# HG changeset patch
# User Jun Wu <quark@fb.com>
# Date 1466674198 -3600
# Node ID 581f72f9478b852808abe2978b7500dc750f0e87
# Parent  ea4d6142c6d9cd07b591f371f779285d3002a7c3
maps: do not ask sqlite for min(rev), max(rev) together

When min(rev) and max(rev) are being asked in a single sql query, sqlite is
not smart enough to use the index and will iterate all rows.

This patch splits the query so it could be answered instantly.

diff --git a/hgsubversion/maps.py b/hgsubversion/maps.py
--- a/hgsubversion/maps.py
+++ b/hgsubversion/maps.py
@@ -567,13 +567,8 @@ class SqliteRevMap(collections.MutableMa
         self._db = None
         self._hashes = None
         self._opendb()
-        # update firstpulled, lastpulled
         self.firstpulled = 0
-        for row in self._query('SELECT MIN(rev), MAX(rev) FROM revmap'):
-            if row != (None, None):
-                self.firstpulled, lastpulled = row
-                if lastpulled > self.lastpulled:
-                    self.lastpulled = lastpulled
+        self._updatefirstlastpulled()
         # __iter__ is expensive and thus disabled by default
         # it should only be enabled for testing
         self._allowiter = False
@@ -748,6 +743,14 @@ class SqliteRevMap(collections.MutableMa
             f.write('%s\n' % self.VERSION)
             f.close()
 
+    def _updatefirstlastpulled(self):
+        sql = 'SELECT rev FROM revmap ORDER BY rev %s LIMIT 1'
+        for row in self._query(sql % 'ASC'):
+            self.firstpulled = row[0]
+        for row in self._query(sql % 'DESC'):
+            if row[0] > self.lastpulled:
+                self.lastpulled = row[0]
+
     @util.gcdisable
     def _importrevmapv1(self):
         with open(self._filepath, 'r') as f: