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bb437f995d
This adds a new executor node named TID Range Scan. The query planner will generate paths for TID Range scans when quals are discovered on base relations which search for ranges on the table's ctid column. These ranges may be open at either end. For example, WHERE ctid >= '(10,0)'; will return all tuples on page 10 and over. To support this, two new optional callback functions have been added to table AM. scan_set_tidrange is used to set the scan range to just the given range of TIDs. scan_getnextslot_tidrange fetches the next tuple in the given range. For AMs were scanning ranges of TIDs would not make sense, these functions can be set to NULL in the TableAmRoutine. The query planner won't generate TID Range Scan Paths in that case. Author: Edmund Horner, David Rowley Reviewed-by: David Rowley, Tomas Vondra, Tom Lane, Andres Freund, Zhihong Yu Discussion: https://postgr.es/m/CAMyN-kB-nFTkF=VA_JPwFNo08S0d-Yk0F741S2B7LDmYAi8eyA@mail.gmail.com
101 lines
3.2 KiB
PL/PgSQL
101 lines
3.2 KiB
PL/PgSQL
-- tests for tidrangescans
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SET enable_seqscan TO off;
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CREATE TABLE tidrangescan(id integer, data text);
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-- empty table
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid < '(1, 0)';
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SELECT ctid FROM tidrangescan WHERE ctid < '(1, 0)';
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid > '(9, 0)';
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SELECT ctid FROM tidrangescan WHERE ctid > '(9, 0)';
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-- insert enough tuples to fill at least two pages
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INSERT INTO tidrangescan SELECT i,repeat('x', 100) FROM generate_series(1,200) AS s(i);
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-- remove all tuples after the 10th tuple on each page. Trying to ensure
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-- we get the same layout with all CPU architectures and smaller than standard
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-- page sizes.
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DELETE FROM tidrangescan
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WHERE substring(ctid::text FROM ',(\d+)\)')::integer > 10 OR substring(ctid::text FROM '\((\d+),')::integer > 2;
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VACUUM tidrangescan;
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-- range scans with upper bound
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid < '(1,0)';
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SELECT ctid FROM tidrangescan WHERE ctid < '(1,0)';
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid <= '(1,5)';
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SELECT ctid FROM tidrangescan WHERE ctid <= '(1,5)';
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid < '(0,0)';
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SELECT ctid FROM tidrangescan WHERE ctid < '(0,0)';
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-- range scans with lower bound
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid > '(2,8)';
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SELECT ctid FROM tidrangescan WHERE ctid > '(2,8)';
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE '(2,8)' < ctid;
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SELECT ctid FROM tidrangescan WHERE '(2,8)' < ctid;
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid >= '(2,8)';
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SELECT ctid FROM tidrangescan WHERE ctid >= '(2,8)';
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid >= '(100,0)';
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SELECT ctid FROM tidrangescan WHERE ctid >= '(100,0)';
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-- range scans with both bounds
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE ctid > '(1,4)' AND '(1,7)' >= ctid;
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SELECT ctid FROM tidrangescan WHERE ctid > '(1,4)' AND '(1,7)' >= ctid;
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EXPLAIN (COSTS OFF)
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SELECT ctid FROM tidrangescan WHERE '(1,7)' >= ctid AND ctid > '(1,4)';
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SELECT ctid FROM tidrangescan WHERE '(1,7)' >= ctid AND ctid > '(1,4)';
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-- extreme offsets
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SELECT ctid FROM tidrangescan WHERE ctid > '(0,65535)' AND ctid < '(1,0)' LIMIT 1;
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SELECT ctid FROM tidrangescan WHERE ctid < '(0,0)' LIMIT 1;
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SELECT ctid FROM tidrangescan WHERE ctid > '(4294967295,65535)';
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SELECT ctid FROM tidrangescan WHERE ctid < '(0,0)';
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-- NULLs in the range cannot return tuples
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SELECT ctid FROM tidrangescan WHERE ctid >= (SELECT NULL::tid);
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-- rescans
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EXPLAIN (COSTS OFF)
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SELECT t.ctid,t2.c FROM tidrangescan t,
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LATERAL (SELECT count(*) c FROM tidrangescan t2 WHERE t2.ctid <= t.ctid) t2
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WHERE t.ctid < '(1,0)';
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SELECT t.ctid,t2.c FROM tidrangescan t,
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LATERAL (SELECT count(*) c FROM tidrangescan t2 WHERE t2.ctid <= t.ctid) t2
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WHERE t.ctid < '(1,0)';
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-- cursors
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-- Ensure we get a TID Range scan without a Materialize node.
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EXPLAIN (COSTS OFF)
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DECLARE c SCROLL CURSOR FOR SELECT ctid FROM tidrangescan WHERE ctid < '(1,0)';
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BEGIN;
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DECLARE c SCROLL CURSOR FOR SELECT ctid FROM tidrangescan WHERE ctid < '(1,0)';
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FETCH NEXT c;
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FETCH NEXT c;
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FETCH PRIOR c;
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FETCH FIRST c;
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FETCH LAST c;
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COMMIT;
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DROP TABLE tidrangescan;
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RESET enable_seqscan;
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