pgsql批量修改sequences的start方式

DO $$DECLARE r record;
BEGIN
FOR r IN SELECT sequence_name FROM information_schema."sequences"
LOOP
 EXECUTE 'ALTER SEQUENCE '|| r.sequence_name ||' restart WITH 10000';
END LOOP;
END$$;

DO $$
DECLARE 
 r record;
 start_value integer := 0;
BEGIN
FOR r IN SELECT tablename||'_id_seq' AS sequence_name, tablename FROM pg_tables WHERE schemaname = 'public'
LOOP
 EXECUTE 'SELECT max(id)+1 AS max_value FROM ' || r.tablename INTO start_value;
 IF start_value IS NULL THEN start_value:= 1;
 END IF;
 RAISE NOTICE 'start_value % %', r.tablename,start_value;
 EXECUTE 'ALTER SEQUENCE '|| r.sequence_name ||' restart WITH ' || start_value;
END LOOP;
END$$;

# cat /etc/centos-release
CentOS Linux release 7.8.2003 (Core)
# su - postgres
Last login: Thu Oct 15 09:59:33 CST 2020 on pts/1

ppostgres@nodepg13-> psql -c "select version();"
             version             
---------------------------------------------------------------------------------------------------------
 PostgreSQL 13.0 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39), 64-bit
(1 row)

$ psql

postgres=# create sequence seq_1;
CREATE SEQUENCE
postgres=# select c.relname,c.relkind,s.* from pg_class c,pg_sequence s where c.oid=s.seqrelid;
 relname | relkind | seqrelid | seqtypid | seqstart | seqincrement |  seqmax  | seqmin | seqcache | seqcycle 
---------+---------+----------+----------+----------+--------------+---------------------+--------+----------+----------
 seq_1 | S  | 40968 |  20 |  1 |   1 | 9223372036854775807 |  1 |  1 | f
(1 row)

seqmax = 9223372036854775807

maxvalue
NO MAXVALUE
The optional clause MAXVALUE maxvalue determines the maximum value for the sequence. If this clause is not supplied or NO MAXVALUE is specified, then default values will be used. The default for an ascending sequence is the maximum value of the data type. The default for a descending sequence is -1.