Xata

Documentation Index

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• pgstreamsource refers to the user provided in the pgstream source URL.
• pgstreamtarget refers to the user provided in the pgstream target URL.

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Snapshots

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From Xata Database (Snapshots)

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Quick Checklist

• Create a source user (pgstreamsource) with access to required schemas/tables.
• For roles without passwords → no special config needed.
• For roles with passwords → must use the xata superuser.
• Update YAML config with correct snapshot settings.

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Steps

1. User privileges Ensure the pgstreamsource user (from the pgstream source URL) can access the database schema and tables you need.
2. Roles handling
   • No roles → no changes required.
   • Roles without passwords → no changes required.
   • Roles with passwords → must use the xata user as pgstreamsource. ⚠️ Only the xata user has access to the pg_authid table required for snapshotting roles with passwords. Without this, you’ll see:
     pg_dumpall: error: query failed: ERROR:  permission denied for table pg_authid
     
3. Config when not snapshotting roles If roles are disabled or not manually managed, add the following to avoid failures:
   snapshot:
     schema:
       pgdump_pgrestore:
         roles_snapshot_mode: "disabled"
         no_owner: true
         no_privileges: true
   
   Example full configuration:
   source:
     postgres:
       url: "postgresql://pgstreamsource:password@<xata-host>:5432/db?sslmode=require"
       mode: snapshot
       snapshot:
         mode: full # schema + data
         tables: ["public.*"] # all tables in the public schema
         schema:
           mode: pgdump_pgrestore
           pgdump_pgrestore:
             roles_snapshot_mode: "disabled"
             no_owner: true
             no_privileges: true
   

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To Xata Database (Snapshots)

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Quick Checklist

• Create a target user (pgstreamtarget) for the pgstream target URL.
• Grant privileges for schema/database ownership.
• Grant optional privileges depending on features (create DB, create roles).
• Use disable_triggers: false (required for all non-xata users).

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Steps

• Schema ownership
  ALTER DATABASE db OWNER TO pgstreamtarget;
  ALTER SCHEMA public OWNER TO pgstreamtarget;
  
• Database creation (if create_target_db is enabled)
  ALTER ROLE pgstreamtarget CREATEDB;
  
• Role creation (if roles_snapshot_mode is enabled/no_passwords)
  ALTER ROLE pgstreamtarget CREATEROLE;
  
  ⚠️ pgstreamtarget must already hold any privileges it assigns (e.g., REPLICATION).
• Disable triggers (required for Xata) ⚠️ Only the xata user can set session_replication_role on Xata databases. For all other users, you must disable trigger management in pgstream:
  target:
    postgres:
      disable_triggers: false # Required for non-xata users
  
  ❌ If using a non-xata user with disable_triggers: true, pgstream will fail with:
  permission denied to set parameter "session_replication_role"
  

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Replication

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From Xata Database (Replication)

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Quick Checklist

• Ensure logical replication is enabled on your Xata database.
• Use the xata user for initialization (only user with event trigger privileges).
• Optionally use a different pgstreamsource user for streaming.

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Steps

1. Enable logical replication Make sure logical replication is enabled in your database. The wal_level must be set to logical. You can check the current setting by running the following:
   SHOW wal_level;
   
   
   ⚠️ Changing wal_level requires a full database restart.
2. Replication phases
   • Initialization → requires elevated privileges to create schemas, event triggers, and replication slots.
   • Streaming → can use a dedicated pgstreamsource user.

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Initialization

• Creates pgstream schema
• Creates replication slot (if missing)
• Creates event triggers/functions for schema changes

source:
  postgres:
    url: "postgresql://xata:password@<xata-host>:5432/db?sslmode=require"
    mode: replication

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Streaming

• Keep using xata, or
• Transfer ownership to a dedicated pgstreamsource role.

-- Allow ownership transfer
GRANT pgstreamsource TO current_user;

-- Transfer ownership
ALTER DATABASE db OWNER TO pgstreamsource;
ALTER SCHEMA pgstream OWNER TO pgstreamsource;
ALTER SCHEMA <schema> OWNER TO pgstreamsource;
ALTER TABLE pgstream.schema_log OWNER TO pgstreamsource;
ALTER TABLE pgstream.table_ids OWNER TO pgstreamsource;
ALTER SEQUENCE pgstream.xid_serial OWNER TO pgstreamsource;

-- Replication privileges
ALTER ROLE pgstreamsource REPLICATION;

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To Xata Database (Replication)

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Quick Checklist

• Ensure pgstreamtarget has schema/database ownership.
• If combined with snapshot → follow Snapshot target requirements.

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Steps

ALTER DATABASE db OWNER TO pgstreamtarget;
ALTER SCHEMA <schema> OWNER TO pgstreamtarget;

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Troubleshooting