    : String
+output domain  : {"VARCHAR"..="VARCHAR"}
+output         : 'VARCHAR'
+
+
+ast            : current_time()
+raw expr       : current_time()
+checked expr   : current_time<>()
+optimized expr : "04:05:06.789123000"
+func ctx       : (modified)
+output type    : String
+output domain  : {"04:05:06.789123000"..="04:05:06.789123000"}
+output         : '04:05:06.789123000'
+
+
+ast            : current_time(3)
+raw expr       : current_time(3)
+checked expr   : current_time<Int64>(CAST<UInt8>(3_u8 AS Int64))
+optimized expr : "04:05:06.789"
+func ctx       : (modified)
+output type    : String
+output domain  : {"04:05:06.789"..="04:05:06.789"}
+output         : '04:05:06.789'
+
+
+error: 
+  --> SQL:1:1
+  |
+1 | current_time(10)
+  | ^^^^^^^^^^^^^^^^ Invalid fractional seconds precision `10` for `current_time` (expect 0-9) while evaluating function `current_time(10)` in expr `current_time(CAST(10 AS Int64))`
+
+
+

src/query/functions/tests/it/scalars/testdata/function_list.txt

@@ -19,6 +19,7 @@ ceiling -> ceil
 char_length -> length
 character_length -> length
 chr -> char
+current_date -> today
 current_timestamp -> now
 date -> to_date
 date_format -> to_string
@@ -1360,6 +1361,9 @@ Functions overloads:
 1 cot(Float64 NULL) :: Float64 NULL
 0 crc32(String) :: UInt32
 1 crc32(String NULL) :: UInt32 NULL
+0 current_time() :: String
+1 current_time(Int64) :: String
+2 current_time(Int64 NULL) :: String NULL
 0 date_add_months(Date, Int64) :: Date
 1 date_add_months(Date NULL, Int64 NULL) :: Date NULL
 2 date_add_months(Timestamp, Int64) :: Timestamp

tests/sqllogictests/suites/query/functions/02_0012_function_datetimes.test

@@ -222,6 +222,21 @@ select typeof(now() - now())
 ----
 BIGINT
 
+query TTT
+select typeof(CURRENT_DATE()), typeof(CURRENT_TIME()), typeof(CURRENT_TIMESTAMP())
+----
+DATE VARCHAR TIMESTAMP
+
+query B
+select regexp_like(CURRENT_TIME(), '^[0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]{1,9})?$')
+----
+1
+
+query B
+select regexp_like(CURRENT_TIME(3), '^[0-9]{2}:[0-9]{2}:[0-9]{2}\.\d{3}$')
+----
+1
+
 query B
 select typeof(to_unix_timestamp('2023-04-06 04:06:23.231808'))
 ----