Optimize data fetching

src/main/java/org/jabref/logic/shared/DBMSProcessor.java

@@ -431,6 +431,54 @@ public List<BibEntry> getSharedEntries() {
         return getSharedEntryList(0);
     }
 
+    public List<BibEntry> getSharedEntriesByIdList(List<Integer> idList) {
+        List<BibEntry> sharedEntries = new ArrayList<>();
+
+        StringBuilder query = new StringBuilder();
+        query.append("SELECT ")
+                .append(escape("ENTRY") + "." + escape("SHARED_ID")).append(", ")
+                .append(escape("ENTRY") + "." + escape("TYPE")).append(", ")
+                .append(escape("ENTRY") + "." + escape("VERSION")).append(", ")
+                .append("F." + escape("ENTRY_SHARED_ID")).append(", ")
+                .append("F." + escape("NAME")).append(", ")
+                .append("F." + escape("VALUE"))
+                .append(" FROM ")
+                .append(escape("ENTRY"))
+                .append(" inner join ")
+                .append(escape("FIELD"))
+                .append(" F on ")
+                .append(escape("ENTRY") + ".")
+                .append(escape("SHARED_ID") + " = F." + escape("ENTRY_SHARED_ID"))
+                .append(" where ")
+                .append(escape("SHARED_ID")).append(" in (");
+
+        for (int i = 0; i < idList.size() - 1; i++) {
+            query.append(idList.get(i)).append(", ");
+        }
+        query.append(idList.get(idList.size() - 1)).append(") order by ").append(escape("SHARED_ID")).append(";");
+
+        try (ResultSet selectEntryResultSet = connection.createStatement().executeQuery(query.toString())) {
+            BibEntry bibEntry = null;
+            int lastId = -1;
+            while (selectEntryResultSet.next()) {
+                if (selectEntryResultSet.getInt("SHARED_ID") > lastId) {
+                    bibEntry = new BibEntry();
+                    bibEntry.getSharedBibEntryData().setSharedID(selectEntryResultSet.getInt("SHARED_ID"));
+                    bibEntry.setType(selectEntryResultSet.getString("TYPE"));
+                    bibEntry.getSharedBibEntryData().setVersion(selectEntryResultSet.getInt("VERSION"));
+                    sharedEntries.add(bibEntry);
+                    lastId = selectEntryResultSet.getInt("SHARED_ID");
+                }
+
+                bibEntry.setField(selectEntryResultSet.getString("NAME"), Optional.ofNullable(selectEntryResultSet.getString("VALUE")), EntryEventSource.SHARED);
+            }
+        } catch (SQLException e) {
+            LOGGER.error("SQL Error", e);
+        }
+
+        return sharedEntries;
+    }
+
     /**
      * @param sharedID Entry ID. If 0, all entries are going to be fetched.
      * @return List of {@link BibEntry} instances

src/main/java/org/jabref/logic/shared/DBMSSynchronizer.java

@@ -2,6 +2,7 @@
 
 import java.sql.Connection;
 import java.sql.SQLException;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -175,7 +176,7 @@ public void synchronizeLocalDatabase() {
 
         // remove old entries locally
         removeNotSharedEntries(localEntries, idVersionMap.keySet());
-
+        List<Integer> entryToDrag = new ArrayList<>();
         // compare versions and update local entry if needed
         for (Map.Entry<Integer, Integer> idVersionEntry : idVersionMap.entrySet()) {
             boolean match = false;
@@ -205,12 +206,13 @@ public void synchronizeLocalDatabase() {
                 }
             }
             if (!match) {
-                Optional<BibEntry> bibEntry = dbmsProcessor.getSharedEntry(idVersionEntry.getKey());
-                if (bibEntry.isPresent()) {
-                    bibDatabase.insertEntry(bibEntry.get(), EntryEventSource.SHARED);
-                }
+                entryToDrag.add(idVersionEntry.getKey());
             }
         }
+
+        for (BibEntry bibEntry : dbmsProcessor.getSharedEntriesByIdList(entryToDrag)) {
+            bibDatabase.insertEntry(bibEntry, EntryEventSource.SHARED);
+        }
     }
 
     /**
@@ -322,10 +324,10 @@ public void pullChanges() {
     }
 
     /**
-     *  Checks whether the current SQL connection is valid.
-     *  In case that the connection is not valid a new {@link ConnectionLostEvent} is going to be sent.
+     *Checks whether the current SQL connection is valid.
+     *In case that the connection is not valid a new {@link ConnectionLostEvent} is going to be sent.
      *
-     *  @return <code>true</code> if the connection is valid, else <code>false</code>.
+     *@return <code>true</code> if the connection is valid, else <code>false</code>.
      */
     public boolean checkCurrentConnection() {
         try {