[issue13299] namedtuple row factory for sqlite3

Zaur Shibzukhov added the comment: Instead of using cache, maybe better to use mutable default argument? For example: def make_row_factory(cls_factory, **kw): def row_factory(cursor, row, cls=[None]): rf = cls[0] if rf is None: fields = [col[0] for col in

[issue13299] namedtuple row factory for sqlite3

Raymond Hettinger added the comment: FWIW, namedtuple speed improved considerably since these posts were made. When I last checked, their lookup speed was about the same as a dict lookup. See: https://docs.python.org/3/whatsnew/3.9.html#optimizations --

[issue13299] namedtuple row factory for sqlite3

Erlend E. Aasland added the comment: See also bpo-39170 -- ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue13299] namedtuple row factory for sqlite3

Change by Erlend Egeberg Aasland : -- nosy: +erlendaasland ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue13299] namedtuple row factory for sqlite3

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[issue13299] namedtuple row factory for sqlite3

YoSTEALTH added the comment: note: sqlite_namedtuplerow.patch _cache method conflicts with attached database with say common table.column name like id Using namedtuple method over sqlite3.Row was a terrible idea for me. I thought namedtuple is like tuple so should be faster then dict! wrong.

[issue13299] namedtuple row factory for sqlite3

Serhiy Storchaka added the comment: Here is faster implementation. $ ./python -m timeit -s import sqlite3; con = sqlite3.connect(':memory:'); con.row_factory = sqlite3.NamedTupleRow; con.execute('create table t (a, b)') -s for i in range(100): con.execute('insert into t values (1, 2)') --

[issue13299] namedtuple row factory for sqlite3

Changes by Gerhard Häring g...@ghaering.de: -- assignee: - ghaering ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299 ___ ___ Python-bugs-list

[issue13299] namedtuple row factory for sqlite3

Daniel Lenski added the comment: Serhiy, 52 usec/loop doesn't seem like much overhead. This is not 52 usec per row fetched, but just 52 usec per cursor.execute(). An example where 1 row is fetched for each cursor would show this more clearly. The advantage of namedtuple is that it's a very

[issue13299] namedtuple row factory for sqlite3

Serhiy Storchaka added the comment: Yes, above microbenchmarks measure the time of execute() + the time of fetching one row. Here is more precise microbenchmarks. $ ./python -m timeit -s import sqlite3; con = sqlite3.connect(':memory:'); con.execute('create table t (a, b)') -s for i in

[issue13299] namedtuple row factory for sqlite3

Mark Lawrence added the comment: I'd like to see this in 3.5 as I often use sqlite so what needs doing here? -- nosy: +BreamoreBoy versions: +Python 3.5 -Python 3.4 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299

[issue13299] namedtuple row factory for sqlite3

Serhiy Storchaka added the comment: There is significant overhead. Microbenchmark results: $ ./python -m timeit -s import sqlite3; con = sqlite3.connect(':memory:') con.execute('select 1 as a, 2 as b').fetchall() 1 loops, best of 3: 35.8 usec per loop $ ./python -m timeit -s import

[issue13299] namedtuple row factory for sqlite3

Changes by Glenn Langford glenn.langf...@gmail.com: -- nosy: -glangford ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299 ___ ___

[issue13299] namedtuple row factory for sqlite3

Glenn Langford added the comment: In abstract, I like the namedtuple interface for sqlite3 as well. One caution is that the approach suggested at http://peter-hoffmann.com/2010/python-sqlite-namedtuple-factory.html can have a dramatic impact on performance. For one DB-intensive application,

[issue13299] namedtuple row factory for sqlite3

Glenn Langford added the comment: ...if I understand the proposed caching scheme, then repeated executions of the query SELECT a,b,c FROM table would result in cache hits, since the column names remain the same. I'm guessing this would resolve the performance problem in the app I saw, but it

[issue13299] namedtuple row factory for sqlite3

Changes by Ezio Melotti ezio.melo...@gmail.com: -- stage: needs patch - patch review versions: +Python 3.4 -Python 3.3 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299 ___

[issue13299] namedtuple row factory for sqlite3

Raymond Hettinger added the comment: Caching based on the cursor going to be problematic because a single cursor can be used multiple times with different descriptions: c = conn.cursor() c.execute('select symbol from stocks') print c.description c.execute('select price from

[issue13299] namedtuple row factory for sqlite3

Russell Sim added the comment: Raymond, Thanks for the comprehensive feedback! It's fantastic! I have updated the patch with most of you feedback... but there was one part that I couldn't follow entirely. I am now using the _make method but I have had to use star unpacking to allow the

[issue13299] namedtuple row factory for sqlite3

Nick Coghlan added the comment: You should be able to just use tuple(col[0] for col in cursor.description) instead of the current list comprehension in order to make the argument hashable. -- ___ Python tracker rep...@bugs.python.org

[issue13299] namedtuple row factory for sqlite3

Russell Sim added the comment: Nick, Thanks for the tip. I have removed the star unpacking. -- Added file: http://bugs.python.org/file26946/issue_13299.2.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299

[issue13299] namedtuple row factory for sqlite3

Russell Sim added the comment: Hi, Here is an implementation using lru_cache to prevent regeneration of the named tuple each time. Cheers, Russell -- keywords: +patch nosy: +Russell.Sim Added file: http://bugs.python.org/file26909/issue_13299.patch

[issue13299] namedtuple row factory for sqlite3

Changes by Petri Lehtinen pe...@digip.org: -- nosy: +petri.lehtinen ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299 ___ ___ Python-bugs-list

[issue13299] namedtuple row factory for sqlite3

Éric Araujo mer...@netwok.org added the comment: collections.namedtuple provides a much nicer interface than sqlite3.Row Definitely! -- nosy: +eric.araujo ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299

[issue13299] namedtuple row factory for sqlite3

Raymond Hettinger raymond.hettin...@gmail.com added the comment: +1 -- nosy: +rhettinger ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299 ___

[issue13299] namedtuple row factory for sqlite3

New submission from Nick Coghlan ncogh...@gmail.com: Currently, sqlite3 allows rows to be easily returned as ordinary tuples (default) or sqlite3.Row objects (which allow dict-style access). collections.namedtuple provides a much nicer interface than sqlite3.Row for accessing ordered data

[issue13299] namedtuple row factory for sqlite3

Changes by Ned Deily n...@acm.org: -- nosy: +ghaering ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13299 ___ ___ Python-bugs-list mailing list