fixes https://github.com/wso2/product-iots/issues/1417

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/config/cache/DeviceCacheConfiguration.java

@@ -26,6 +26,7 @@ public class DeviceCacheConfiguration {
 
     private boolean isEnabled;
     private int expiryTime;
+    private long capacity;
 
     @XmlElement(name = "Enable", required = true)
     public boolean isEnabled() {
@@ -44,4 +45,13 @@ public class DeviceCacheConfiguration {
     public void setExpiryTime(int expiryTime) {
         this.expiryTime = expiryTime;
     }
+
+    @XmlElement(name = "Capacity", required = true)
+    public long getCapacity() {
+        return capacity;
+    }
+
+    public void setCapacity(long capacity) {
+        this.capacity = capacity;
+    }
 }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/util/DeviceManagerUtil.java

@@ -21,6 +21,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.w3c.dom.Document;
 import org.wso2.carbon.base.MultitenantConstants;
+import org.wso2.carbon.caching.impl.CacheImpl;
 import org.wso2.carbon.context.PrivilegedCarbonContext;
 import org.wso2.carbon.device.mgt.analytics.data.publisher.service.EventsPublisherService;
 import org.wso2.carbon.device.mgt.common.Device;
@@ -492,6 +493,7 @@ public final class DeviceManagerUtil {
     public static void initializeDeviceCache() {
         DeviceManagementConfig config = DeviceConfigurationManager.getInstance().getDeviceManagementConfig();
         int deviceCacheExpiry = config.getDeviceCacheConfiguration().getExpiryTime();
+        long deviceCacheCapacity = config.getDeviceCacheConfiguration().getCapacity();
         CacheManager manager = getCacheManager();
         if (config.getDeviceCacheConfiguration().isEnabled()) {
             if(!isDeviceCacheInitialized) {
@@ -502,6 +504,10 @@ public final class DeviceManagerUtil {
                                 setExpiry(CacheConfiguration.ExpiryType.MODIFIED, new CacheConfiguration.Duration(TimeUnit.SECONDS,
                                         deviceCacheExpiry)).setExpiry(CacheConfiguration.ExpiryType.ACCESSED, new CacheConfiguration.
                                 Duration(TimeUnit.SECONDS, deviceCacheExpiry)).setStoreByValue(true).build();
+                        if(deviceCacheCapacity > 0 ) {
+                            ((CacheImpl)(manager.<DeviceCacheKey, Device>getCache(DeviceManagementConstants.DEVICE_CACHE))).
+                                    setCapacity(deviceCacheCapacity);
+                        }
                     } else {
                         manager.<DeviceCacheKey, Device>getCache(DeviceManagementConstants.DEVICE_CACHE);
                     }
@@ -512,6 +518,8 @@ public final class DeviceManagerUtil {
                                 setExpiry(CacheConfiguration.ExpiryType.MODIFIED, new CacheConfiguration.Duration(TimeUnit.SECONDS,
                                         deviceCacheExpiry)).setExpiry(CacheConfiguration.ExpiryType.ACCESSED, new CacheConfiguration.
                                 Duration(TimeUnit.SECONDS, deviceCacheExpiry)).setStoreByValue(true).build();
+                        ((CacheImpl)(manager.<DeviceCacheKey, Device>getCache(DeviceManagementConstants.DEVICE_CACHE))).
+                                setCapacity(deviceCacheCapacity);
                     } else {
                         Caching.getCacheManager().<DeviceCacheKey, Device>getCache(DeviceManagementConstants.DEVICE_CACHE);
                     }

features/device-mgt/org.wso2.carbon.device.mgt.server.feature/src/main/resources/conf/cdm-config.xml

@@ -77,6 +77,7 @@
     <DeviceCacheConfiguration>
         <Enable>true</Enable>
         <ExpiryTime>600</ExpiryTime>
+        <Capacity>10000</Capacity>
     </DeviceCacheConfiguration>
     <CertificateCacheConfiguration>
         <Enable>true</Enable>

features/device-mgt/org.wso2.carbon.device.mgt.server.feature/src/main/resources/dbscripts/cdm/mysql.sql

@@ -9,6 +9,8 @@ CREATE TABLE IF NOT EXISTS DM_DEVICE_TYPE (
 )ENGINE = InnoDB;
 
 CREATE INDEX IDX_DEVICE_TYPE ON DM_DEVICE_TYPE (NAME, PROVIDER_TENANT_ID);
+CREATE INDEX IDX_DEVICE_NAME ON DM_DEVICE_TYPE (NAME);
+CREATE INDEX IDX_DEVICE_TYPE_DEVICE_NAME ON DM_DEVICE_TYPE(ID, NAME);
 
 CREATE TABLE IF NOT EXISTS DM_GROUP (
   ID          INTEGER AUTO_INCREMENT NOT NULL,