commit 4a926caf8e5fd8af771b2c34bfb6e91c732331fe
author Berker Peksag <berker.peksag@gmail.com> Sun Feb 26 18:22:38 2017 +0300
committer GitHub <noreply@github.com> Sun Feb 26 18:22:38 2017 +0300
tree bddaa3a91ef435b1b18716b8385a6415c55fbd13
parent 46ce7599af82a929506baeaaee5c149970440c4c

bpo-28518: Start a transaction implicitly before a DML statement (#245)

Patch by Aviv Palivoda.

Modules/_sqlite/cursor.c

diff --git a/Modules/_sqlite/cursor.c b/Modules/_sqlite/cursor.c
index 39f7a65..8341fb8 100644
--- a/Modules/_sqlite/cursor.c
+++ b/Modules/_sqlite/cursor.c
@@ -511,10 +511,9 @@
     pysqlite_statement_reset(self->statement);
     pysqlite_statement_mark_dirty(self->statement);
 
-    /* For backwards compatibility reasons, do not start a transaction if a
-       DDL statement is encountered.  If anybody wants transactional DDL,
-       they can issue a BEGIN statement manually. */
-    if (self->connection->begin_statement && !sqlite3_stmt_readonly(self->statement->st) && !self->statement->is_ddl) {
+    /* We start a transaction implicitly before a DML statement.
+       SELECT is the only exception. See #9924. */
+    if (self->connection->begin_statement && self->statement->is_dml) {
         if (sqlite3_get_autocommit(self->connection->db)) {
             result = _pysqlite_connection_begin(self->connection);
             if (!result) {
@@ -609,7 +608,7 @@
             }
         }
 
-        if (!sqlite3_stmt_readonly(self->statement->st)) {
+        if (self->statement->is_dml) {
             self->rowcount += (long)sqlite3_changes(self->connection->db);
         } else {
             self->rowcount= -1L;

Modules/_sqlite/statement.c

diff --git a/Modules/_sqlite/statement.c b/Modules/_sqlite/statement.c
index 8b45a03..27b2654 100644
--- a/Modules/_sqlite/statement.c
+++ b/Modules/_sqlite/statement.c
@@ -73,8 +73,9 @@
     Py_INCREF(sql);
     self->sql = sql;
 
-    /* determine if the statement is a DDL statement */
-    self->is_ddl = 0;
+    /* Determine if the statement is a DML statement.
+       SELECT is the only exception. See #9924. */
+    self->is_dml = 0;
     for (p = sql_cstr; *p != 0; p++) {
         switch (*p) {
             case ' ':
@@ -84,9 +85,10 @@
                 continue;
         }
 
-        self->is_ddl = (PyOS_strnicmp(p, "create ", 7) == 0)
-                    || (PyOS_strnicmp(p, "drop ", 5) == 0)
-                    || (PyOS_strnicmp(p, "reindex ", 8) == 0);
+        self->is_dml = (PyOS_strnicmp(p, "insert ", 7) == 0)
+                    || (PyOS_strnicmp(p, "update ", 7) == 0)
+                    || (PyOS_strnicmp(p, "delete ", 7) == 0)
+                    || (PyOS_strnicmp(p, "replace ", 8) == 0);
         break;
     }
 

Modules/_sqlite/statement.h

diff --git a/Modules/_sqlite/statement.h b/Modules/_sqlite/statement.h
index 6eef168..8db10f6 100644
--- a/Modules/_sqlite/statement.h
+++ b/Modules/_sqlite/statement.h
@@ -38,7 +38,7 @@
     sqlite3_stmt* st;
     PyObject* sql;
     int in_use;
-    int is_ddl;
+    int is_dml;
     PyObject* in_weakreflist; /* List of weak references */
 } pysqlite_Statement;