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Commit 01f7808

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robertmhaasrobertmhaas
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Add a cardinality function for arrays.
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
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‎doc/src/sgml/array.sgml

Copy file name to clipboardExpand all lines: doc/src/sgml/array.sgml
+13Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -337,6 +337,19 @@ SELECT array_length(schedule, 1) FROM sal_emp WHERE name = 'Carol';
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--------------
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2
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(1 row)
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</programlisting>
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<function>cardinality</function> returns the total number of elements in an
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array across all dimensions. It is effectively the number of rows a call to
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<function>unnest</function> would yield:
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<programlisting>
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SELECT cardinality(schedule) FROM sal_emp WHERE name = 'Carol';
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cardinality
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-------------
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4
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(1 row)
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</programlisting>
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</para>
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</sect2>

‎doc/src/sgml/func.sgml

Copy file name to clipboardExpand all lines: doc/src/sgml/func.sgml
+14Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11008,6 +11008,9 @@ SELECT NULLIF(value, '(none)') ...
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<indexterm>
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<primary>array_upper</primary>
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</indexterm>
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<indexterm>
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<primary>cardinality</primary>
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</indexterm>
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<indexterm>
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<primary>string_to_array</primary>
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</indexterm>
@@ -11164,6 +11167,17 @@ SELECT NULLIF(value, '(none)') ...
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<entry><literal>array_upper(ARRAY[1,8,3,7], 1)</literal></entry>
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<entry><literal>4</literal></entry>
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</row>
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<row>
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<entry>
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<literal>
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<function>cardinality</function>(<type>anyarray</type>)
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</literal>
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</entry>
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<entry><type>int</type></entry>
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<entry>returns the total number of elements in the array, or 0 if the array is empty</entry>
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<entry><literal>cardinality(ARRAY[[1,2],[3,4]])</literal></entry>
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<entry><literal>4</literal></entry>
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</row>
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<row>
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<entry>
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<literal>

‎src/backend/utils/adt/arrayfuncs.c

Copy file name to clipboardExpand all lines: src/backend/utils/adt/arrayfuncs.c
+12Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1739,6 +1739,18 @@ array_length(PG_FUNCTION_ARGS)
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PG_RETURN_INT32(result);
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}
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/*
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* array_cardinality:
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* returns the total number of elements in an array
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*/
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Datum
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array_cardinality(PG_FUNCTION_ARGS)
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{
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ArrayType *v = PG_GETARG_ARRAYTYPE_P(0);
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PG_RETURN_INT32(ArrayGetNItems(ARR_NDIM(v), ARR_DIMS(v)));
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}
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/*
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* array_ref :
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* This routine takes an array pointer and a subscript array and returns

‎src/include/catalog/catversion.h

Copy file name to clipboardExpand all lines: src/include/catalog/catversion.h
+1-1Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -53,6 +53,6 @@
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*/
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/* yyyymmddN */
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#define CATALOG_VERSION_NO 201312231
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#define CATALOG_VERSION_NO 201401211
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#endif

‎src/include/catalog/pg_proc.h

Copy file name to clipboardExpand all lines: src/include/catalog/pg_proc.h
+2Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -840,6 +840,8 @@ DATA(insert OID = 2092 ( array_upper PGNSP PGUID 12 1 0 0 0 f f f f t f i 2
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DESCR("array upper dimension");
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DATA(insert OID = 2176 ( array_length PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 23 "2277 23" _null_ _null_ _null_ _null_ array_length _null_ _null_ _null_ ));
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DESCR("array length");
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DATA(insert OID = 3179 ( cardinality PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 23 "2277" _null_ _null_ _null_ _null_ array_cardinality _null_ _null_ _null_ ));
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DESCR("array cardinality");
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DATA(insert OID = 378 ( array_append PGNSP PGUID 12 1 0 0 0 f f f f f f i 2 0 2277 "2277 2283" _null_ _null_ _null_ _null_ array_push _null_ _null_ _null_ ));
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DESCR("append element onto end of array");
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DATA(insert OID = 379 ( array_prepend PGNSP PGUID 12 1 0 0 0 f f f f f f i 2 0 2277 "2283 2277" _null_ _null_ _null_ _null_ array_push _null_ _null_ _null_ ));

‎src/include/utils/array.h

Copy file name to clipboardExpand all lines: src/include/utils/array.h
+1Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -204,6 +204,7 @@ extern Datum array_dims(PG_FUNCTION_ARGS);
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extern Datum array_lower(PG_FUNCTION_ARGS);
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extern Datum array_upper(PG_FUNCTION_ARGS);
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extern Datum array_length(PG_FUNCTION_ARGS);
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extern Datum array_cardinality(PG_FUNCTION_ARGS);
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extern Datum array_larger(PG_FUNCTION_ARGS);
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extern Datum array_smaller(PG_FUNCTION_ARGS);
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extern Datum generate_subscripts(PG_FUNCTION_ARGS);

‎src/test/regress/expected/arrays.out

Copy file name to clipboardExpand all lines: src/test/regress/expected/arrays.out
+42Lines changed: 42 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1455,6 +1455,48 @@ select array_length(array[[1,2,3], [4,5,6]], 3);
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(1 row)
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select cardinality(NULL::int[]);
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cardinality
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-------------
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(1 row)
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select cardinality('{}'::int[]);
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cardinality
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-------------
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0
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(1 row)
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select cardinality(array[1,2,3]);
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cardinality
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-------------
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3
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(1 row)
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select cardinality('[2:4]={5,6,7}'::int[]);
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cardinality
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-------------
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3
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(1 row)
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select cardinality('{{1,2}}'::int[]);
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cardinality
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-------------
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2
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(1 row)
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select cardinality('{{1,2},{3,4},{5,6}}'::int[]);
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cardinality
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-------------
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6
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(1 row)
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select cardinality('{{{1}},{{2,3},{3,4}}}'::int[]);
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cardinality
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-------------
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8
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(1 row)
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select array_agg(unique1) from (select unique1 from tenk1 where unique1 < 15 order by unique1) ss;
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array_agg
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--------------------------------------

‎src/test/regress/sql/arrays.sql

Copy file name to clipboardExpand all lines: src/test/regress/sql/arrays.sql
+8Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -419,6 +419,14 @@ select array_length(array[[1,2,3], [4,5,6]], 1);
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select array_length(array[[1,2,3], [4,5,6]], 2);
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select array_length(array[[1,2,3], [4,5,6]], 3);
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select cardinality(NULL::int[]);
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select cardinality('{}'::int[]);
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select cardinality(array[1,2,3]);
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select cardinality('[2:4]={5,6,7}'::int[]);
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select cardinality('{{1,2}}'::int[]);
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select cardinality('{{1,2},{3,4},{5,6}}'::int[]);
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select cardinality('{{{1}},{{2,3},{3,4}}}'::int[]);
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select array_agg(unique1) from (select unique1 from tenk1 where unique1 < 15 order by unique1) ss;
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select array_agg(ten) from (select ten from tenk1 where unique1 < 15 order by unique1) ss;
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select array_agg(nullif(ten, 4)) from (select ten from tenk1 where unique1 < 15 order by unique1) ss;

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