Hi,
Attached is a patch to add support for array_length(anyarray), which
only works for one-dimensional arrays, returns 0 for empty arrays and
complains if the array's lower bound isn't 1. In other words, does the
right thing when used with the arrays people use 99% of the time.
I'll add this to the next commit fest, but feel free to discuss it
before that.
Regards,
Marko Tiikkaja
*** a/doc/src/sgml/array.sgml
--- b/doc/src/sgml/array.sgml
***************
*** 338,343 **** SELECT array_length(schedule, 1) FROM sal_emp WHERE name =
'Carol';
--- 338,354 ----
2
(1 row)
</programlisting>
+
+ The single-argument overload of <function>array_length</function> can be used
+ to get the length of a one-dimensional array:
+ <programlisting>
+ SELECT array_length(schedule) FROM sal_emp WHERE name = 'Carol';
+
+ array_length
+ --------------
+ 2
+ (1 row)
+ </programlisting>
</para>
</sect2>
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 11096,11101 **** SELECT NULLIF(value, '(none)') ...
--- 11096,11112 ----
<row>
<entry>
<literal>
+ <function>array_length</function>(<type>anyarray</type>)
+ </literal>
+ </entry>
+ <entry><type>int</type></entry>
+ <entry>returns the length of the array (array must be
one-dimensional)</entry>
+ <entry><literal>array_length(array[1,2,3])</literal></entry>
+ <entry><literal>3</literal></entry>
+ </row>
+ <row>
+ <entry>
+ <literal>
<function>array_lower</function>(<type>anyarray</type>,
<type>int</type>)
</literal>
</entry>
*** a/src/backend/utils/adt/arrayfuncs.c
--- b/src/backend/utils/adt/arrayfuncs.c
***************
*** 1740,1745 **** array_length(PG_FUNCTION_ARGS)
--- 1740,1779 ----
}
/*
+ * array_length_single:
+ * Returns the length of a single-dimensional array. The array
must be
+ * single-dimensional or empty and its lower bound must be 1.
+ */
+ Datum
+ array_length_single(PG_FUNCTION_ARGS)
+ {
+ ArrayType *v = PG_GETARG_ARRAYTYPE_P(0);
+ int result;
+ int *lb;
+ int *dimv;
+
+ /* empty array */
+ if (ARR_NDIM(v) == 0)
+ PG_RETURN_INT32(0);
+
+ if (ARR_NDIM(v) != 1)
+ ereport(ERROR,
+ (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+ errmsg("input array is not
single-dimensional")));
+
+ lb = ARR_LBOUND(v);
+ if (lb[0] != 1)
+ ereport(ERROR,
+ (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+ errmsg("lower bound of array is not 1")));
+
+ dimv = ARR_DIMS(v);
+ result = dimv[0];
+ PG_RETURN_INT32(result);
+ }
+
+
+ /*
* array_ref :
* This routine takes an array pointer and a subscript array and returns
* the referenced item as a Datum. Note that for a pass-by-reference
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
***************
*** 840,845 **** DATA(insert OID = 2092 ( array_upper PGNSP PGUID 12 1 0 0
0 f f f f t f i 2
--- 840,847 ----
DESCR("array upper dimension");
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_ ));
DESCR("array length");
+ DATA(insert OID = 3179 ( array_length PGNSP PGUID 12 1 0 0 0 f f f
f t f i 1 0 23 "2277" _null_ _null_ _null_ _null_ array_length_single _null_
_null_ _null_ ));
+ DESCR("array length");
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_ ));
DESCR("append element onto end of array");
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_ ));
*** a/src/include/utils/array.h
--- b/src/include/utils/array.h
***************
*** 204,209 **** extern Datum array_dims(PG_FUNCTION_ARGS);
--- 204,210 ----
extern Datum array_lower(PG_FUNCTION_ARGS);
extern Datum array_upper(PG_FUNCTION_ARGS);
extern Datum array_length(PG_FUNCTION_ARGS);
+ extern Datum array_length_single(PG_FUNCTION_ARGS);
extern Datum array_larger(PG_FUNCTION_ARGS);
extern Datum array_smaller(PG_FUNCTION_ARGS);
extern Datum generate_subscripts(PG_FUNCTION_ARGS);
*** a/src/test/regress/expected/arrays.out
--- b/src/test/regress/expected/arrays.out
***************
*** 1455,1460 **** select array_length(array[[1,2,3], [4,5,6]], 3);
--- 1455,1482 ----
(1 row)
+ select array_length(NULL::int[]);
+ array_length
+ --------------
+
+ (1 row)
+
+ select array_length(array[1,2,3]);
+ array_length
+ --------------
+ 3
+ (1 row)
+
+ select array_length('{}'::int[]);
+ array_length
+ --------------
+ 0
+ (1 row)
+
+ select array_length('[2:4]={5,6,7}'::int[]);
+ ERROR: lower bound of array is not 1
+ select array_length('{{1,2}}'::int[]);
+ ERROR: input array is not single-dimensional
select array_agg(unique1) from (select unique1 from tenk1 where unique1 < 15
order by unique1) ss;
array_agg
--------------------------------------
*** a/src/test/regress/sql/arrays.sql
--- b/src/test/regress/sql/arrays.sql
***************
*** 419,424 **** select array_length(array[[1,2,3], [4,5,6]], 1);
--- 419,430 ----
select array_length(array[[1,2,3], [4,5,6]], 2);
select array_length(array[[1,2,3], [4,5,6]], 3);
+ select array_length(NULL::int[]);
+ select array_length(array[1,2,3]);
+ select array_length('{}'::int[]);
+ select array_length('[2:4]={5,6,7}'::int[]);
+ select array_length('{{1,2}}'::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;
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