diff -ruBN barnyard-0.2.0/src/output-plugins/op_acid_db.c barnyard-0.2.0-caching/src/output-plugins/op_acid_db.c
--- barnyard-0.2.0/src/output-plugins/op_acid_db.c	2004-04-03 13:57:32.000000000 -0600
+++ barnyard-0.2.0-caching/src/output-plugins/op_acid_db.c	2006-04-07 23:35:40.000000000 -0500
@@ -45,6 +45,14 @@
 #endif /* ENABLE_POSTGRES */
 
 /*  D A T A   S T R U C T U R E S  **************************************/
+typedef struct _DbSignature
+{
+    int gen;
+    int sid;
+    int sig_id;
+    struct DbSignature *next;
+} DbSignature;
+
 typedef struct _OpAcidDb_Data 
 {
     u_int8_t flavor;  /* what flavor of db?  MySQL, postgres, ... */
@@ -57,6 +65,7 @@
     int sensor_id;
     u_int32_t event_id;
     int linktype;
+    DbSignature *sig_cache;
     /* db handles go here */
 #ifdef ENABLE_MYSQL
     MYSQL *mysql;
@@ -105,6 +113,11 @@
 int Insert(OpAcidDb_Data *data, char *sql, unsigned int *row_id);
 char *EscapeString(OpAcidDb_Data *data, char *string);
 
+DbSignature * AddDbSignature (DbSignature *dbsig, u_int32_t gen, u_int32_t sid, u_int32_t sig_id);
+DbSignature * RemoveDbSignature (DbSignature *dbsig);
+int FindDbSignature (DbSignature *dbsig, u_int32_t gen, u_int32_t sid, u_int32_t *sig_id);
+void ClearDbSignatures (DbSignature *dbsig);
+
 #ifdef ENABLE_MYSQL
 int MysqlConnect(OpAcidDb_Data *);
 int MysqlClose(MYSQL *mysql);
@@ -195,6 +208,8 @@
     if(data == NULL)
         FatalError("ERROR: Unable to find context for AcidDb startup!\n");
     
+    data->sig_cache = NULL;
+
     if(pv.verbose)
     {
         OpAcidDb_LogConfig(outputPlugin);
@@ -729,7 +744,7 @@
  * Returns 1 on success
  */
 static int OpAcidDb_GetSigId(OpAcidDb_Data *op_data, char *msg, u_int32_t rev,
-        u_int32_t sid, u_int32_t *sig_id)
+        u_int32_t sid, u_int32_t gen, u_int32_t *sig_id)
 {
     int rval;
     char *e_message = NULL;
@@ -737,6 +752,11 @@
     if(!msg)
         msg = "";
 
+    if(FindDbSignature(op_data->sig_cache, gen, sid, sig_id))
+    {
+      return 1;
+    }
+
     if(!(e_message = EscapeString(op_data, msg)))
         FatalError("Failed to escape string");
 
@@ -745,6 +765,10 @@
             "AND sig_sid=%u", e_message, rev, sid) < MAX_QUERY_SIZE)
     {
         rval = SelectAsUInt(op_data, sql_buffer, sig_id);
+        if(*sig_id != 0)
+        {
+            op_data->sig_cache = AddDbSignature(op_data->sig_cache, gen, sid, *sig_id);
+        }
         free(e_message);
         return rval;
     }
@@ -839,7 +863,7 @@
     if(!sid)
         return 0;
     
-    if(OpAcidDb_GetSigId(op_data, sid->msg, sid->rev, sid->sid, &sig_id) == 1)
+    if(OpAcidDb_GetSigId(op_data, sid->msg, sid->rev, sid->sid, sid->gen, &sig_id) == 1)
         return sig_id;
     
     /* Create a new signature entry */
@@ -857,7 +881,11 @@
         free(e_message);
         if(sig_id == -1)
         {
-            OpAcidDb_GetSigId(op_data, sid->msg, sid->rev, sid->sid, &sig_id);
+            OpAcidDb_GetSigId(op_data, sid->msg, sid->rev, sid->sid, sid->gen, &sig_id);
+        }
+        else
+        {
+            op_data->sig_cache = AddDbSignature(op_data->sig_cache, sid->gen, sid->sid, sig_id);
         }
     }
     else
@@ -1196,6 +1224,78 @@
     }
 }
         
+DbSignature * AddDbSignature (DbSignature *dbsig, u_int32_t gen, u_int32_t sid, u_int32_t sig_id)
+{
+
+    if(dbsig != NULL)
+    {
+        DbSignature *sig = dbsig;
+        while(dbsig->next != NULL)
+        {
+            dbsig = (DbSignature *)dbsig->next;
+        }
+        dbsig->next = (DbSignature *)SafeAlloc(sizeof(DbSignature));
+        dbsig = (DbSignature *)dbsig->next;
+        dbsig->next = NULL;
+        dbsig->gen = gen;
+        dbsig->sid = sid;
+        dbsig->sig_id = sig_id;
+        return sig;
+    }
+    else
+    {
+        dbsig = (DbSignature *)SafeAlloc(sizeof(DbSignature));
+        dbsig->next = NULL;
+        dbsig->gen = gen;
+        dbsig->sid = sid;
+        dbsig->sig_id = sig_id;
+        return dbsig;
+    }
+
+}
+
+DbSignature * RemoveDbSignature (DbSignature *dbsig)
+{
+
+    DbSignature *sig = (DbSignature *)dbsig->next;
+    free(dbsig);
+    return sig;
+
+}
+
+int FindDbSignature (DbSignature *dbsig, u_int32_t gen, u_int32_t sid, u_int32_t *sig_id)
+{
+
+    if(dbsig == NULL)
+    {
+        return 0;
+    }
+
+    while(dbsig != NULL)
+    {
+        if(dbsig->gen == gen && dbsig->sid == sid) {
+            *sig_id = dbsig->sig_id;
+            return 1;
+        }
+        dbsig = (DbSignature *)dbsig->next;
+    }
+
+    return 0;
+
+}
+
+void ClearDbSignatures (DbSignature *dbsig)
+{
+
+    if(dbsig != NULL)
+    {
+        while(dbsig != NULL)
+        {
+            dbsig = RemoveDbSignature(dbsig);
+        }
+    }
+
+}
 
 #ifdef ENABLE_MYSQL
 int MysqlConnect(OpAcidDb_Data *op_data)