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create or replace function read_table(relname regclass)
returns setof record
as $$
declare
pages int;
page int;
ctid tid;
r record;
sql_state text;
error text;
begin
select pg_relation_size(relname) / current_setting('block_size')::int into pages;
for page in 0 .. pages-1 loop
begin
for ctid in select t_ctid from heap_page_items(get_raw_page(relname::text, page)) loop
begin
execute format('SELECT * FROM %s WHERE ctid=%L', relname, ctid) into r;
if r is not null then
return next r;
end if;
exception -- bad tuple
when others then
get stacked diagnostics sql_state := RETURNED_SQLSTATE;
get stacked diagnostics error := MESSAGE_TEXT;
raise notice 'Skipping ctid %: %: %', ctid, sql_state, error;
end;
end loop;
exception -- bad page
when undefined_function then
raise exception undefined_function
using message = SQLERRM,
hint = 'Use CREATE EXTENSION pageinspect; to create it';
when others then
get stacked diagnostics sql_state := RETURNED_SQLSTATE;
get stacked diagnostics error := MESSAGE_TEXT;
raise notice 'Skipping page %: %: %', page, sql_state, error;
end;
end loop;
end;
$$ language plpgsql;
comment on function read_table(regclass) is
'read all good tuples from a table, skipping over all tuples that trigger an error';
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