[sql] Use IGNORE conflict resolution in recovery.

sql/recovery.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sql/recovery.h"
 
 #include <stddef.h>
 
 #include "base/files/file_path.h"
 #include "base/format_macros.h"
@@ skipping 357 matching lines @@
   // seen.  |pk_column_count| counts the columns in the primary key.
   // |rowid_decl| stores the ROWID version of the last INTEGER column
   // seen, which is at |rowid_ofs| in |create_column_decls|.
   size_t pk_column_count = 0;
   size_t rowid_ofs = 0;  // Only valid if rowid_decl is set.
   std::string rowid_decl;  // ROWID version of column |rowid_ofs|.
 
   while (s.Step()) {
     const std::string column_name(s.ColumnString(1));
     const std::string column_type(s.ColumnString(2));
-    const bool not_null = s.ColumnBool(3);
     const int default_type = s.ColumnType(4);
     const bool default_is_null = (default_type == COLUMN_TYPE_NULL);
     const int pk_column = s.ColumnInt(5);
 
     // http://www.sqlite.org/pragma.html#pragma_table_info documents column 5 as
     // the 1-based index of the column in the primary key, otherwise 0.
     if (pk_column > 0)
       ++pk_column_count;
 
     // Construct column declaration as "name type [optional constraint]".
@@ skipping 26 matching lines @@
       // - contains("CLOB") -> TEXT
       // - contains("REAL") -> FLOAT
       // - contains("FLOA") -> FLOAT
       // - other -> "NUMERIC"
       // Just code those in as they come up.
       NOTREACHED() << " Unsupported type " << column_type;
       RecordRecoveryEvent(RECOVERY_FAILED_AUTORECOVER_UNRECOGNIZED_TYPE);
       return false;
     }
 
-    // If column has constraint "NOT NULL", then inserting NULL into
-    // that column will fail.  If the column has a non-NULL DEFAULT
-    // specified, the INSERT will handle it (see below).  If the
-    // DEFAULT is also NULL, the row must be filtered out.
-    // TODO(shess): The above scenario applies to INSERT OR REPLACE,
-    // whereas INSERT OR IGNORE drops such rows.
-    // http://www.sqlite.org/lang_conflict.html

[Ryan Hamilton, 2016/02/04 01:38:17]

Looks like you planned ahead! Nice comment.

-    if (not_null && default_is_null)
-      column_decl += " NOT NULL";
-
     create_column_decls.push_back(column_decl);
 
     // Per the NOTE in the header file, convert NULL values to the
     // DEFAULT.  All columns could be IFNULL(column_name,default), but
     // the NULL case would require special handling either way.
     if (default_is_null) {
       insert_columns.push_back(column_name);
     } else {
       // The default value appears to be pre-quoted, as if it is
       // literally from the sqlite_master CREATE statement.
@@ skipping 12 matching lines @@
   // If the PRIMARY KEY was a single INTEGER column, convert it to ROWID.
   if (pk_column_count == 1 && !rowid_decl.empty())
     create_column_decls[rowid_ofs] = rowid_decl;
 
   std::string recover_create(base::StringPrintf(
       "CREATE VIRTUAL TABLE temp.recover_%s USING recover(corrupt.%s, %s)",
       table_name,
       table_name,
       base::JoinString(create_column_decls, ",").c_str()));
 
+  // INSERT OR IGNORE means that it will drop rows resulting from constraint
+  // violations.  INSERT OR REPLACE only handles UNIQUE constraint violations.
   std::string recover_insert(base::StringPrintf(
-      "INSERT OR REPLACE INTO main.%s SELECT %s FROM temp.recover_%s",
+      "INSERT OR IGNORE INTO main.%s SELECT %s FROM temp.recover_%s",
       table_name,
       base::JoinString(insert_columns, ",").c_str(),
       table_name));
 
   std::string recover_drop(base::StringPrintf(
       "DROP TABLE temp.recover_%s", table_name));
 
   if (!db()->Execute(recover_create.c_str())) {
     RecordRecoveryEvent(RECOVERY_FAILED_AUTORECOVER_CREATE);
     return false;
@@ skipping 49 matching lines @@
     }
     return false;
   }
 
   RecordRecoveryEvent(RECOVERY_SUCCESS_META_VERSION);
   *version = recovery_version.ColumnInt(0);
   return true;
 }
 
 }  // namespace sql