I have a repo that uses D1 with a very standard setup - D1 locally for developing, remote D1 for pro

I have a repo that uses D1 with a very standard setup - D1 locally for developing, remote D1 for production. Does anyone know of an example repo that demonstrates good tests practices for D1. Test isolation, etc?

Tim Reynolds•8/30/25, 8:46 PM

I'm sure you get this feedback a lot but with workers now supporting preview deploys it would be good to have proper branch based D1 environments that we're linked to a preview build, today as far as I'm aware you can only have a single preview D1 instance used across all branches. This is quite limiting compared to using other setups like Neon or supabase with say vercel.

Eesdee I have a repo that uses D1 with a very standard setup - D1 locally for developin...

mw10013•8/30/25, 9:50 PM

I found this example to be helpful: https://github.com/cloudflare/workers-sdk/tree/4492eb0490588df736c25272ed2b279736462c9a/fixtures/vitest-pool-workers-examples/d1

GitHub

workers-sdk/fixtures/vitest-pool-workers-examples/d1 at 4492eb04905...

Home to Wrangler, the CLI for Cloudflare Workers® - cloudflare/workers-sdk

workers-sdk/fixtures/vitest-pool-workers-examples/d1 at 4492eb04905...

TTim Reynolds I'm sure you get this feedback a lot but with workers now supporting preview dep...

lambrospetrou•8/31/25, 7:00 AM

Yeah, this would be cool. We discussed about it a few times and once we implement fork/clone this will come next.
No defined ETA unfortunately though as this work did not yet start.

Llambrospetrou Yeah, this would be cool. We discussed about it a few times and once we implemen...

Tim Reynolds•8/31/25, 7:02 AM

Thanks for the insight, did seem like it would need a bunch of additional features which might stem from having timetravel which I think was added more recently

Nooc•8/31/25, 7:52 AM

Hello, I want to know if I can transfer D1 databases from one account to another account?

James•8/31/25, 11:30 AM

Not directly. The best way would be to export it and then re-import it on another account I imagine.

sirhype•8/31/25, 7:56 PM

Is there somewhere I can find all the supported D1 column types? I thought I knew what they were, but apparently

TIMESTAMP

TIMESTAMP

is supported?

Ssirhype Is there somewhere I can find all the supported D1 column types? I thought I kne...

Chaika•8/31/25, 7:59 PM

It's all just Sqlite: https://www.sqlite.org/datatype3.html
There's no direct date/timestamp type, but it supports converting between text/real/int when you use date functions
Any type you specify that does not exist just fallbacks to numeric

sirhype•8/31/25, 7:59 PM

Ah, that's an interesting functionality. Thank you!

sirhype•8/31/25, 8:00 PM

Was confused because I saw this

sirhype•8/31/25, 8:00 PM

and it seemed to be treated as an integer

sirhype•8/31/25, 8:03 PM

but it's definitely not, so that makes sense now

Ssirhype and it seemed to be treated as an integer

Chaika•8/31/25, 8:06 PM

ah yea opps the default underlying type is numeric, but it can accept text/anything else so I always forget that

A column with NUMERIC affinity may contain values using all five storage classes. When text data is inserted into a NUMERIC column, the storage class of the text is converted to INTEGER or REAL (in order of preference) if the text is a well-formed integer or real literal, respectively. If the TEXT value is a well-formed integer literal that is too large to fit in a 64-bit signed integer, it is converted to REAL. For conversions between TEXT and REAL storage classes, only the first 15 significant decimal digits of the number are preserved. If the TEXT value is not a well-formed integer or real literal, then the value is stored as TEXT. For the purposes of this paragraph, hexadecimal integer literals are not considered well-formed and are stored as TEXT. (This is done for historical compatibility with versions of SQLite prior to version 3.8.6 2014-08-15 where hexadecimal integer literals were first introduced into SQLite.) If a floating point value that can be represented exactly as an integer is inserted into a column with NUMERIC affinity, the value is converted into an integer. No attempt is made to convert NULL or BLOB values.

a bit messy. There's implicit conversion everywhere so you can get away with a lot

sirhype•8/31/25, 8:28 PM

Thanks for the explanation!

sirhype•8/31/25, 8:28 PM

Another question, what are "Default SQLite extensions"

sirhype•8/31/25, 8:29 PM

Does it include these?

Ssirhype Another question, what are "Default SQLite extensions"

Chaika•8/31/25, 8:44 PM

hmm yea that's questionable documentation

The Sqlite compilation for D1 is part of the open source workerd but hard to read: https://github.com/cloudflare/workerd/blob/4c42a4a9d3390c88e9bd977091c9d3395a6cd665/build/BUILD.sqlite3#L13

More simply, there's an specific allowlist of functions you're allowed to use with D1:
https://github.com/cloudflare/workerd/blob/4c42a4a9d3390c88e9bd977091c9d3395a6cd665/src/workerd/util/sqlite.c%2B%2B#L269
Json and fts5 are the only ones allowed for extensions/not base (and I've used both before, they def work).
They also only allow specific Virtual Tables for fts5 and fts5vocab: https://github.com/cloudflare/workerd/blob/4c42a4a9d3390c88e9bd977091c9d3395a6cd665/src/workerd/util/sqlite.c%2B%2B#L1155 so anything that depends on Virtual Tables (like zipfiles, csv, etc) will def not work

CChaika hmm yea that's questionable documentation The Sqlite compilation for D1 is part...

lambrospetrou•9/1/25, 4:31 PM

We made the docs a bit more explicit now, although it's a bit hard to list every single extension that is enabled by default in SQLite 3.47: https://developers.cloudflare.com/d1/sql-api/sql-statements/#supported-sqlite-extensions

Thanks to @Jun for the prompt updates!

sirhype•9/1/25, 8:32 PM

Thank you both so much! This was super helpful!

bren.app•9/1/25, 11:24 PM

one bit of feedback I've noticed about the D1 Studio! I have a bunch of tables without a rowid (since they have TEXT UUID primary keys), and I've noticed that the studio loves to append rowid to queries, making almost all interactions fail. The most annoying here is individual updates.

bren.app•9/1/25, 11:24 PM

(I will say I moved a bunch of this data from KV to D1 and it's been a marked improvement for my usecase)

Bbren.app one bit of feedback I've noticed about the D1 Studio! I have a bunch of tables w...

Brayden•9/1/25, 11:31 PM

Thanks for the feedback @bren.app, we'll take a look!

BBrayden Thanks for the feedback @bren.app, we'll take a look!

bren.app•9/1/25, 11:32 PM

Schema of the table

CREATE TABLE users(
    key TEXT UNIQUE PRIMARY KEY NOT NULL, -- Long Hex String (182 chars)
    name TEXT NOT NULL,
    role TEXT NOT NULL DEFAULT 'none',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
) WITHOUT ROWID

CREATE TABLE users(
    key TEXT UNIQUE PRIMARY KEY NOT NULL, -- Long Hex String (182 chars)
    name TEXT NOT NULL,
    role TEXT NOT NULL DEFAULT 'none',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
) WITHOUT ROWID

and the generated query when I modified a cell in the table

UPDATE "main"."users" SET "role" = 'none' WHERE "key" = '<ID>' RETURNING rowid, *

UPDATE "main"."users" SET "role" = 'none' WHERE "key" = '<ID>' RETURNING rowid, *

Bbren.app Schema of the table ``` CREATE TABLE users( key TEXT UNIQUE PRIMARY KEY NOT...

Visal .In•9/2/25, 2:18 AM

I will look into it.

Zack•9/3/25, 9:58 AM

Hey, so thought I would just raise this here because I have no idea what is happening. We have a dev D1 database that we deployed on a branch via terraform to test out some stuff. Our main branch ran some other terraform 2 weeks ago and deleted this dev D1 database, however a dev worker that was connected to this D1 database can still read this fine even today. I didn't even realise anything was wrong until I went to run new terraform today on this branch and it complained that the database was missing and needed to be re-created. Not sure what's going on here but feels weird (even though maybe nice for some people if they make a mistake) for the database to just sit around for 2 weeks when it shows as deleted in the dashboard. Who knows how long it''ll actually live on for. The database ID is/was

04a58760-3751-4337-bb3f-29a671a98cdd

04a58760-3751-4337-bb3f-29a671a98cdd

and the worker still connected to it is

tiles-dev

tiles-dev

in our account, specifically deployment

76803c37

76803c37

ZZack Hey, so thought I would just raise this here because I have no idea what is happ...

lambrospetrou•9/3/25, 12:45 PM

Your database is indeed marked deleted in our database (API) (on 2025-08-19 11:51:40.308558+00). When at that point of the delete request we cannot communicate with the DB itself, we have an async flow for the DB (DO) itself to mark itself as deleted on the next heartbeat. I am looking into why that part failed.

Dean•9/4/25, 2:59 AM

is DB performance still impacted in WNAM? seeing pretty slow queries although the query latency metrics looks normal.

Dean•9/4/25, 3:01 AM

"wallTime": 13142 :NotLikeThis:

Dean•9/4/25, 3:22 AM

and magically fixed /shrug

maguayo•9/4/25, 9:38 AM

Hello! I tried D1 like 8 months ago (I think it was in beta). In the website it was anounced as "distributed" or that you could have read replicas in other countries, but in reality that feature wasn't there yet, is it there now? anyone have this information?

Mmaguayo Hello! I tried D1 like 8 months ago (I think it was in beta). In the website it ...

cloudkite•9/4/25, 9:44 AM

https://developers.cloudflare.com/d1/best-practices/read-replication/

Cloudflare Docs

Global read replication

D1 read replication can lower latency for read queries and scale read throughput by adding read-only database copies, called read replicas, across regions globally closer to clients.

Ccloudkite https://developers.cloudflare.com/d1/best-practices/read-replication/

maguayo•9/4/25, 9:45 AM

some of this documentation existed before it was posible to do it, that's why I'm asking for a confirmation if someone is using them

Mmaguayo some of this documentation existed before it was posible to do it, that's why I'...

cloudkite•9/4/25, 9:48 AM

From memory I don’t think there was docs prior to release, but there was a blog post outlining plans and approach

Mmaguayo Hello! I tried D1 like 8 months ago (I think it was in beta). In the website it ...

cloudkite•9/4/25, 9:50 AM

Depending on what you are building durable object SQLite might work better

Mmaguayo some of this documentation existed before it was posible to do it, that's why I'...

lambrospetrou•9/4/25, 12:33 PM

This documentation did not exist before we launched read replication. You are probably remembering something else.
Read replication is supported in D1 for a few months now, in beta yet until we fully implement some nice improvements around replica placement.

What is your use-case?

Llambrospetrou This documentation did not exist before we launched read replication. You are pr...

Larry•9/4/25, 1:31 PM

It's not docs, but this post from 2022 which has this line, "For D1 today, we... dynamically manage the number and location of read-only replicas..." is on the 1st page results when I Google "read-only replicas Cloudflare D1". [https://blog.cloudflare.com/whats-new-with-d1/]

LLarry It's not docs, but this post from 2022 which has this line, "For D1 today, we......

lambrospetrou•9/4/25, 2:57 PM

I think that was for the alpha version of D1, which had completely different architecture from D1 today. Will ping a team internally to see if we can somehow promote the new read replication stuff to surface higher in SEO.

Although googling d1 read replicationd1 read replication shows the right material in my own tabs and incognito right at the top.

Llambrospetrou I think that was for the alpha version of D1, which had completely different arc...

lambrospetrou•9/4/25, 3:01 PM

Actually, also read-only replicas Cloudflare D1read-only replicas Cloudflare D1 shows the new posts as well.

@Larry where did you see the old post surfacing?

Llambrospetrou Actually, also `read-only replicas Cloudflare D1` shows the new posts as well. ...

Larry•9/4/25, 3:22 PM

When I go incognito, it's not on the 1st page so the algorithm must take into account something about me. I wasn't trying to catch anyone out, I was just trying to explain where the confusion might be coming from. An easier fix for that one page than SEO might be to add an update notice to the blog post itself.

LLarry When I go incognito, it's not on the 1st page so the algorithm must take into ac...

lambrospetrou•9/4/25, 4:12 PM

Yes I already started the banner/notice discussion but I was wondering about the search since I didn't get it

aza547•9/5/25, 7:53 AM

Hello, when I hit the "Enable read replication" button in the dashboard nothing happens. It pulses for a moment then re-appears.

Aaza547 Hello, when I hit the "Enable read replication" button in the dashboard nothing ...

lambrospetrou•9/5/25, 12:53 PM

Do you get any error banner? (jeez, that yellow is rough

)

aza547•9/5/25, 12:57 PM

No error banner I'm afraid

Aaza547 No error banner I'm afraid

lambrospetrou•9/5/25, 1:14 PM

So you still have issues with it? Just saying the obvious, but did you make sure to refresh in case the dashboard accumulated some weird state?
Otherwise, if you still get noop clicks DM me your account and database IDs and i can take a look.

aza547•9/5/25, 1:15 PM

yeah still the same, will DM you

Bbren.app one bit of feedback I've noticed about the D1 Studio! I have a bunch of tables w...

Visal .In•9/5/25, 1:47 PM

The fix lands in production now. Let me know if you still encounter any other problem

Llambrospetrou So you still have issues with it? Just saying the obvious, but did you make sure...

lambrospetrou•9/5/25, 2:00 PM

Just to circle back on that. It's not a read replication issue, there is a regression in our API that returns always "disabled" for read replication mode hence the UI always shows that.
Read replication is still enabled though, and works fine.
We are making a fix now to the API and hopefully will be out by end of the day.

OOr We're seeing an increase of the following error: "D1 DB is overloaded. Too many ...

lambrospetrou•9/5/25, 5:49 PM

https://developers.cloudflare.com/d1/observability/debug-d1/#error-list

That means you send more requests than what your DB can process. It's not a fixed number limit since it depends on your queries. D1 is single threaded, so the slower the queries, the less amount it can execute. Some users do more than 1K/sec, others can only do 10/s.

CREATE TABLE users( key TEXT UNIQUE PRIMARY KEY NOT NULL, -- Long Hex String (182 chars) name TEXT NOT NULL, role TEXT NOT NULL DEFAULT 'none', created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP, updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ) WITHOUT ROWID

I have a repo that uses D1 with a very standard setup - D1 locally for developing, remote D1 for pro

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