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1dd06ede17
Backpatch to all supported versions, where applicable, to make backpatching of future fixes go more smoothly. Josh Soref Discussion: https://www.postgresql.org/message-id/CACZqfqCf+5qRztLPgmmosr-B0Ye4srWzzw_mo4c_8_B_mtjmJQ@mail.gmail.com
61 lines
2.6 KiB
PL/PgSQL
61 lines
2.6 KiB
PL/PgSQL
CREATE TABLE toasttest(descr text, cnt int DEFAULT 0, f1 text, f2 text);
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INSERT INTO toasttest(descr, f1, f2) VALUES('two-compressed', repeat('1234567890',1000), repeat('1234567890',1000));
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INSERT INTO toasttest(descr, f1, f2) VALUES('two-toasted', repeat('1234567890',30000), repeat('1234567890',50000));
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INSERT INTO toasttest(descr, f1, f2) VALUES('one-compressed,one-null', NULL, repeat('1234567890',1000));
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INSERT INTO toasttest(descr, f1, f2) VALUES('one-toasted,one-null', NULL, repeat('1234567890',50000));
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-- check whether indirect tuples works on the most basic level
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SELECT descr, substring(make_tuple_indirect(toasttest)::text, 1, 200) FROM toasttest;
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-- modification without changing varlenas
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UPDATE toasttest SET cnt = cnt +1 RETURNING substring(toasttest::text, 1, 200);
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-- modification without modifying assigned value
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UPDATE toasttest SET cnt = cnt +1, f1 = f1 RETURNING substring(toasttest::text, 1, 200);
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-- modification modifying, but effectively not changing
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UPDATE toasttest SET cnt = cnt +1, f1 = f1||'' RETURNING substring(toasttest::text, 1, 200);
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UPDATE toasttest SET cnt = cnt +1, f1 = '-'||f1||'-' RETURNING substring(toasttest::text, 1, 200);
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SELECT substring(toasttest::text, 1, 200) FROM toasttest;
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-- check we didn't screw with main/toast tuple visibility
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VACUUM FREEZE toasttest;
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SELECT substring(toasttest::text, 1, 200) FROM toasttest;
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-- now create a trigger that forces all Datums to be indirect ones
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CREATE FUNCTION update_using_indirect()
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RETURNS trigger
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LANGUAGE plpgsql AS $$
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BEGIN
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NEW := make_tuple_indirect(NEW);
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RETURN NEW;
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END$$;
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CREATE TRIGGER toasttest_update_indirect
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BEFORE INSERT OR UPDATE
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ON toasttest
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FOR EACH ROW
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EXECUTE PROCEDURE update_using_indirect();
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-- modification without changing varlenas
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UPDATE toasttest SET cnt = cnt +1 RETURNING substring(toasttest::text, 1, 200);
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-- modification without modifying assigned value
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UPDATE toasttest SET cnt = cnt +1, f1 = f1 RETURNING substring(toasttest::text, 1, 200);
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-- modification modifying, but effectively not changing
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UPDATE toasttest SET cnt = cnt +1, f1 = f1||'' RETURNING substring(toasttest::text, 1, 200);
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UPDATE toasttest SET cnt = cnt +1, f1 = '-'||f1||'-' RETURNING substring(toasttest::text, 1, 200);
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INSERT INTO toasttest(descr, f1, f2) VALUES('one-toasted,one-null, via indirect', repeat('1234567890',30000), NULL);
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SELECT substring(toasttest::text, 1, 200) FROM toasttest;
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-- check we didn't screw with main/toast tuple visibility
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VACUUM FREEZE toasttest;
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SELECT substring(toasttest::text, 1, 200) FROM toasttest;
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DROP TABLE toasttest;
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DROP FUNCTION update_using_indirect();
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