FirebirdSQL · asfernandes · Mar 13, 2026
diff --git a/src/dsql/DdlNodes.epp b/src/dsql/DdlNodes.epp
@@ -99,6 +99,7 @@ static const UCHAR nonnull_validation_blr[] =
 	blr_eoc
 };
 
+static void checkDeferredDdlInReadOnlyReplica(thread_db* tdbb);
 static void checkForeignKeyTempScope(thread_db* tdbb, jrd_tra* transaction,
 	const QualifiedName&	childRelName, const QualifiedName& masterIndexName);
 static void checkLttNotInUse(thread_db* tdbb, jrd_tra* transaction, const LocalTemporaryTable* ltt);
@@ -209,6 +210,16 @@ void ExecInSecurityDb::executeInSecurityDb(jrd_tra* localTransaction)
 //----------------------
 
 
+// Check if we are trying to execute prohibited DDL in read-only replica and raise an error if so.
+static void checkDeferredDdlInReadOnlyReplica(thread_db* tdbb)
+{
+	if (tdbb->getDatabase()->isReplica(REPLICA_READ_ONLY) &&
+		!(tdbb->tdbb_flags & TDBB_replicator))
+	{
+		ERRD_post(Arg::Gds(isc_read_only_trans));
+	}
+}
+
 // Check temporary table reference rules between given child relation and master
 // relation (owner of given PK/UK index).
 static void checkForeignKeyTempScope(thread_db* tdbb, jrd_tra* transaction,
@@ -9233,6 +9244,7 @@ void CreateRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScrat
 
 	if (tempFlag == REL_temp_ltt)
 	{
+		dsqlScratch->flags |= DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
 		defineLocalTempTable(tdbb, dsqlScratch, transaction);
 
 		dsqlScratch->relation->rel_flags &= ~REL_creating;
@@ -9619,6 +9631,7 @@ void AlterRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratc
 	// Handle Local Temporary Tables differently
 	if (relation->rel_flags & REL_ltt_created)
 	{
+		dsqlScratch->flags |= DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
 		alterLocalTempTable(tdbb, dsqlScratch, transaction);
 
 		// Update DSQL cache
@@ -9627,6 +9640,8 @@ void AlterRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratc
 		return;
 	}
 
+	checkDeferredDdlInReadOnlyReplica(tdbb);
+
 	bool beforeTriggerWasExecuted = false;
 
 	const auto executeBeforeTrigger = [&]()
@@ -10940,6 +10955,8 @@ void DropRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch
 
 	if (const auto lttIt = attachment->att_local_temporary_tables.get(name))
 	{
+		dsqlScratch->flags |= DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
+
 		if (view)
 		{
 			status_exception::raise(
@@ -10977,6 +10994,8 @@ void DropRelationNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch
 	if (!rel && silent)
 		return;
 
+	checkDeferredDdlInReadOnlyReplica(tdbb);
+
 	if (tdbb->getDatabase()->readOnly())
 		ERRD_post(Arg::Gds(isc_read_only_database));
 
@@ -13197,11 +13216,14 @@ void CreateIndexNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch,
 	// Check if target relation is a Local Temporary Table
 	if (const auto lttPtr = attachment->att_local_temporary_tables.get(relation->dsqlName))
 	{
+		dsqlScratch->flags |= DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
 		defineLocalTempIndex(tdbb, dsqlScratch, transaction, *lttPtr);
 		savePoint.release();	// everything is ok
 		return;
 	}
 
+	checkDeferredDdlInReadOnlyReplica(tdbb);
+
 	if (tdbb->getDatabase()->readOnly())
 		ERRD_post(Arg::Gds(isc_read_only_database));
 
@@ -13430,11 +13452,14 @@ void AlterIndexNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch,
 
 	if (MET_get_ltt_index(transaction->getAttachment(), indexName, &ltt, &lttIndex))
 	{
+		dsqlScratch->flags |= DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
 		alterLocalTempIndex(tdbb, dsqlScratch, transaction, ltt, lttIndex);
 		savePoint.release();	// everything is ok
 		return;
 	}
 
+	checkDeferredDdlInReadOnlyReplica(tdbb);
+
 	if (tdbb->getDatabase()->readOnly())
 		ERRD_post(Arg::Gds(isc_read_only_database));
 
@@ -13629,11 +13654,14 @@ void SetStatisticsNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratc
 
 	if (MET_get_ltt_index(transaction->getAttachment(), indexName, &ltt, &lttIndex))
 	{
+		dsqlScratch->flags |= DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
 		setStatisticsLocalTempIndex(tdbb, dsqlScratch, transaction, ltt, lttIndex);
 		savePoint.release();	// everything is ok
 		return;
 	}
 
+	checkDeferredDdlInReadOnlyReplica(tdbb);
+
 	AutoCacheRequest request(tdbb, drq_m_set_statistics, DYN_REQUESTS);
 	bool found = false;
 
@@ -13744,11 +13772,14 @@ void DropIndexNode::execute(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch, j
 
 	if (MET_get_ltt_index(transaction->getAttachment(), indexName, &ltt, &lttIndex))
 	{
+		dsqlScratch->flags |= DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
 		dropLocalTempIndex(tdbb, dsqlScratch, transaction, ltt, lttIndex);
 		savePoint.release();	// everything is ok
 		return;
 	}
 
+	checkDeferredDdlInReadOnlyReplica(tdbb);
+
 	if (tdbb->getDatabase()->readOnly())
 		ERRD_post(Arg::Gds(isc_read_only_database));
 

diff --git a/src/dsql/DdlNodes.h b/src/dsql/DdlNodes.h
@@ -237,6 +237,11 @@ class RecreateNode : public DdlNode
 		return createNode->disallowedInReadOnlyDatabase();
 	}
 
+	bool mustBeReplicated() const override
+	{
+		return createNode->mustBeReplicated();
+	}
+
 protected:
 	void putErrorPrefix(Firebird::Arg::StatusVector& statusVector) override
 	{
@@ -1760,6 +1765,11 @@ class CreateRelationNode final : public RelationNode
 		return RelationNode::dsqlPass(dsqlScratch);
 	}
 
+	bool mustBeReplicated() const override
+	{
+		return tempFlag != REL_temp_ltt;
+	}
+
 	bool disallowedInReadOnlyDatabase() const override
 	{
 		return tempFlag != REL_temp_ltt;
@@ -2128,6 +2138,11 @@ class SetStatisticsNode final : public DdlNode
 		return DdlNode::dsqlPass(dsqlScratch);
 	}
 
+	bool disallowedInReadOnlyDatabase() const override
+	{
+		return false;  // Deferred to execute() - LTT status unknown at parse time
+	}
+
 private:
 	void setStatisticsLocalTempIndex(thread_db* tdbb, DsqlCompilerScratch* dsqlScratch,
 		jrd_tra* transaction, LocalTemporaryTable* ltt, LocalTemporaryTable::Index* lttIndex);

diff --git a/src/dsql/DsqlCompilerScratch.h b/src/dsql/DsqlCompilerScratch.h
@@ -78,6 +78,7 @@ class DsqlCompilerScratch : public BlrDebugWriter
 	static const unsigned FLAG_EXEC_BLOCK			= 0x010000;
 	static const unsigned FLAG_ALLOW_LTT_REFERENCES	= 0x020000;
 	static const unsigned FLAG_USING_STATEMENT		= 0x040000;
+	static const unsigned FLAG_ACTUAL_LTT_DDL		= 0x080000;
 
 	static const unsigned MAX_NESTING = 512;
 

diff --git a/src/dsql/DsqlRequests.cpp b/src/dsql/DsqlRequests.cpp
@@ -972,6 +972,7 @@ void DsqlDdlRequest::execute(thread_db* tdbb, jrd_tra** traHandle,
 		try
 		{
 			AutoSetRestoreFlag<ULONG> execDdl(&tdbb->tdbb_flags, TDBB_repl_in_progress, true);
+			internalScratch->flags &= ~DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL;
 
 			//// Doing it in DFW_perform_work to avoid problems with DDL+DML in the same transaction.
 			/// req_dbb->dbb_attachment->att_dsql_instance->dbb_statement_cache->purgeAllAttachments(tdbb);
@@ -981,7 +982,9 @@ void DsqlDdlRequest::execute(thread_db* tdbb, jrd_tra** traHandle,
 			const bool isInternalRequest =
 				(internalScratch->flags & DsqlCompilerScratch::FLAG_INTERNAL_REQUEST);
 
-			if (!isInternalRequest && node->mustBeReplicated())
+			if (!isInternalRequest &&
+				node->mustBeReplicated() &&
+				!(internalScratch->flags & DsqlCompilerScratch::FLAG_ACTUAL_LTT_DDL))
 			{
 				REPL_exec_sql(tdbb, req_transaction, getDsqlStatement()->getOrgText(),
 					*getDsqlStatement()->getSchemaSearchPath());

diff --git a/src/dsql/DsqlStatements.cpp b/src/dsql/DsqlStatements.cpp
@@ -261,7 +261,8 @@ void DsqlDdlStatement::dsqlPass(thread_db* tdbb, DsqlCompilerScratch* scratch, n
 	// As an exception, not replicated DDL statements are also allowed.
 	if (dbb->isReplica(REPLICA_READ_ONLY) &&
 		!(tdbb->tdbb_flags & TDBB_replicator) &&
-		node->mustBeReplicated())
+		node->mustBeReplicated() &&
+		node->disallowedInReadOnlyDatabase())
 	{
 		ERRD_post(Arg::Gds(isc_read_only_trans));
 	}