Add facility to report data size in bytes of SQL query

Author: developernotes

android-database-sqlcipher/src/main/java/net/sqlcipher/database/SQLiteDatabase.java

@@ -25,6 +25,7 @@
 import net.sqlcipher.SQLException;
 import net.sqlcipher.database.SQLiteDebug.DbStats;
 import net.sqlcipher.database.SQLiteDatabaseHook;
+import net.sqlcipher.database.SQLiteQueryStats;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -1842,6 +1843,38 @@ public Cursor rawQuery(String sql, String[] selectionArgs) {
         return rawQueryWithFactory(null, sql, selectionArgs, null);
     }
 
+  /**
+   * Determines the total size in bytes of the query results, and the largest
+   * single row in bytes for the query.
+   *
+   * @param sql the SQL query. The SQL string must a SELECT statement
+   * @param args the argments to bind to the query
+   *
+   * @return A {@link SQLiteQueryStats} based the provided SQL query.
+   */
+  public SQLiteQueryStats getQueryStats(String sql, Object[] args){
+    long totalPayload = 0L;
+    long largestIndividualPayload = 0L;
+    try {
+      String query = String.format("CREATE TABLE tempstat AS %s", sql);
+      execSQL(query, args);
+      Cursor cursor = rawQuery("SELECT sum(payload) FROM dbstat WHERE name = 'tempstat';", new Object[]{});
+      if(cursor == null) return new SQLiteQueryStats(totalPayload, largestIndividualPayload);
+      cursor.moveToFirst();
+      totalPayload = cursor.getLong(0);
+      cursor.close();
+      cursor = rawQuery("SELECT max(mx_payload) FROM dbstat WHERE name = 'tempstat';", new Object[]{});
+      if(cursor == null) return new SQLiteQueryStats(totalPayload, largestIndividualPayload);
+      cursor.moveToFirst();
+      largestIndividualPayload = cursor.getLong(0);
+      cursor.close();
+      execSQL("DROP TABLE tempstat;");
+    } catch(Exception ex) {
+      execSQL("DROP TABLE IF EXISTS tempstat;");
+      throw ex;
+    }
+    return new SQLiteQueryStats(totalPayload, largestIndividualPayload);
+  }
 
       /**
      * Runs the provided SQL and returns a {@link Cursor} over the result set.

android-database-sqlcipher/src/main/java/net/sqlcipher/database/SQLiteQueryStats.java

@@ -0,0 +1,20 @@
+package net.sqlcipher.database;
+
+public class SQLiteQueryStats {
+  long totalQueryResultSize = 0L;
+  long largestIndividualRowSize = 0L;
+
+  public SQLiteQueryStats(long totalQueryResultSize,
+                          long largestIndividualRowSize) {
+    this.totalQueryResultSize = totalQueryResultSize;
+    this.largestIndividualRowSize = largestIndividualRowSize;
+  }
+
+  public long getTotalQueryResultSize(){
+    return totalQueryResultSize;
+  }
+
+  public long getLargestIndividualRowSize(){
+    return largestIndividualRowSize;
+  }
+}

build.gradle

@@ -76,7 +76,8 @@ ext {
     "-DSQLITE_ENABLE_FTS3_PARENTHESIS " +
     "-DSQLITE_ENABLE_FTS4 " +
     "-DSQLITE_ENABLE_FTS5 " +
-    "-DSQLCIPHER_CRYPTO_OPENSSL"
+    "-DSQLCIPHER_CRYPTO_OPENSSL " +
+    "-DSQLITE_ENABLE_DBSTAT_VTAB"
 }
 
 task clean(type: Delete) {