Revert "Merge pull request #7982 from jketema/remove-legacy-relations"

This reverts commit 2b6d57d, reversing
changes made to 9b4dbb9.

Author: MathiasVP

cpp/downgrades/7455933b9d8832b7c385cfca8cf43bddc25b6d0f/old.dbscheme

@@ -4,16 +4,12 @@
 
 import cpp
 
-private newtype TExternalDataElement = MKExternalDataElement()
-
 /**
- * DEPRECATED: This class is no longer used.
- *
  * An external data item.
  */
-class ExternalData extends TExternalDataElement {
+class ExternalData extends @externalDataElement {
   /** Gets the path of the file this data was loaded from. */
-  string getDataPath() { none() }
+  string getDataPath() { externalData(this, result, _, _) }
 
   /**
    * Gets the path of the file this data was loaded from, with its
@@ -22,10 +18,10 @@ class ExternalData extends TExternalDataElement {
   string getQueryPath() { result = this.getDataPath().regexpReplaceAll("\\.[^.]*$", ".ql") }
 
   /** Gets the number of fields in this data item. */
-  int getNumFields() { none() }
+  int getNumFields() { result = 1 + max(int i | externalData(this, _, i, _) | i) }
 
   /** Gets the value of the `i`th field of this data item. */
-  string getField(int i) { none() }
+  string getField(int i) { externalData(this, _, i, result) }
 
   /** Gets the integer value of the `i`th field of this data item. */
   int getFieldAsInt(int i) { result = this.getField(i).toInt() }

cpp/downgrades/7455933b9d8832b7c385cfca8cf43bddc25b6d0f/semmlecode.cpp.dbscheme

@@ -122,11 +122,65 @@ compilation_finished(
     float elapsed_seconds : float ref
 );
 
+
+/**
+ * External data, loaded from CSV files during snapshot creation. See
+ * [Tutorial: Incorporating external data](https://help.semmle.com/wiki/display/SD/Tutorial%3A+Incorporating+external+data)
+ * for more information.
+ */
+externalData(
+    int id : @externalDataElement,
+    string path : string ref,
+    int column: int ref,
+    string value : string ref
+);
+
+/**
+ * The date of the snapshot.
+ */
+snapshotDate(unique date snapshotDate : date ref);
+
 /**
  * The source location of the snapshot.
  */
 sourceLocationPrefix(string prefix : string ref);
 
+/**
+ * Data used by the 'duplicate code' detection.
+ */
+duplicateCode(
+    unique int id : @duplication,
+    string relativePath : string ref,
+    int equivClass : int ref
+);
+
+/**
+ * Data used by the 'similar code' detection.
+ */
+similarCode(
+    unique int id : @similarity,
+    string relativePath : string ref,
+    int equivClass : int ref
+);
+
+/**
+ * Data used by the 'duplicate code' and 'similar code' detection.
+ */
+@duplication_or_similarity = @duplication | @similarity
+
+/**
+ * Data used by the 'duplicate code' and 'similar code' detection.
+ */
+#keyset[id, offset]
+tokens(
+    int id : @duplication_or_similarity ref,
+    int offset : int ref,
+    int beginLine : int ref,
+    int beginColumn : int ref,
+    int endLine : int ref,
+    int endColumn : int ref
+);
+
 /**
  * Information about packages that provide code used during compilation.
  * The `id` is just a unique identifier.