[patch] sqlite3 can't handle initial data with more than one statement

[jpellerin@…]

Using django trunk [2947], pysqlite 2.2.2 and sqlite 3.3.5, I can't include more than one statement in my models' initial data files, or sqlite chokes with an error: "You can only execute one statement at a time". Various googlable comments here and elsewhere indicate that there is some magical combination of sqlite version and pysqlite version that will make this work, but I've been unable to find it. Seems likely that others are probably unable also, so I think a workaround in django will be valuable.

Attached is a patch against [2947] django.core.management.py that uses a regular expression to split multiple statements in a model's sql initial data on ;, so that they can be fed to badly-behaving backends one at a time.

[jpellerin@…]

patch to split sql initial data into individual sql statements

[jpellerin@…]

Further information: according to the sqlite source, executing multiple sql statements in one execute() is explicitly disallowed by DB-API.

Ref: ​http://www.initd.org/tracker/pysqlite/changeset/177#file3

[Adrian Holovaty]

(In [2985]) Fixed #1935 -- Initial SQL data now works in SQLite if there are multiple statements. Thanks, jpellerin@…

[anonymous]

The current regular expression does not correctly handle ';' terminated SQL statements. Because the regular expression considers '\n' valid within an SQL statement, but ';' is considered a terminator, the following occurs:

ALTER TABLE "assets_company" ADD CONSTRAINT "vvalid_name" CHECK (LENGTH(name) != 3);

is parsed as:

['ALTER TABLE "assets_company" ADD CONSTRAINT "valid_name" CHECK (LENGTH(name) != 0)', '\n']

The postgresql driver errors out upon receiving a statement containing only '\n'. A patch to correctly handle statement termination is attached.

[landonf@…]

Comment to note non-anonymous source of regex patch and bug re-opening.

[Landon Fuller <landonf@…>]

I've updated the patch to also fix: #2034, #2044, and #2119. I've only tested against Postgesql. Pasting it inline as well as attaching it, since it's short:
Index: management.py
===================================================================
--- management.py (revision 3137)
+++ management.py (working copy)
@@ -337,9 +337,9 @@

r"""( # each statement is...
(?: # one or more chunks of ...

(?:[^{;'"]+) # not the end of a statement or start of a quote}

• | (?:'[^{']*') # something in single quotes}
• | (?:"[^{"]*") # something in double quotes}
• )+)""", re.VERBOSE)

+ | (?:'(?:[<sup>']|<?=\')*') # something in single quotes
+ | (?:"(?:[</sup>"]|<?=\")*") # something in double quotes
+ )+;?[ \t\n]?)""", re.VERBOSE)

# Find custom SQL, if it's available.
sql_files = [os.path.join(app_dir, "%s.%s.sql" % (opts.object_name.lower(), settings.DATABASE_ENGINE)),

[Landon Fuller <landonf@…>]

Okay, so I obviously don't know how to use wiki formatting. Sorry!

Index: management.py
===================================================================
--- management.py       (revision 3137)
+++ management.py       (working copy)
@@ -337,9 +337,9 @@
         r"""(           # each statement is...
         (?:             # one or more chunks of ...
             (?:[^;'"]+) # not the end of a statement or start of a quote
-          | (?:'[^']*') # something in single quotes
-          | (?:"[^"]*") # something in double quotes
-        )+)""", re.VERBOSE)
+          | (?:'(?:[^']|<?=\')*') # something in single quotes
+          | (?:"(?:[^"]|<?=\")*") # something in double quotes
+        )+;?[ \t\n]?)""", re.VERBOSE)
 
     # Find custom SQL, if it's available.
     sql_files = [os.path.join(app_dir, "%s.%s.sql" % (opts.object_name.lower(), settings.DATABASE_ENGINE)),

[Malcolm Tredinnick]

(In [3178]) Fixed #2119 -- fixed problems with splitting SQL statements into separate
statements. Uses a patch from eaw@… and some contributions from
jpellerin@…. Also fixes #2034 and #1935.

[David Rogers]

This may not be a worthwhile concern, but the current implementation does not properly account for SQL comments after a semicolon. Consider:

DROP VIEW "some_view" IF EXISTS;

CREATE VIEW "some_view" AS
    SELECT "some_field" FROM "some_table"
        LEFT JOIN "some_other_table" USING "some_other_id"
        WHERE ( "some_field" BETWEEN 1 AND 1000 )
; -- CREATE VIEW "some_view"

For an exceptionally large CREATE statement, the comments are helpful. SQLite will complain about making two queries in the same execute() statement, because the current code doesn't address trailing comments.