From 5cfb8b1e17796056521b17143037a396f8f23beb Mon Sep 17 00:00:00 2001
From: Doug Blank <dblank@cs.brynmawr.edu>
Date: Sat, 23 Apr 2016 17:00:11 -0400
Subject: [PATCH] Postgresql and Mysql limit/offset

---
 gramps/plugins/database/dbapi.py              |  2 +-
 .../plugins/database/dbapi_support/mysql.py   | 11 +++++--
 .../database/dbapi_support/postgresql.py      | 32 +++++++++++++------
 3 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/gramps/plugins/database/dbapi.py b/gramps/plugins/database/dbapi.py
index c9e5ac862..da337fe40 100644
--- a/gramps/plugins/database/dbapi.py
+++ b/gramps/plugins/database/dbapi.py
@@ -1859,7 +1859,7 @@ class DBAPI(DbGeneric):
         if get_count_only:
             select_fields = ["1"]
         if start:
-            query = "SELECT %s FROM %s %s %s LIMIT %s, %s" % (
+            query = "SELECT %s FROM %s %s %s LIMIT %s, %s " % (
                 ", ".join(select_fields), table_name, where_clause, order_clause, start, limit
             )
         else:
diff --git a/gramps/plugins/database/dbapi_support/mysql.py b/gramps/plugins/database/dbapi_support/mysql.py
index 555fa54c5..cc92024e0 100644
--- a/gramps/plugins/database/dbapi_support/mysql.py
+++ b/gramps/plugins/database/dbapi_support/mysql.py
@@ -1,4 +1,5 @@
 import MySQLdb
+import re
 
 MySQLdb.paramstyle = 'qmark' ## Doesn't work
 
@@ -36,8 +37,14 @@ class MySQL(object):
         ## LIMIT offset, -1
         query = query.replace("LIMIT -1", 
                               "LIMIT 18446744073709551615") ##
-        ## FIXME: regex match:
-        #query = query.replace("LIMIT .*,-1", "LIMIT $1, ALL")
+        match = re.match(".* LIMIT (.*), (.*) ", query)
+        if match and match.groups():
+            offset, count = match.groups()
+            if count == "-1":
+                count = "18446744073709551615"
+            query = re.sub("(.*) LIMIT (.*), (.*) ", 
+                           "\\1 LIMIT %s, %s " % (offset, count),
+                           query)
         return query
 
     def execute(self, query, args=[]):
diff --git a/gramps/plugins/database/dbapi_support/postgresql.py b/gramps/plugins/database/dbapi_support/postgresql.py
index 1a5a05e4b..25f3415ed 100644
--- a/gramps/plugins/database/dbapi_support/postgresql.py
+++ b/gramps/plugins/database/dbapi_support/postgresql.py
@@ -1,4 +1,5 @@
 import psycopg2
+import re
 
 psycopg2.paramstyle = 'format'
 
@@ -23,13 +24,28 @@ class Postgresql(object):
         self.connection.autocommit = True
         self.cursor = self.connection.cursor()
 
+    def _hack_query(self, query):
+        query = query.replace("?", "%s")
+        query = query.replace("REGEXP", "~")
+        query = query.replace("desc", "desc_")
+        ## LIMIT offset, count
+        ## count can be -1, for all
+        ## LIMIT -1 
+        ## LIMIT offset, -1
+        query = query.replace("LIMIT -1", 
+                              "LIMIT all") ##
+        match = re.match(".* LIMIT (.*), (.*) ", query)
+        if match and match.groups():
+            offset, count = match.groups()
+            if count == "-1":
+                count = "all"
+            query = re.sub("(.*) LIMIT (.*), (.*) ", 
+                           "\\1 LIMIT %s OFFSET %s " % (count, offset),
+                           query)
+        return query
+
     def execute(self, *args, **kwargs):
-        sql = args[0]
-        sql = sql.replace("?", "%s")
-        sql = sql.replace("REGEXP", "~")
-        sql = sql.replace("desc", "desc_")
-        sql = sql.replace("LIMIT -1", "LIMIT all")
-        ## FIXME: limit offset, -1
+        sql = self._hack_query(args[0])
         if len(args) > 1:
             args = args[1]
         else:
@@ -56,10 +72,8 @@ class Postgresql(object):
         self.connection.rollback()
 
     def try_execute(self, sql):
-        sql = sql.replace("?", "%s")
+        sql = self._hack_query(sql)
         sql = sql.replace("BLOB", "bytea")
-        sql = sql.replace("desc", "desc_")
-        sql = sql.replace("LIMIT -1", "LIMIT all")
         try:
             self.cursor.execute(sql)
         except Exception as exc: