# How I fixed a table from postgres

**URL:** https://meta.discourse.org/t/how-i-fixed-a-table-from-postgres/218012
**Category:** Self-hosting
**Created:** [February 13, 2022, 2:55am UTC](https://meta.discourse.org/t/how-i-fixed-a-table-from-postgres/218012 "2022-02-13T02:55:35Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Mr.X\_Mr.X](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/mr.x_mr.x/32/126610_2.png) [@Mr.X\_Mr.X](https://meta.discourse.org/u/Mr.X_Mr.X)
#### Post date: [February 13, 2022, 2:55am UTC](https://meta.discourse.org/t/how-i-fixed-a-table-from-postgres/218012/1 "2022-02-13T02:55:35Z")

</div>

I’m writing this post regarding a postgres table missing chunk error that was failing my daily backups. I managed to sort it out and I want to lay out the method I’ve used in case it can be of use for someone else encountering this issue. **_By no means is this is a guide or professional instructions on how to solve properly postgres missing chunk errors_ be** cause I’m no expert and I did it without having much knowledge but it worked out in the end.

The error I was getting during backups:

```plaintext
 pg_dump: error: Dumping the contents of table "stylesheet_cache" failed: PQgetResult() failed.
 pg_dump: error: Error message from server: ERROR: missing chunk number 0 for toast value 1903804 in pg_toast_22663
 pg_dump: error: The command was: COPY public.stylesheet_cache (id, target, digest, content, created_at, updated_at, theme_id, source_map) TO stdout;

```

So the problem was in the stylesheet\_cache table, ERROR: missing chunk number 0 for toast value 1903804 in pg\_toast\_22663.

I’m using Discourse in Docker so here is what I did

```plaintext
ssh into the server
cd /path/to/discourse
./launcher rebuild app
su postgres -c "psql discourse"

```

Once I was in postgres I tried to REINDEX the table in hope it will solve the issue.

```plaintext
discourse=# select reltoastrelid::regclass from pg_class where relname = 'stylesheet_cache';
      reltoastrelid      
-------------------------
 pg_toast.pg_toast_18396
(1 row)

```

```plaintext
REINDEX table stylesheet_cache;
REINDEX table pg_toast.pg_toast_18396;
VACUUM analyze stylesheet_cache;

```

Tried to do the backup again, still failed, so I had to continue finding the corruption

I computed the total number of rows in my table with:

```plaintext
select count(*) from stylesheet_cache;

```

I got a count of 2260 rows.

I went to finding the exact row that is corrupted and delete it, somehow I assumed that stylesheet\_cache is not something that can really break my whole db. As I mentioned I’m no expert so maybe I took a too big of a leap of faith so be careful when doing this cause you could mess up your db.

I used the LIMIT and OFFSET queries to find the corrupted rows

```plaintext
select * from stylesheet_cache order by id limit 100 offset 0;

```

I played around with the offset and limit until I got the _Missing chunk…’_ error and then narrowed down to LIMIT 1 and offset the row that was corrupted. In my case there were 5 rows corrupted.

You could use a sh script to find the row with less effort, I went the manual way which took some time but you could use this:

```plaintext
#!/bin/sh
j=0
while [$j -lt 2260]
do
  psql -U postgres -d discourse -c "SELECT * FROM stylesheet_cache LIMIT 1 offset $j" >/dev/null || echo $j
  j=$(($j+1))
done

```

I went to find the id of the corrupted row with the following command:

```plaintext
select id from stylesheet_cache order by id limit 1 offset 450;

id

----

11498

```

So the id of my corrupted row was 11498  
I deleted the row with

```plaintext
delete from stylesheet_cache where id = 11498;

```

After deleting the corrupted rows I went to REINDEX again

```plaintext
REINDEX table stylesheet_cache;
REINDEX table pg_toast.pg_toast_40948;
VACUUM analyze stylesheet_cache;

```

And tried to backup again, this time it worked. I guided myself using this postgres recovery instructions: [Postgres error: Missing chunk 0 for toast value in pg\_toast · GitHub](https://gist.github.com/supix/80f9a6111dc954cf38ee99b9dedf187a)

_DISCLAIMER: this is not a expert opinion so proceed with caution if you have similar missing chunk corruptions and trying to fix them._