67 lines
2.1 KiB
MySQL
67 lines
2.1 KiB
MySQL
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-- tests for tidscans
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CREATE TABLE tidscan(id integer);
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-- only insert a few rows, we don't want to spill onto a second table page
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INSERT INTO tidscan VALUES (1), (2), (3);
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-- show ctids
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SELECT ctid, * FROM tidscan;
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-- ctid equality - implemented as tidscan
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EXPLAIN (COSTS OFF)
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SELECT ctid, * FROM tidscan WHERE ctid = '(0,1)';
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SELECT ctid, * FROM tidscan WHERE ctid = '(0,1)';
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EXPLAIN (COSTS OFF)
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SELECT ctid, * FROM tidscan WHERE '(0,1)' = ctid;
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SELECT ctid, * FROM tidscan WHERE '(0,1)' = ctid;
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-- ctid = ScalarArrayOp - implemented as tidscan
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EXPLAIN (COSTS OFF)
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SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
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SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
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-- ctid != ScalarArrayOp - can't be implemented as tidscan
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EXPLAIN (COSTS OFF)
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SELECT ctid, * FROM tidscan WHERE ctid != ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
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SELECT ctid, * FROM tidscan WHERE ctid != ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
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-- tid equality extracted from sub-AND clauses
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EXPLAIN (COSTS OFF)
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SELECT ctid, * FROM tidscan
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WHERE (id = 3 AND ctid IN ('(0,2)', '(0,3)')) OR (ctid = '(0,1)' AND id = 1);
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SELECT ctid, * FROM tidscan
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WHERE (id = 3 AND ctid IN ('(0,2)', '(0,3)')) OR (ctid = '(0,1)' AND id = 1);
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-- exercise backward scan and rewind
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BEGIN;
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DECLARE c CURSOR FOR
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SELECT ctid, * FROM tidscan WHERE ctid = ANY(ARRAY['(0,1)', '(0,2)']::tid[]);
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FETCH ALL FROM c;
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FETCH BACKWARD 1 FROM c;
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FETCH FIRST FROM c;
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ROLLBACK;
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-- tidscan via CURRENT OF
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BEGIN;
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DECLARE c CURSOR FOR SELECT ctid, * FROM tidscan;
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FETCH NEXT FROM c; -- skip one row
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FETCH NEXT FROM c;
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-- perform update
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EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
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UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
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FETCH NEXT FROM c;
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-- perform update
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EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
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UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
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SELECT * FROM tidscan;
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-- position cursor past any rows
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FETCH NEXT FROM c;
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-- should error out
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EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
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UPDATE tidscan SET id = -id WHERE CURRENT OF c RETURNING *;
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ROLLBACK;
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DROP TABLE tidscan;
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