diff --git a/build.gradle b/build.gradle
index 6063a7ed8..c506fb99f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -191,7 +191,7 @@ allprojects {
 }
 
 task runPresubmits(type: Exec) {
-  executable '/usr/bin/python'
+  executable '/usr/bin/python3'
   args('config/presubmits.py')
 }
 
diff --git a/config/presubmits.py b/config/presubmits.py
index 3d827aaba..44fb511f4 100644
--- a/config/presubmits.py
+++ b/config/presubmits.py
@@ -18,6 +18,7 @@ Error Prone) so we must write them manually.
 """
 
 import os
+from typing import List, Tuple
 import sys
 import re
 
@@ -178,6 +179,90 @@ PRESUBMITS = {
         "JavaScript files should not include console logging."
 }
 
+# Note that this regex only works for one kind of Flyway file.  If we want to
+# start using "R" and "U" files we'll need to update this script.
+FLYWAY_FILE_RX = re.compile(r'V(\d+)__.*')
+
+
+def get_seqnum(filename: str, location: str) -> int:
+  """Extracts the sequence number from a filename."""
+  m = FLYWAY_FILE_RX.match(filename)
+  if m is None:
+    raise ValueError('Illegal Flyway filename: %s in %s' % (filename, location))
+  return int(m.group(1))
+
+
+def files_by_seqnum(files: List[str], location: str) -> List[Tuple[int, str]]:
+  """Returns the list of seqnum, filename sorted by sequence number."""
+  return [(get_seqnum(filename, location), filename) for filename in files]
+
+
+def has_valid_order(indexed_files: List[Tuple[int, str]], location: str) -> bool:
+  """Verify that sequence numbers are in order without gaps or duplicates.
+
+  Args:
+    files: List of seqnum, filename for a list of Flyway files.
+    location: Where the list of files came from (for error reporting).
+
+  Returns:
+    True if the file list is valid.
+  """
+  last_index = 0
+  valid = True
+  for seqnum, filename in indexed_files:
+    if seqnum == last_index:
+      print('duplicate Flyway file sequence number found in %s: %s' %
+            (location, filename))
+      valid = False
+    elif seqnum < last_index:
+      print('File %s in %s is out of order.' % (filename, location))
+      valid = False
+    elif seqnum != last_index + 1:
+      print('Missing Flyway sequence number %d in %s.  Next file is %s' %
+            (last_index + 1, location, filename))
+      valid = False
+    last_index = seqnum
+  return valid
+
+
+def verify_flyway_index():
+  """Verifies that the Flyway index file is in sync with the directory."""
+  success = True
+
+  # Sort the files in the Flyway directory by their sequence number.
+  files = sorted(
+      files_by_seqnum(os.listdir('db/src/main/resources/sql/flyway'),
+                      'Flyway directory'))
+
+  # Make sure that there are no gaps and no duplicate sequence numbers in the
+  # files themselves.
+  if not has_valid_order(files, 'Flyway directory'):
+    success = False
+
+  # Remove the sequence numbers and compare against the index file contents.
+  files = [filename[1] for filename in sorted(files)]
+  with open('db/src/main/resources/sql/flyway.txt') as index:
+    indexed_files = index.read().splitlines()
+  if files != indexed_files:
+    unindexed = set(files) - set(indexed_files)
+    if unindexed:
+      print('The following Flyway files are not in flyway.txt: %s' % unindexed)
+
+    nonexistent = set(indexed_files) - set(files)
+    if nonexistent:
+      print('The following files are in flyway.txt but not in the Flyway '
+            'directory: %s' % nonexistent)
+
+    # Do an ordering check on the index file (ignore the result, we're failing
+    # anyway).
+    has_valid_order(files_by_seqnum(indexed_files, 'flyway.txt'), 'flyway.txt')
+    success = False
+
+  if not success:
+    print('Please fix any conflicts and run "./nom_build :db:generateFlywayIndex"')
+
+  return not success
+
 
 def get_files():
   for root, dirnames, filenames in os.walk("."):
@@ -197,5 +282,10 @@ if __name__ == "__main__":
       failed = True
       print("%s had errors: \n  %s" % (file, "\n  ".join(error_messages)))
 
+  # And now for something completely different: check to see if the Flyway
+  # index is up-to-date.  It's quicker to do it here than in the unit tests:
+  # when we put it here it fails fast before all of the tests are run.
+  failed |= verify_flyway_index()
+
   if failed:
     sys.exit(1)
diff --git a/db/README.md b/db/README.md
index a082a5c44..f8abe7007 100644
--- a/db/README.md
+++ b/db/README.md
@@ -61,6 +61,11 @@ Below are the steps to submit a schema change:
     You'll want to have a look at the diffs in the golden schema to verify that
     all changes are intentional.
 
+5.  Run ./nom_build :db:generateFlywayIndex to regenerate the Flyway index.
+    This is a file listing all of the current Flyway files.  Its purpose is to
+    produce a merge conflict when more than one person adds a Flyway file with
+    the same sequence number.
+
 Relevant files (under db/src/main/resources/sql/schema/):
 
 *   nomulus.golden.sql is the schema dump (pg_dump for postgres) of the final
diff --git a/db/build.gradle b/db/build.gradle
index 888e0eaa7..a8efe0c82 100644
--- a/db/build.gradle
+++ b/db/build.gradle
@@ -170,6 +170,28 @@ dependencies {
   testCompile project(path: ':common', configuration: 'testing')
 }
 
+task generateFlywayIndex {
+  def flywayBase = "$projectDir/src/main/resources/sql/flyway"
+  def filenamePattern = /V(\d+)__.*\.sql/
+
+  def getSeqNum = { file ->
+    def match = file.getName() =~ filenamePattern
+    if (match.size() != 1) {
+      throw new IllegalArgumentException("Bad Flyway filename: $file")
+    }
+    return match[0][1] as int
+  }
+
+  doLast {
+    def files = new File(flywayBase).listFiles()
+    def indexFile = new File("${flywayBase}.txt")
+    indexFile.write ''
+    for (def file : files.sort{a, b -> getSeqNum(a) <=> getSeqNum(b)}) {
+      indexFile << "${file.name}\n"
+    }
+  }
+}
+
 flywayInfo.dependsOn('buildNeeded')
 flywayValidate.dependsOn('buildNeeded')
 
diff --git a/db/src/main/resources/sql/flyway.txt b/db/src/main/resources/sql/flyway.txt
new file mode 100644
index 000000000..fbb5317bd
--- /dev/null
+++ b/db/src/main/resources/sql/flyway.txt
@@ -0,0 +1,58 @@
+V1__create_claims_list_and_entry.sql
+V2__create_premium_list_and_entry.sql
+V3__create_registry_lock.sql
+V4__registry_lock_add_index_on_verification_code.sql
+V5__update_premium_list.sql
+V6__premium_list_bloom_filter.sql
+V7__update_claims_list.sql
+V8__registry_lock_registrar_index.sql
+V9__premium_list_currency_type.sql
+V10__create_reserved_list_and_entry.sql
+V11__premium_entry_reorder_column.sql
+V12__create_cursor.sql
+V13__refactor_registry_lock.sql
+V14__load_extension_for_hstore.sql
+V15__add_epp_resources.sql
+V16__create_registrar.sql
+V17__create_registrar_poc.sql
+V18__create_lock.sql
+V19__add_registry_relock_reference.sql
+V20__add_relock_duration.sql
+V21__add_registry_lock_email_to_poc.sql
+V22__update_ns_hosts.sql
+V23__create_contact.sql
+V24__domain_base_contacts.sql
+V25__rename_vkey_fields.sql
+V26__create_billing_event.sql
+V27__create_pollmessage.sql
+V28__superordinate_domain_vkey.sql
+V29__add_columns_for_transfer_data.sql
+V30__inet_address_converter.sql
+V31__client_id_to_registrar_id.sql
+V32__drop_unused_transafer_data_columns_in_contact.sql
+V33__create_host_history.sql
+V34__rename_fully_qualified_names.sql
+V35__rename_allow_list.sql
+V36__create_safebrowsing_threats.sql
+V37__update_spec11threatmatch.sql
+V38__create_contact_history.sql
+V39__add_updatetime_column.sql
+V40__spec11threatmatch_remove_registrar_foreign_key.sql
+V41__add_columns_to_domain.sql
+V42__add_txn_table.sql
+V43__update_relock_duration_type.sql
+V44__create_domain_history.sql
+V45__add_grace_period_table.sql
+V46__Contact_contactId_index_to_non_unique.sql
+V47__remove_spec11_domain_foreign_key.sql
+V48__domain_add_autorenew_end_time_column.sql
+V49__create_allocation_token.sql
+V50__use_composite_key_for_registrar_poc.sql
+V51__use_composite_primary_key_for_domain_history_table.sql
+V52__update_billing_constraint.sql
+V53__add_temp_history_id_sequence.sql
+V54__add_tld_table.sql
+V55__domain_history_fields.sql
+V56__rename_host_table.sql
+V57__history_null_content.sql
+V58__drop_default_value_and_sequences_for_billing_event.sql