orders: Optimization

Matching the accounts with a regular expression allows to extract all
the records with only one BQL query thus not requiring multiple
iterations through the transactions in the ledger.

The regular expression could be further optimized, see Emacs
regexp-opt function, but it is probably not worth the effort.

orders.py

@@ -32,6 +32,21 @@ EMPTY = frozenset()
 ZERO = decimal.Decimal('0.00')
 
 
+def commonprefix(words):
+    words = sorted(words)
+    w1, w2 = words[0], words[-1]
+    for i in range(len(w1)):
+        if w1[i] != w2[i]:
+            return w1[:i]
+    return w1
+
+
+def reopts(words):
+    prefix = commonprefix(words)
+    n = len(prefix)
+    return '{}(?:{})$'.format(re.escape(prefix), '|'.join(re.escape(w[n:]) for w in words))
+
+
 @contextlib.contextmanager
 def atomic(filepath):
     tmp = filepath + '~tmp'
@@ -938,25 +953,23 @@ def balance(conf, year):
     assert not errors
 
     accounts = list_designated_accounts(entries)
+    expr = reopts(accounts)
 
     entries = [apply_effective_date(entry, 'payment-date') for entry in entries]
 
-    r = []
-    for account in accounts:
-        types, rows = query.run_query(entries, options, f"""
-            SELECT
-              account,
-              flag = '*' AS key,
-              SUM(position) AS total
-            WHERE
-              year = {year} AND
-              account = '{account}' AND
-              flag != 'P'
-            GROUP BY
-              account, key""")
-        r.extend(rows)
-
-    t1 = petl.pushheader(r, [name for name, rtype in types]) \
+    types, rows = query.run_query(entries, options, f"""
+        SELECT
+          account,
+          flag = '*' AS key,
+          sum(position) AS total
+        WHERE
+          year = {year} AND
+          account ~ '{expr}' AND
+          flag != 'P'
+        GROUP BY
+          account, key""")
+
+    t1 = petl.pushheader(rows, [name for name, rtype in types]) \
              .convert('key', lambda v: 'POSTED' if v else 'BOOKED') \
              .convert('total', lambda v: v.get_only_position().units)
 
@@ -1146,7 +1159,7 @@ def acks(conf):
     assert not errors
 
     accounts = list_designated_accounts(entries)
-    expr = r'(?:{})$'.format('|'.join(re.escape(a) for a in accounts))
+    expr = reopts(accounts)
 
     types, rows = query.run_query(entries, options, f"""
         SELECT