Commits on Apr 13, 2024

1. Fix FK constraints for compressed chunks …

   When foreign key support for compressed chunks was added we moved
   the FK constraint from the uncompressed chunk to the compressed chunk as
   part of compress_chunk and moved it back as part of decompress_chunk.
   With the addition of partially compressed chunks in 2.10.x this approach
   was no longer sufficient and the FK constraint needs to be present on
   both the uncompressed and the compressed chunk.
   
   While this patch will fix future compressed chunks a migration has to be
   run after upgrading timescaledb to migrate existing chunks affected by
   this.
   
   The following code will fix any affected hypertables:
   ```
   CREATE OR REPLACE FUNCTION pg_temp.constraint_columns(regclass, int2[]) RETURNS text[] AS
   $$
     SELECT array_agg(attname) FROM unnest($2) un(attnum) LEFT JOIN pg_attribute att ON att.attrelid=$1 AND att.attnum = un.attnum;
   $$ LANGUAGE SQL SET search_path TO pg_catalog, pg_temp;
   
   DO $$
   DECLARE
     ht_id int;
     ht regclass;
     chunk regclass;
     con_oid oid;
     con_frelid regclass;
     con_name text;
     con_columns text[];
     chunk_id int;
   
   BEGIN
   
     -- iterate over all hypertables that have foreign key constraints
     FOR ht_id, ht in
       SELECT
         ht.id,
         format('%I.%I',ht.schema_name,ht.table_name)::regclass
       FROM _timescaledb_catalog.hypertable ht
       WHERE
         EXISTS (
           SELECT FROM pg_constraint con
           WHERE
             con.contype='f' AND
             con.conrelid=format('%I.%I',ht.schema_name,ht.table_name)::regclass
         )
     LOOP
       RAISE NOTICE 'Hypertable % has foreign key constraint', ht;
   
       -- iterate over all foreign key constraints on the hypertable
       -- and check that they are present on every chunk
       FOR con_oid, con_frelid, con_name, con_columns IN
         SELECT con.oid, con.confrelid, con.conname, pg_temp.constraint_columns(con.conrelid,con.conkey)
         FROM pg_constraint con
         WHERE
           con.contype='f' AND
           con.conrelid=ht
       LOOP
         RAISE NOTICE 'Checking constraint % %', con_name, con_columns;
         -- check that the foreign key constraint is present on the chunk
   
         FOR chunk_id, chunk IN
           SELECT
             ch.id,
             format('%I.%I',ch.schema_name,ch.table_name)::regclass
           FROM _timescaledb_catalog.chunk ch
           WHERE
             ch.hypertable_id=ht_id
         LOOP
           RAISE NOTICE 'Checking chunk %', chunk;
           IF NOT EXISTS (
             SELECT FROM pg_constraint con
             WHERE
               con.contype='f' AND
               con.conrelid=chunk AND
               con.confrelid=con_frelid  AND
               pg_temp.constraint_columns(con.conrelid,con.conkey) = con_columns
           ) THEN
             RAISE WARNING 'Restoring constraint % on chunk %', con_name, chunk;
             PERFORM _timescaledb_functions.constraint_clone(con_oid, chunk);
             INSERT INTO _timescaledb_catalog.chunk_constraint(chunk_id, dimension_slice_id, constraint_name, hypertable_constraint_name) VALUES (chunk_id, NULL, con_name, con_name);
           END IF;
   
         END LOOP;
       END LOOP;
   
     END LOOP;
   
   END
   $$;
   
   DROP FUNCTION pg_temp.constraint_columns(regclass, int2[]);
   ```

   

   svenklemm committed Apr 13, 2024
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