diff --git a/services/fulltext_helpers.py b/services/fulltext_helpers.py
new file mode 100644
index 0000000..80d4264
--- /dev/null
+++ b/services/fulltext_helpers.py
@@ -0,0 +1,126 @@
+# Copyright 2016 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 or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""A set of helpers functions for fulltext search."""
+
+from __future__ import division
+from __future__ import print_function
+from __future__ import absolute_import
+
+import logging
+
+from google.appengine.api import search
+
+import settings
+from proto import ast_pb2
+from proto import tracker_pb2
+from search import query2ast
+
+# GAE search API can only respond with 500 results per call.
+_SEARCH_RESULT_CHUNK_SIZE = 500
+
+
+def BuildFTSQuery(query_ast_conj, fulltext_fields):
+  """Convert a Monorail query AST into a GAE search query string.
+
+  Args:
+    query_ast_conj: a Conjunction PB with a list of Comparison PBs that each
+        have operator, field definitions, string values, and int values.
+        All Conditions should be AND'd together.
+    fulltext_fields: a list of string names of fields that may exist in the
+        fulltext documents.  E.g., issue fulltext documents have a "summary"
+        field.
+
+  Returns:
+    A string that can be passed to AppEngine's search API. Or, None if there
+    were no fulltext conditions, so no fulltext search should be done.
+  """
+  fulltext_parts = [
+      _BuildFTSCondition(cond, fulltext_fields)
+      for cond in query_ast_conj.conds]
+  if any(fulltext_parts):
+    return ' '.join(fulltext_parts)
+  else:
+    return None
+
+
+def _BuildFTSCondition(cond, fulltext_fields):
+  """Convert one query AST condition into a GAE search query string."""
+  if cond.op == ast_pb2.QueryOp.NOT_TEXT_HAS:
+    neg = 'NOT '
+  elif cond.op == ast_pb2.QueryOp.TEXT_HAS:
+    neg = ''
+  else:
+    return ''  # FTS only looks at TEXT_HAS and NOT_TEXT_HAS
+
+  parts = []
+
+  for fd in cond.field_defs:
+    if fd.field_name in fulltext_fields:
+      pattern = fd.field_name + ':"%s"'
+    elif fd.field_name == ast_pb2.ANY_FIELD:
+      pattern = '"%s"'
+    elif fd.field_id and fd.field_type == tracker_pb2.FieldTypes.STR_TYPE:
+      pattern = 'custom_' + str(fd.field_id) + ':"%s"'
+    else:
+      pattern = 'pylint does not handle else-continue'
+      continue  # This issue field is searched via SQL.
+
+    for value in cond.str_values:
+      # Strip out quotes around the value.
+      value = value.strip('"')
+      special_prefixes_match = any(
+          value.startswith(p) for p in query2ast.NON_OP_PREFIXES)
+      if not special_prefixes_match:
+        value = value.replace(':', ' ')
+        assert ('"' not in value), 'Value %r has a quote in it' % value
+      parts.append(pattern % value)
+
+  if parts:
+    return neg + '(%s)' % ' OR '.join(parts)
+  else:
+    return ''  # None of the fields were fulltext fields.
+
+
+def ComprehensiveSearch(fulltext_query, index_name):
+  """Call the GAE search API, and keep calling it to get all results.
+
+  Args:
+    fulltext_query: string in the GAE search API query language.
+    index_name: string name of the GAE fulltext index to hit.
+
+  Returns:
+    A list of integer issue IIDs or project IDs.
+  """
+  search_index = search.Index(name=index_name)
+
+  try:
+    response = search_index.search(search.Query(
+        fulltext_query,
+        options=search.QueryOptions(
+            limit=_SEARCH_RESULT_CHUNK_SIZE, returned_fields=[], ids_only=True,
+            cursor=search.Cursor())))
+  except ValueError as e:
+    raise query2ast.InvalidQueryError(e.message)
+
+  logging.info('got %d initial results', len(response.results))
+  ids = [int(result.doc_id) for result in response]
+
+  remaining_iterations = int(
+      (settings.fulltext_limit_per_shard - 1) // _SEARCH_RESULT_CHUNK_SIZE)
+  for _ in range(remaining_iterations):
+    if not response.cursor:
+      break
+    response = search_index.search(search.Query(
+        fulltext_query,
+        options=search.QueryOptions(
+            limit=_SEARCH_RESULT_CHUNK_SIZE, returned_fields=[], ids_only=True,
+            cursor=response.cursor)))
+    logging.info(
+        'got %d more results: %r', len(response.results), response.results)
+    ids.extend(int(result.doc_id) for result in response)
+
+  logging.info('FTS result ids %d', len(ids))
+  return ids