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Add a cardinality function for arrays.

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Unlike our other array functions, this considers the total number of
elements across all dimensions, and returns 0 rather than NULL when the
array has no elements.  But it seems that both of those behaviors are
almost universally disliked, so hopefully that's OK.

Marko Tiikkaja, reviewed by Dean Rasheed and Pavel Stehule
This commit is contained in:
Robert Haas
2014-01-21 12:38:53 -05:00
parent 033b2343fa
commit 01f7808b3e
8 changed files with 93 additions and 1 deletions
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8
src/test/regress/sql/arrays.sql
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@ -419,6 +419,14 @@ select array_length(array[[1,2,3], [4,5,6]], 1);
select array_length(array[[1,2,3], [4,5,6]], 2);
select array_length(array[[1,2,3], [4,5,6]], 3);
select cardinality(NULL::int[]);
select cardinality('{}'::int[]);
select cardinality(array[1,2,3]);
select cardinality('[2:4]={5,6,7}'::int[]);
select cardinality('{{1,2}}'::int[]);
select cardinality('{{1,2},{3,4},{5,6}}'::int[]);
select cardinality('{{{1}},{{2,3},{3,4}}}'::int[]);
select array_agg(unique1) from (select unique1 from tenk1 where unique1 < 15 order by unique1) ss;
select array_agg(ten) from (select ten from tenk1 where unique1 < 15 order by unique1) ss;
select array_agg(nullif(ten, 4)) from (select ten from tenk1 where unique1 < 15 order by unique1) ss;