Improvement CORE-5853 - Forward-compatible expressions LOCALTIME and …

…LOCALTIMESTAMP.

doc/README.time_zone_forward_compatibility.md

@@ -0,0 +1,13 @@
+# Time Zone support forward compatibility
+
+In version 4.0, Firebird will support time zones.
+
+Within this support will come an incompatibility with previous versions' `CURRENT_TIME` and `CURRENT_TIMESTAMP` expressions.
+
+In v4, `CURRENT_TIME` and `CURRENT_TIMESTAMP` will respectively return expressions of data type `TIME WITH TIME ZONE` and `TIMESTAMP WITH TIME ZONE`.
+
+To make your queries and database code compatible with future versions, from v3.0.4 you can instead use `LOCALTIME` and `LOCALTIMESTAMP`. In v3, these `LOCAL*` expressions will work indenticaly to their correspondents `CURRENT_*` expressions.
+
+In v4, `LOCAL*` expressions will continue to work identically as now, but the `CURRENT_*` expressions will change.
+
+You should not start using `LOCALTIME` and `LOCALTIMESTAMP` if your database may be downgraded to v3.0.3 or another version, as the old versions will not recognize the new expressions.

src/dsql/ExprNodes.cpp

@@ -3460,14 +3460,15 @@ dsc* CurrentDateNode::execute(thread_db* /*tdbb*/, jrd_req* request) const
 
 static RegisterNode<CurrentTimeNode> regCurrentTimeNode(blr_current_time);
 static RegisterNode<CurrentTimeNode> regCurrentTimeNode2(blr_current_time2);
+static RegisterNode<CurrentTimeNode> regCurrentTimeNode3(blr_local_time);
 
 DmlNode* CurrentTimeNode::parse(thread_db* /*tdbb*/, MemoryPool& pool, CompilerScratch* csb, const UCHAR blrOp)
 {
 	unsigned precision = DEFAULT_TIME_PRECISION;
 
-	fb_assert(blrOp == blr_current_time || blrOp == blr_current_time2);
+	fb_assert(blrOp == blr_current_time || blrOp == blr_current_time2 || blrOp == blr_local_time);
 
-	if (blrOp == blr_current_time2)
+	if (blrOp == blr_current_time2 || blrOp == blr_local_time)
 	{
 		precision = csb->csb_blr_reader.getByte();
 
@@ -3489,12 +3490,17 @@ string CurrentTimeNode::internalPrint(NodePrinter& printer) const
 
 void CurrentTimeNode::setParameterName(dsql_par* parameter) const
 {
-	parameter->par_name = parameter->par_alias = "CURRENT_TIME";
+	parameter->par_name = parameter->par_alias = dsqlLocal ? "LOCALTIME" : "CURRENT_TIME";
 }
 
 void CurrentTimeNode::genBlr(DsqlCompilerScratch* dsqlScratch)
 {
-	if (precision == DEFAULT_TIME_PRECISION)
+	if (dsqlLocal)
+	{
+		dsqlScratch->appendUChar(blr_local_time);
+		dsqlScratch->appendUChar(precision);
+	}
+	else if (precision == DEFAULT_TIME_PRECISION)
 		dsqlScratch->appendUChar(blr_current_time);
 	else
 	{
@@ -3572,15 +3578,16 @@ dsc* CurrentTimeNode::execute(thread_db* /*tdbb*/, jrd_req* request) const
 
 static RegisterNode<CurrentTimeStampNode> regCurrentTimeStampNode(blr_current_timestamp);
 static RegisterNode<CurrentTimeStampNode> regCurrentTimeStampNode2(blr_current_timestamp2);
+static RegisterNode<CurrentTimeStampNode> regCurrentTimeStampNode3(blr_local_timestamp);
 
 DmlNode* CurrentTimeStampNode::parse(thread_db* /*tdbb*/, MemoryPool& pool, CompilerScratch* csb,
 	const UCHAR blrOp)
 {
 	unsigned precision = DEFAULT_TIMESTAMP_PRECISION;
 
-	fb_assert(blrOp == blr_current_timestamp || blrOp == blr_current_timestamp2);
+	fb_assert(blrOp == blr_current_timestamp || blrOp == blr_current_timestamp2 || blrOp == blr_local_timestamp);
 
-	if (blrOp == blr_current_timestamp2)
+	if (blrOp == blr_current_timestamp2 || blrOp == blr_local_timestamp)
 	{
 		precision = csb->csb_blr_reader.getByte();
 
@@ -3602,12 +3609,17 @@ string CurrentTimeStampNode::internalPrint(NodePrinter& printer) const
 
 void CurrentTimeStampNode::setParameterName(dsql_par* parameter) const
 {
-	parameter->par_name = parameter->par_alias = "CURRENT_TIMESTAMP";
+	parameter->par_name = parameter->par_alias = dsqlLocal ? "LOCALTIMESTAMP" : "CURRENT_TIMESTAMP";
 }
 
 void CurrentTimeStampNode::genBlr(DsqlCompilerScratch* dsqlScratch)
 {
-	if (precision == DEFAULT_TIMESTAMP_PRECISION)
+	if (dsqlLocal)
+	{
+		dsqlScratch->appendUChar(blr_local_timestamp);
+		dsqlScratch->appendUChar(precision);
+	}
+	else if (precision == DEFAULT_TIMESTAMP_PRECISION)
 		dsqlScratch->appendUChar(blr_current_timestamp);
 	else
 	{

src/dsql/ExprNodes.h

@@ -340,7 +340,8 @@ class CurrentTimeNode : public TypedNode<ValueExprNode, ExprNode::TYPE_CURRENT_T
 public:
 	CurrentTimeNode(MemoryPool& pool, unsigned aPrecision)
 		: TypedNode<ValueExprNode, ExprNode::TYPE_CURRENT_TIME>(pool),
-		  precision(aPrecision)
+		  precision(aPrecision),
+		  dsqlLocal(false)
 	{
 	}
 
@@ -359,6 +360,7 @@ class CurrentTimeNode : public TypedNode<ValueExprNode, ExprNode::TYPE_CURRENT_T
 
 public:
 	unsigned precision;
+	bool dsqlLocal;
 };
 
 
@@ -367,7 +369,8 @@ class CurrentTimeStampNode : public TypedNode<ValueExprNode, ExprNode::TYPE_CURR
 public:
 	CurrentTimeStampNode(MemoryPool& pool, unsigned aPrecision)
 		: TypedNode<ValueExprNode, ExprNode::TYPE_CURRENT_TIMESTAMP>(pool),
-		  precision(aPrecision)
+		  precision(aPrecision),
+		  dsqlLocal(false)
 	{
 	}
 
@@ -386,6 +389,7 @@ class CurrentTimeStampNode : public TypedNode<ValueExprNode, ExprNode::TYPE_CURR
 
 public:
 	unsigned precision;
+	bool dsqlLocal;
 };
 
 

src/dsql/parse.y

@@ -589,6 +589,11 @@ using namespace Firebird;
 %token <metaNamePtr> REGR_SXY
 %token <metaNamePtr> REGR_SYY
 
+// tokens added for Firebird 3.0.4
+
+%token <metaNamePtr> LOCALTIME
+%token <metaNamePtr> LOCALTIMESTAMP
+
 // precedence declarations for expression evaluation
 
 %left	OR
@@ -3863,6 +3868,8 @@ keyword_or_column
 	| UPDATING
 	| VAR_SAMP
 	| VAR_POP
+	| LOCALTIME				// added in FB 3.0.4
+	| LOCALTIMESTAMP
 	;
 
 col_opt
@@ -6575,8 +6582,34 @@ datetime_value_expression
 
 			$$ = newNode<CurrentTimeNode>($2);
 		}
+	| LOCALTIME time_precision_opt
+		{
+			if (client_dialect < SQL_DIALECT_V6_TRANSITION)
+			{
+				ERRD_post(Arg::Gds(isc_sqlerr) << Arg::Num(-104) <<
+						  Arg::Gds(isc_sql_dialect_datatype_unsupport) << Arg::Num(client_dialect) <<
+						  												  Arg::Str("TIME"));
+			}
+
+			if (db_dialect < SQL_DIALECT_V6_TRANSITION)
+			{
+				ERRD_post(Arg::Gds(isc_sqlerr) << Arg::Num(-104) <<
+						  Arg::Gds(isc_sql_db_dialect_dtype_unsupport) << Arg::Num(db_dialect) <<
+						  												  Arg::Str("TIME"));
+			}
+
+			CurrentTimeNode* node = newNode<CurrentTimeNode>($2);
+			node->dsqlLocal = true;
+			$$ = node;
+		}
 	| CURRENT_TIMESTAMP timestamp_precision_opt
 		{ $$ = newNode<CurrentTimeStampNode>($2); }
+	| LOCALTIMESTAMP timestamp_precision_opt
+		{
+			CurrentTimeStampNode* node = newNode<CurrentTimeStampNode>($2);
+			node->dsqlLocal = true;
+			$$ = node;
+		}
 	;
 
 %type <uintVal>	time_precision_opt

src/jrd/blp.h

@@ -241,5 +241,10 @@ static const struct
 	{"subfunc", function},
 	{"record_version2", byte_line},
 	{"gen_id2", gen_id2}, // 210
+	{0, 0},
+	{0, 0},
+	{0, 0},
+	{"local_timestamp", byte_line},
+	{"local_time", byte_line},
 	{0, 0}
 };

src/jrd/blr.h

@@ -407,4 +407,9 @@
 #define blr_record_version2			(unsigned char) 209
 #define blr_gen_id2					(unsigned char) 210 // NEXT VALUE FOR generator
 
+// FB 3.0.4 specific BLR
+
+#define blr_local_timestamp         (unsigned char) 214
+#define blr_local_time              (unsigned char) 215
+
 #endif // JRD_BLR_H

src/yvalve/keywords.cpp

@@ -250,6 +250,8 @@ static const TOK tokens[] =
 	{LINGER, "LINGER", 2, true},
 	{LIST, "LIST", 2, false},
 	{LN, "LN", 2, false},
+	{LOCALTIME, "LOCALTIME", 2, true},
+	{LOCALTIMESTAMP, "LOCALTIMESTAMP", 2, true},
 	{LOCK, "LOCK", 2, true},
 	{LOG, "LOG", 2, false},
 	{LOG10, "LOG10", 2, false},