support for read replicas with postgres

reporting/BackendInterface.h

@@ -132,7 +132,7 @@ public:
     // Open the database. Set up all of the necessary objects and
     // datastructures. After this call completes, the database is ready for use.
     virtual void
-    open() = 0;
+    open(bool readOnly) = 0;
 
     // Close the database, releasing any resources
     virtual void

reporting/CassandraBackend.cpp

@@ -273,7 +273,7 @@ CassandraBackend::doOnlineDelete(uint32_t minLedgerToKeep) const
 }
 
 void
-CassandraBackend::open()
+CassandraBackend::open(bool readOnly)
 {
     std::cout << config_ << std::endl;
     auto getString = [this](std::string const& field) -> std::string {

reporting/CassandraBackend.h

@@ -665,7 +665,7 @@ public:
     // Create the table if it doesn't exist already
     // @param createIfMissing ignored
     void
-    open() override;
+    open(bool readOnly) override;
 
     // Close the connection to the database
     void

reporting/PostgresBackend.cpp

@@ -625,9 +625,10 @@ PostgresBackend::fetchAccountTransactions(
 }  // namespace Backend
 
 void
-PostgresBackend::open()
+PostgresBackend::open(bool readOnly)
 {
-    initSchema(pgPool_);
+    if (!readOnly)
+        initSchema(pgPool_);
 }
 
 void

reporting/PostgresBackend.h

@@ -101,7 +101,7 @@ public:
         std::vector<AccountTransactionsData>&& data) const override;
 
     void
-    open() override;
+    open(bool readOnly) override;
 
     void
     close() override;

reporting/ReportingETL.cpp

@@ -711,7 +711,6 @@ ReportingETL::ReportingETL(
           networkValidatedLedgers_,
           ioc)
 {
-    flatMapBackend_->open();
     if (config.contains("start_sequence"))
         startSequence_ = config.at("start_sequence").as_int64();
     if (config.contains("finish_sequence"))
@@ -724,5 +723,6 @@ ReportingETL::ReportingETL(
         extractorThreads_ = config.at("extractor_threads").as_int64();
     if (config.contains("txn_threshold"))
         txnThreshold_ = config.at("txn_threshold").as_int64();
+    flatMapBackend_->open(readOnly_);
 }