Document: WM-097                                                 P. Webb
Category: Tutorial                                            2026-06-22

                    How to migrate from Gel to Disc

Abstract

   The hardest part is getting your data out of Gel in a useable format,
   the rest is easy (but mind your links on the way in, warning near
   the end).

Body

   Dumping your Gel database to a format other databases can read
   requires arcane knowledge but don’t fret, I’ve uncovered the
   incantations to free your data!

   Perform this full backup, for peace of mind.

   

   gel dump --all --format=dir gel-export



   You should see something like:

   

   Connecting to Gel instance 'INSTANCE' at localhost:PORT...
   Starting dump for database `'DATABASE'`...
     Finished dump for `'DATABASE'`. Total size: 181.67 KiB



   This will create gel-export in your current directory. Take note of
   the instance and database names and the port as you’ll need these
   later. Next, grab the password to your database:

   

   gel instance credentials --insecure-dsn -I INSTANCE



   You should see something like:

   

   gel:///DATABASE?port=PORT&password=PASSWORD&tls_ca_file=%3C...%3E&tls_security=no_host_verification



   Now we can set some variables to make the last bits pseudo-legible.
   sslmode=require because Gel refuses plaintext connections, and
   without it psql fails with a misleading auth error before the real
   "TLS required" one.

   

   DSN="postgresql://edgedb@localhost:PORT/DATABASE?sslmode=require"



   

   export PGPASSWORD="PASSWORD"



   Gel’s binary dump is useless to anything but Gel, so to get tabular
   data out we go through its SQL adapter. List the tables into a .tsv
   first, without any escaping that could mangle the identifiers:

   

   psql "$DSN" -At -F $'\t' -c "
     SELECT table_schema, table_name
     FROM information_schema.tables
     WHERE table_schema NOT IN ('information_schema', 'pg_catalog')
   " > gel-export/tables.tsv



   Create our final export directory:

   

   mkdir gel-export/data



   Finally, we render our .csvs:

   

   while IFS=$'\t' read -r schema table; do
     out="${schema}_${table}"
     psql "$DSN" --csv -c "SELECT * FROM \"$schema\".\"$table\"" > "gel-export/data/$out.csv"
   done < gel-export/tables.tsv



   


   A quick note on what’s in those CSVs, because it bites at import
   time (and it bit me)!

   Gel maps each object type to a table with id and __type__
   columns, single properties as plain columns, and (what got me) single
   LINKS as <link>_id UUID columns (your owner link becomes an
   owner_id column holding the target’s id).

   Multi links and multi properties aren’t in these tables at all; they
   live in their own source/target tables and import as
   separate files.

   


   I’ll assume you installed Disc[1] already. Great! You’ll need to get
   it setup with your schema. Run that migration!

   

   disc migrate



   Next, we’ll point Disc at your fresh collection of .csvs:

   

   disc db import ./gel-export/data



   This SHOULD work; it didn’t for me because…

   

   ✗ Import failed (transaction rolled back): duplicate key value violates unique constraint "log_pkey"



   …and that’s irrelevant to me. Ignoring conflicts like this is okay.

   

   disc db import ./gel-export/data --on-conflict skip



   


   You’ll get an import manifest of what was processed and skipped.
   Remember those <link>_id columns? Disc resolves them into your
   single links, but anything it can’t map surfaces here as a warning.
   Confirm your links got set and that no non-empty column was
   quietly discarded.

   A previous version of Disc silently dropped every <link>_id column
   and because I’m dogfooding this, I found the issue and fixed. This is
   bleeding edge folks!

   


   Run disc serve and navigate to your database’s /ui and you should
   see populated objects in the Data tab.

   Voila! Now all you gotta do is update your codebase…unfortunately,
   you’ve gotta handle that yourself. 🕸️