Use query execution start time as the value of now-like functions.

core/src/main/java/org/opensearch/sql/analysis/AnalysisContext.java

@@ -7,13 +7,11 @@
 package org.opensearch.sql.analysis;
 
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 import java.util.Objects;
 import lombok.Getter;
-import org.opensearch.sql.expression.Expression;
 import org.opensearch.sql.expression.NamedExpression;
+import org.opensearch.sql.expression.function.FunctionProperties;
 
 /**
  * The context used for Analyzer.
@@ -26,13 +24,8 @@ public class AnalysisContext {
   @Getter
   private final List<NamedExpression> namedParseExpressions;
 
-  /**
-   * Storage for values of functions which return a constant value.
-   * We are storing the values there to use it in sequential calls to those functions.
-   * For example, `now` function should the same value during processing a query.
-   */
   @Getter
-  private final Map<String, Expression> constantFunctionValues;
+  private final FunctionProperties functionProperties;
 
   public AnalysisContext() {
     this(new TypeEnvironment(null));
@@ -45,7 +38,7 @@ public AnalysisContext() {
   public AnalysisContext(TypeEnvironment environment) {
     this.environment = environment;
     this.namedParseExpressions = new ArrayList<>();
-    this.constantFunctionValues = new HashMap<>();
+    this.functionProperties = new FunctionProperties();
   }
 
   /**

core/src/main/java/org/opensearch/sql/analysis/Analyzer.java

@@ -196,7 +196,7 @@ public LogicalPlan visitTableFunction(TableFunction node, AnalysisContext contex
         .map(unresolvedExpression -> this.expressionAnalyzer.analyze(unresolvedExpression, context))
         .collect(Collectors.toList());
     TableFunctionImplementation tableFunctionImplementation
-        = (TableFunctionImplementation) repository.compile(
+        = (TableFunctionImplementation) repository.compile(context.getFunctionProperties(),
         dataSourceSchemaIdentifierNameResolver.getDataSourceName(), functionName, arguments);
     context.push();
     TypeEnvironment curEnv = context.peek();

core/src/main/java/org/opensearch/sql/analysis/ExpressionAnalyzer.java

@@ -25,7 +25,6 @@
 import org.opensearch.sql.ast.expression.Case;
 import org.opensearch.sql.ast.expression.Cast;
 import org.opensearch.sql.ast.expression.Compare;
-import org.opensearch.sql.ast.expression.ConstantFunction;
 import org.opensearch.sql.ast.expression.EqualTo;
 import org.opensearch.sql.ast.expression.Field;
 import org.opensearch.sql.ast.expression.Function;
@@ -78,7 +77,8 @@ public class ExpressionAnalyzer extends AbstractNodeVisitor<Expression, Analysis
   public Expression visitCast(Cast node, AnalysisContext context) {
     final Expression expression = node.getExpression().accept(this, context);
     return (Expression) repository
-        .compile(node.convertFunctionName(), Collections.singletonList(expression));
+        .compile(context.getFunctionProperties(), node.convertFunctionName(),
+            Collections.singletonList(expression));
   }
 
   public ExpressionAnalyzer(
@@ -156,7 +156,7 @@ public Expression visitAggregateFunction(AggregateFunction node, AnalysisContext
         builder.add(arg.accept(this, context));
       }
       Aggregator aggregator = (Aggregator) repository.compile(
-              builtinFunctionName.get().getName(), builder.build());
+          context.getFunctionProperties(), builtinFunctionName.get().getName(), builder.build());
       aggregator.distinct(node.getDistinct());
       if (node.condition() != null) {
         aggregator.condition(analyze(node.condition(), context));
@@ -173,27 +173,15 @@ public Expression visitRelevanceFieldList(RelevanceFieldList node, AnalysisConte
         ImmutableMap.copyOf(node.getFieldList())));
   }
 
-  @Override
-  public Expression visitConstantFunction(ConstantFunction node, AnalysisContext context) {
-    var valueName = node.getFuncName();
-    if (context.getConstantFunctionValues().containsKey(valueName)) {
-      return context.getConstantFunctionValues().get(valueName);
-    }
-
-    var value = visitFunction(node, context);
-    value = DSL.literal(value.valueOf());
-    context.getConstantFunctionValues().put(valueName, value);
-    return value;
-  }
-
   @Override
   public Expression visitFunction(Function node, AnalysisContext context) {
     FunctionName functionName = FunctionName.of(node.getFuncName());
     List<Expression> arguments =
         node.getFuncArgs().stream()
             .map(unresolvedExpression -> analyze(unresolvedExpression, context))
             .collect(Collectors.toList());
-    return (Expression) repository.compile(functionName, arguments);
+    return (Expression) repository.compile(context.getFunctionProperties(),
+        functionName, arguments);
   }
 
   @SuppressWarnings("unchecked")
@@ -237,7 +225,8 @@ public Expression visitCompare(Compare node, AnalysisContext context) {
     Expression left = analyze(node.getLeft(), context);
     Expression right = analyze(node.getRight(), context);
     return (Expression)
-        repository.compile(functionName, Arrays.asList(left, right));
+        repository.compile(context.getFunctionProperties(),
+            functionName, Arrays.asList(left, right));
   }
 
   @Override

core/src/main/java/org/opensearch/sql/analysis/ExpressionReferenceOptimizer.java

@@ -70,7 +70,8 @@ public Expression visitFunction(FunctionExpression node, AnalysisContext context
       final List<Expression> args =
           node.getArguments().stream().map(expr -> expr.accept(this, context))
               .collect(Collectors.toList());
-      return (Expression) repository.compile(node.getFunctionName(), args);
+      return (Expression) repository.compile(context.getFunctionProperties(),
+          node.getFunctionName(), args);
     }
   }
 

core/src/main/java/org/opensearch/sql/ast/AbstractNodeVisitor.java

@@ -15,7 +15,6 @@
 import org.opensearch.sql.ast.expression.Case;
 import org.opensearch.sql.ast.expression.Cast;
 import org.opensearch.sql.ast.expression.Compare;
-import org.opensearch.sql.ast.expression.ConstantFunction;
 import org.opensearch.sql.ast.expression.EqualTo;
 import org.opensearch.sql.ast.expression.Field;
 import org.opensearch.sql.ast.expression.Function;
@@ -126,10 +125,6 @@ public T visitRelevanceFieldList(RelevanceFieldList node, C context) {
     return visitChildren(node, context);
   }
 
-  public T visitConstantFunction(ConstantFunction node, C context) {
-    return visitChildren(node, context);
-  }
-
   public T visitUnresolvedAttribute(UnresolvedAttribute node, C context) {
     return visitChildren(node, context);
   }

core/src/main/java/org/opensearch/sql/ast/dsl/AstDSL.java

@@ -19,7 +19,6 @@
 import org.opensearch.sql.ast.expression.Case;
 import org.opensearch.sql.ast.expression.Cast;
 import org.opensearch.sql.ast.expression.Compare;
-import org.opensearch.sql.ast.expression.ConstantFunction;
 import org.opensearch.sql.ast.expression.DataType;
 import org.opensearch.sql.ast.expression.EqualTo;
 import org.opensearch.sql.ast.expression.Field;
@@ -246,10 +245,6 @@ public static Function function(String funcName, UnresolvedExpression... funcArg
     return new Function(funcName, Arrays.asList(funcArgs));
   }
 
-  public static Function constantFunction(String funcName, UnresolvedExpression... funcArgs) {
-    return new ConstantFunction(funcName, Arrays.asList(funcArgs));
-  }
-
   /**
    * CASE
    *     WHEN search_condition THEN result_expr