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aeb9ae6457
As part of upper planner pathification (commit 3fc6e2d7f5) I redid
createplan.c's approach to the physical-tlist optimization, in which scan
nodes are allowed to return exactly the underlying table's columns so as
to save doing a projection step at runtime. The logic was intentionally
more aggressive than before about applying the optimization, which is
generally a good thing, but Andres Freund found a case in which it got
too aggressive. Namely, if any column is referenced more than once in
the parent plan node's sorting or grouping column list, we can't optimize
because then that column would need to have more than one ressortgroupref
label, and we only have space for one.
Add logic to detect this situation in use_physical_tlist(), and also add
some error checking in apply_pathtarget_labeling_to_tlist(), which this
example proves was being overly cavalier about whether what it was doing
made any sense.
The added test case exposes the problem only because we do not eliminate
duplicate grouping keys. That might be something to fix someday, but it
doesn't seem like appropriate post-beta work.
Report: <20160526021235.w4nq7k3gnheg7vit@alap3.anarazel.de>
76 lines
2.0 KiB
SQL
76 lines
2.0 KiB
SQL
--
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-- SELECT_DISTINCT
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--
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--
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-- awk '{print $3;}' onek.data | sort -n | uniq
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--
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SELECT DISTINCT two FROM tmp ORDER BY 1;
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--
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-- awk '{print $5;}' onek.data | sort -n | uniq
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--
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SELECT DISTINCT ten FROM tmp ORDER BY 1;
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--
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-- awk '{print $16;}' onek.data | sort -d | uniq
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--
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SELECT DISTINCT string4 FROM tmp ORDER BY 1;
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--
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-- awk '{print $3,$16,$5;}' onek.data | sort -d | uniq |
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-- sort +0n -1 +1d -2 +2n -3
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--
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SELECT DISTINCT two, string4, ten
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FROM tmp
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ORDER BY two using <, string4 using <, ten using <;
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--
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-- awk '{print $2;}' person.data |
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-- awk '{if(NF!=1){print $2;}else{print;}}' - emp.data |
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-- awk '{if(NF!=1){print $2;}else{print;}}' - student.data |
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-- awk 'BEGIN{FS=" ";}{if(NF!=1){print $5;}else{print;}}' - stud_emp.data |
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-- sort -n -r | uniq
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--
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SELECT DISTINCT p.age FROM person* p ORDER BY age using >;
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--
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-- Check mentioning same column more than once
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--
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EXPLAIN (VERBOSE, COSTS OFF)
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SELECT count(*) FROM
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(SELECT DISTINCT two, four, two FROM tenk1) ss;
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SELECT count(*) FROM
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(SELECT DISTINCT two, four, two FROM tenk1) ss;
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--
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-- Also, some tests of IS DISTINCT FROM, which doesn't quite deserve its
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-- very own regression file.
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--
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CREATE TEMP TABLE disttable (f1 integer);
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INSERT INTO DISTTABLE VALUES(1);
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INSERT INTO DISTTABLE VALUES(2);
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INSERT INTO DISTTABLE VALUES(3);
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INSERT INTO DISTTABLE VALUES(NULL);
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-- basic cases
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SELECT f1, f1 IS DISTINCT FROM 2 as "not 2" FROM disttable;
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SELECT f1, f1 IS DISTINCT FROM NULL as "not null" FROM disttable;
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SELECT f1, f1 IS DISTINCT FROM f1 as "false" FROM disttable;
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SELECT f1, f1 IS DISTINCT FROM f1+1 as "not null" FROM disttable;
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-- check that optimizer constant-folds it properly
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SELECT 1 IS DISTINCT FROM 2 as "yes";
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SELECT 2 IS DISTINCT FROM 2 as "no";
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SELECT 2 IS DISTINCT FROM null as "yes";
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SELECT null IS DISTINCT FROM null as "no";
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-- negated form
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SELECT 1 IS NOT DISTINCT FROM 2 as "no";
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SELECT 2 IS NOT DISTINCT FROM 2 as "yes";
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SELECT 2 IS NOT DISTINCT FROM null as "no";
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SELECT null IS NOT DISTINCT FROM null as "yes";
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