[IMP] util/pg: deduplicate "{parallel_filter}"

As usual, it reduces chances of stupid mistakes (e.g. typos).

Author: Pirols

src/util/pg.py

@@ -45,6 +45,7 @@
 
 ON_DELETE_ACTIONS = frozenset(("SET NULL", "CASCADE", "RESTRICT", "NO ACTION", "SET DEFAULT"))
 MAX_BUCKETS = int(os.getenv("MAX_BUCKETS", "150000"))
+PARALLEL_FILTER = "{parallel_filter}"
 
 
 class PGRegexp(str):
@@ -252,9 +253,9 @@ def explode_query_range(cr, query, table, alias=None, bucket_size=10000, prefix=
 
     alias = alias or table
 
-    if "{parallel_filter}" not in query:
+    if PARALLEL_FILTER not in query:
         sep_kw = " AND " if re.search(r"\sWHERE\s", query, re.M | re.I) else " WHERE "
-        query += sep_kw + "{parallel_filter}"
+        query += sep_kw + PARALLEL_FILTER
 
     cr.execute(format_query(cr, "SELECT min(id), max(id) FROM {}", table))
     min_id, max_id = cr.fetchone()
@@ -297,10 +298,10 @@ def explode_query_range(cr, query, table, alias=None, bucket_size=10000, prefix=
         # Still, since the query may only be valid if there is no split, we force the usage of `prefix` in the query to
         # validate its correctness and avoid scripts that pass the CI but fail in production.
         parallel_filter = "{alias}.id IS NOT NULL".format(alias=alias)
-        return [query.replace("{parallel_filter}", parallel_filter)]
+        return [query.replace(PARALLEL_FILTER, parallel_filter)]
 
     parallel_filter = "{alias}.id BETWEEN %(lower-bound)s AND %(upper-bound)s".format(alias=alias)
-    query = query.replace("%", "%%").replace("{parallel_filter}", parallel_filter)
+    query = query.replace("%", "%%").replace(PARALLEL_FILTER, parallel_filter)
     return [
         cr.mogrify(query, {"lower-bound": ids[i], "upper-bound": ids[i + 1] - 1}).decode() for i in range(len(ids) - 1)
     ]